Ellhniko Large Disk HOWTO
Andries Brouwer, aeb@cwi.nl
v2.2j, 25 Noembrioy 1999
Ola ta sxetika me th gewmetria toy diskoy kai to orio twn 1024 kylin
drwn. --- Gia opoiadhpote sxolia, dior8wseis, klp sxetika me thn ellh
nikh metafrash epikoinwnhste me ton Panagiwth Boydourh sth dieu8ynsh:
panos@veria1.freeserve.co.uk HOWTOs!large disk HOWTOs!disk, large
1. To problhma
Disks!Interface with BIOS BIOS!Interface with disks As poume oti exete
ena disko me 1024 kylindroys. As ypo8esoyme oti exete ki ena
leitoyrgiko poy xrhsimopoiei thn palia INT13 BIOS diasundesh me to I/O
toy diskoy. Tote exete problhma, afou ayth h diasundesh xrhsimopoiei
pedia me 10-bit gia toys kylindroys gia to I/O, opote kulindroi pera
twn 1024 den einai prosbasimoi.
Eytyxws, to Linux de xrhsimopoiei to BIOS, opote den yparxei problhma.
Dhladh, ektos apo dyo pragmata:
(1) Otan jekina to susthma, to Linux den trexei akoma opote den
mporeite na apofugete ta problhmata toy BIOS. Ayto exei merikes
epiptwseis sto LILO kai paromoioys fortwtes ekkinhshs.
(2) Einai aparaithto gia ola ta leitoyrgika poy xrhsimopoioun ena
disko na symfwnoun poy briskontai oi katatmhseis. Me alla logia, ean
xrhsimopoieite Linux kai, as poume, DOS se ena disko, tote prepei kai
ta dyo na metafrazoyn ton pinaka katatmhsewn me ton idio tropo. Ayto
exei merikes epiptwseis gia ton pyrhna toy Linux kai to fdisk.
Parakatw akoloy8ei mia leptomerhs perigrafh olwn twn sxetikwn 8ematwn.
Shmeiwste oti xrhsimopoihsa ton pyrhna 2.0.8 ws anafora. Alles
ekdoseis mporei na diaferoyn ligaki.
2. Perilhch
Exete enan kainourio megalo disko. Ti kanete; Apo thn pleyra toy
logismikou: xrhsimopoieite to fdisk (h, kalutera, cfdisk) gia na
dhmioyrghsete tis katatmhseis, kai meta to mke2fs gia na dhmioyrghsete
ena susthma arxeiwn, kai epeita mount gia na prosarthsete to kainourio
susthma sthn ierarxia.
De xreiazetai na diabasete ayto to HOWTO efoson den yparxoyn no
problhmata me megaloys diskoys aytes tis meres. H pleiochfia twn
problhmatwn dhmioyrgountai apo xrhstes poy nomizoyn oti mporei na
exoyn problhma kai egka8istoun ena diaxeiristh diskoy h xrhsimopoioun
to fdisk se expert mode, h dhlwnoyn th gewmetria toy diskoy sto LILO h
ston pyrhna.
Parola ayta, typika problhmata einai: (a) aparxaiwmenos ejoplismos,
(b) polla leitoyrgika ston idio disko kai, merikes fores, (g) h
ekkinhsh.
Symboylh:
Gia megaloys diskoys SCSI: to Linux toys yposthrizei apo polu nwris.
Den xreiazetai na kanete tipota.
Gia megaloys IDE diskoys (panw apo 8.4GB): breite mia nea sta8erh
ekdosh pyrhna (2.0.34 h newterh). Synh8ws ola 8a dior8w8oun, eidika an
de zhthsete apo to BIOS metafraseis LBA kai ta sxetika.
Gia polu megaloys IDE diskoys (panw apo 33.8 GB): deite to ``IDE
problhmata me 34+ GB diskoys'' parakatw.
Ean to LILO kremaei kata thn ekkinhsh, dhlwste kai sto linear arxeio
ry8misewn /etc/lilo.conf.
Mporei na yparjoyn problhmata me th gewmetria poy mporoun na ly8oun me
th dhlwsh ston pyrhna/LILO/fdisk.
Ean exete palio fdisk kai proeidopoiei gia ``epikalyptomenes''
katatmhseis: agnohste to, h elegjte xrhsimopoiwntas to cfdisk oti ola
einai pragmati entajei.
Ean nomizete oti kati paei la8os me to mege8os toy diskoy,
sigoyreyteite oti de mperdeuete tis dyadikes me tis dekadikes ``'',
kai ma8ete oti o eleu8eros xwros poy anaferei to df se enan adeio
disko einai ligo tois ekato mikrotero apo to mege8os ths katatmhshs
afou yparxoyn krathseis apo to susthma.
An akoma nomizete oti yparxei problhma, h apla eiste periergoi,
diabaste parakatw.
3. Monades kai Mege8h
units!megabyte units!gigabyte Ena kilobyte (kB) einai 1000 bytes. Ena
megabyte (MB) einai 1000 kB. Ena gigabyte (GB) einai 1000 MB. Ena
terabyte (TB) einai 1000 GB. Ayto einai to SI susthma. Parola ayta,
yparxei kosmos poy xrhsimopoiei to 1 MB=1024000 bytes kai mila gia
1.44 MB disketes kai kapoioi poy nomizoyn oti 1 MB=1048576 bytes. Edw
akoloy8w to proteinomeno standard kai grafw Ki, Mi, Gi, Ti gia tis
dyadikes monades, wste oi disketes einai 1440 KiB (1.47 MB, 1.41 MiB),
1 MiB einai 1048576 bytes (1.05 MB), 1 GiB einai 1073741824 bytes
(1.07 GB) kai 1 TiB einai 1099511627776 bytes (1.1 TB).
Swsta, oi kataskeyastes diskwn akoloy8oun to SI susthma kai
xrhsimopoioun dekadikes monades. Parola ayta, merika mynhmata toy
Linux kai merika fdisk programmata xrhsimopoioun ta sumbola MB kai GB
gia dyadika, h kai miktes dyadikes-dekadikes monades. Gia ayto, prin
nomisete oti o diskos sas einai mikroteros apo ayton poy sas
yposxe8hkan, ypologiste prwta to pragmatiko toy mege8os se dekadikes
monades (h apla bytes).
Sxetika me thn orologia kai tis syntomeuseis twn dyadikwn monadwn, o
Knuth exei mia enallaktikh protash, sygkekrimena na xrhsimopoioume
KKB, MMB, GGB, TTB, PPB, EEB, ZZB, YYB kai na ta kaloume megalo
kilobyte, megalo megabyte, ... megalo yottabyte. Grafei `Shmeiwste
oti to na grafoyme dyo fores to ka8e gramma yponoei kai dyadiko kai
megalo. Einai mia kalh protash, afou to `megalo gigabyte' akougetai
kalutero apo to `gibibyte'. Gia thn periptwsh mas to mono poy prepei
na prosejoyme einai oti ena megabyte exei akribws 1000000 bytes, kai
kapoios allos oros kai syntomeysh xreiazetai an ennooume kati allo.
3.1. Mege8os tomea
disk!sectorsize Sto paron keimeno ena tomeas exei 512 bytes. Ayto
einai sxedon panta alh8eia, ektos apo merikous MO poy xrhsimopoioun
2048 bytes, kai oles oi xwrhtikothtes poy dinontai parakatw prepei na
pollaplasiastoun epi tessera. (Otan xrhsimopoieite to fdisk se
tetoioys diskoys , sigoyreyteite oti exete ekdosh 2.9i kai anw , kai
dwste thn parametro `-b 2048'.)
3.2. Mege8os diskoy
disk!disksize Ena diskos me C kylindroys, H kefales kai S tomeis ana
ixnos exei C*H*S tomeis synolika kai xwrhtikothta C*H*S*512 bytes.
Gia paradeigma, an h etiketa leei C/H/S=4092/16/63 tote o diskos exei
4092*16*63=4124736 tomeis kai xwraei 4124736*512=2111864832 bytes
(2.11 GB). Kata sumbash, dinetai C/H/S=16383/16/63 gia diskoys
megaluteroys twn 8.4 GB, kai to mege8os to diskoy de mporei pia na
diabastei apo tis times C/H/S poy anaferontai apo to disko.
4. Prosbash diskoy
Gia na diabasete h na gracete kati apo to disko, prepei na deijoyme th
8esh sto disko, dinontas gia paradeigma ton tomea h thn enothta. An o
diskos einai SCSI, tote o ari8mos toy tomea phgainei katey8eian sthn
entolh SCSI kai o diskos thn katalabainei. An o diskos einai IDE
xrhsimopoiwntas LBA, isxuei to idio. Alla an o diskos einai palios RLL
h MFM h IDE ths pro-LBA epoxhs, tote o diskos perimenei ena triplo
ari8mo (kulindro, kefalh, tomea) gia na katadeijei to shmeio.
H antistoixia metaju grammikhs dieu8ynshs kai ths 3D shmeiografias
einai: gia ena disko me C kylindroys, H kefales kai S tomeis/ixnos h
8esh (c,h,s) se 3D h CHS einai h idia 8esh me c*H*S + h*S + (s-1) se
grammikh h LBA. (To meion ena einai epeidh oi tomeis arxizoyn kata
paradosh apo to 1, oxi to 0 opws sto 3D).
Kata synepeia, gia na prosbash se enan polu palioo mh-SCSI disko,
prepei na jeroyme thn gewmetria, dhladh, tis times C, H kai S.
4.1. Prosbash toy BIOS kai to orio twn 1024 kylindrwn
To Linux de xrhsimopoiei to BIOS, alla alla systhmata to
xrhsimopoioun. To BIOS, poy prouparxei toy LBA, prosferei tis roytines
diskoy INT13 poy dexontai (c,h,s) parametroys. (Akribestera: to AH
dialegei th leitoyrgia poy 8a ektelestei, to CH einai ta katw 8 bits
toy onomatos toy kylindroys, to CL exei sta bits 7-6 ta anw dyo bits
toy ari8mou toy kylindroy kai sta bits 5-0 ton ari8mo toy tomea, DH
einai o ari8mos ths kefalhs, kai DL einai o ari8mos toy diskoy (80h h
81h). Ayto ejhgei merika th diatajh toy pinaka katatmhsewn.)
Etsi, exoyme to CHS kwdikopoihmeno se 3 bytes, me 10 bits gia to onoma
toy kylindroy , 8 bits gia thn kefalh kai 6 bits gia ton ari8mo
ixnoys tomea (1-63). Ejypakouetai oti oi kulindroi mporei na einai apo
0 ews 1023 kai de mporoun na ari8mh8oun panw apo 1024 kulindroi apo to
BIOS.
To DOS kai ta Windows den allajan otan IDE diskoi me yposthrijh LBA
emfanisthkan, opote to DOS kai ta Windows synexisa na xreiazontai
gewmetria diskoy, akoma ki otan ayto de xreiazotan apo to I/O toy
diskoy, alla mono gia na epikoinwnoun me to BIOS. Ayto jana shmainei
oti to Linux xreiazetai th gewmetria opoy epikoinwnia me to BIOS h me
alla leitoyrgika apaiteitai, akoma kai se monternoys diskoys.
Ayth h katastash emfanisthke ta teleytaia tessera xronia peripoy, kai
emfanisthkan sthn agora diskoi poy de mporousan na klh8oun me tis
synarthseis INT13 (ka8oti ta 10+8+6=24 bits gia (c,h,s) den mporoun na
ari8mhsoyn panw apo 8.5 GB) kai mia nea diasundesh me to BIOS
sxediasthke: oi apokaloumenes Extended INT13 synarthseis, opoy to
DS:SI deixnei sto 16-byte Disk Address Packet poy perilambanei enan
8mpito ari8mo enothtwn.
Polu arga o kosmos ths Microsoft kineitai pros th xrhsh aytwn twn
Extended INT13 synarthsewn. Mallon se merika xronia apo shmera, kanena
monterno susthma de 8a xreiazetai th gewmetria toy diskoy.
4.2. Istoria toy BIOS kai twn oriwn toy IDE
ATA Specification (gia IDE diskoys) - to orio twn 137 GB
To polu 65536 kulindroi (ari8mhmenoi 0-65535), 16 kefales
(ari8mhmenes 0-15), 255 tomeis/ixnos (ari8mhmenoi 1-255) gia mia
megisth xwrhtikothta 267386880 tomewn (512 bytes o ka8enas),
dhladh, 136902082560 bytes (137 GB). Ayto akoma den einai
problhma (to 1999), alla 8a einai se merika xronia apo shmera.
BIOS Int 13 - to orio twn 8.5 GB
To polu 1024 kulindroi (0-1023), 256 kefales (0-255), 63
tomeis/ixnos (1-63) gia megisth xwrhtikothta 8455716864 bytes
(8.5 GB). Aytos einai enas arketa sobaros periorismos shmera.
Shmainei oti to DOS de mporei na xrhsimopoihsei toys neoys
megaloys diskoys.
To orio twn 528 MB
An oi idies times c,h,s xrhsimopoiountai gia to BIOS Int 13 call
kai gia to I/O toy IDE diskoy, kai oi dyo periorismoi
syndyazontai kai mporoume na xrhsimopoihsoyme to polu 1024
kylindroys, 16 kefales kai 63 tomeis/ixnos gia megisth telikh
xwrhtikothta 528482304 bytes (528MB), to perifhmo orio twn 504
MiB gia DOS me palio BIOS. Ayto egine problhma to 1993 kai
efeyre8hkan polla texnasmata, kai se yliko (LBA), kai firmware
(metafrazontas to BIOS) kai se software (diaxeiristes diskwn).
H ennoia ths 'metafrashs' efeyre8hke (1994): to BIOS mporouse na
xrhsimopoiei mia gewmetria otan epikoinwnouse me to disko kai
allh, ceydh, gewmetria otan milouse sto DOS, kai na metafrasei
metaju toys.
To orio twn 2.1 GB (Aprilios 1996)
Merika palia BIOS xrhsimopoioun mono 12 bits gia to pedio sth
CMOS RAM poy dinei ton ari8mo twn kylindrwn. Kata synepeia, o
ari8mos aytos mporei na einai to polu 4095, kai mono
4095*16*63*512=2113413120 bytes einai prosbasima. To na yparxei
megaluteros diskos exei ws apotelesma to kremasma kata thn
ekkinhsh. Ayto ekane diskoys me gewmetria 4092/16/63 arketa
dhmofilhs. Akoma kai shmera yparxoyn megaloi diskoi poy erxontai
me diakopth gia emfanizontai ws 4092/16/63. Deite kai to
over2gb.htm.
To orio twn 3.2 GB
Yphrxe ena megalo bug sto Phoenix 4.03 kai 4.04 BIOS poy ta
ekane na kollane sto CMOS setup gia diskoys megaluteroys twn
3227MB. Deite to over3gb.htm.
To orio twn 4.2 GB (Febroyarios 1997)
H aplh metafrash toy BIOS (ECHS=Extended CHS, merikes fores
legetai kai `Large disk support' h apla `Large') leitoyrgei me
ton synexh diplasiasmo toy ari8mou twn kefalwn kai ton
ypodiplasiasmo toy ari8mou twn kylindrwn poy deixnontai sto DOS,
mexri oi kulindroi na einai to polu 1024. To DOS kai ta Windows
95 de mporoun na diaxeiristoun 256 kefales, kai sthn periptwsh
poy o diskos anaferei 16 kefales, ayto shmainei oti o aplos
aytos mhxanismos mporei na doylecei gia mexri
8192*16*63*512=4227858432 bytes (me ceydh gewmetria me 1024
kylindroys, 128 kefales, 63 tomeis/ixnos). Shmeiwste oti to
ECHS den allazei ton ari8mo twn tomewn ana ixnos, opote an den
einai 63, to orio 8a einai akoma xamhlotero. Deite to
over4gb.htm.
To orio twn 7.9 GB
Ligo pio ejypna BIOS apofeugoyn ayto to problhma me th ru8mish
prwta toy ari8mou twn kefalwn se 15 (`revised ECHS'), wste h
ceydhs gewmetria na diathreitai me 240 kefales, arketo gia
1024*240*63*512=7927234560 bytes.
To orio twn 8.4 GB
Teleiwnontas, an to BIOS kanei o,ti mporei gia mia epityxh
metafrash, xrhsimopoiei 255 kefales me 63 tomeis/ixnos
(`assisted LBA' or just `LBA') kai ftanei ta
1024*255*63*512=8422686720 bytes, ligo mikrotero apo to
prohgoumeno orio twn 8.5 GB, efoson gewmetries me 256 kefales
prepei na apofeugontai. (H metafrash 8a xrhsimopoihsei gia ton
ari8mo kefalwn ton ari8mo H apo thn akoloy8ia 16, 32, 64, 128,
255 gia thn opoia h synolikh xwrhtikothta ftanei sta
1024*H*63*512, kai meta ypologizei ton ari8mo twn kylindrwn C ws
thn xwrhtikothta diairoumenh me (H*63*512).)
The 33.8 GB limit (August 1999)
To epomeno empodio erxetai me mege8h anw twn 33.8 GB. To
problhma einai oti me 16 kefales kai 63tomeis/ixnos ayto
antistoixei se ari8mo kylindrwn panw apo 65535, poy de xwraei se
short ari8mo. Ta perissotera BIOS shmera de mporoun na
xeiristoun tetoioys diskoys. (Deite Asus upgrades gia nees
ekdoseis poy doyleuoyn.) Pyrhnes palaioteroi twn 2.2.14 / 2.3.21
xreiazontai patch. Deite ``IDE problhmata me 34+ GB diskoys''
parakatw.
Gia peraiterw syzhthsh aytou toy 8ematos deite Breaking the Barriers
kai, gia perissoteres leptomereies, IDE Hard Drive Capacity Barriers.
Diskoi megaluteroi twn 8.4 GB anaferoyn th gewmetria toys ws
16383/16/63. Ayto shmainei oti h 'gewmetria' einai aneparkhs kai oti
h synolikh xwrhtikothta de mporei na ypologistei apo th gewmetria.
5. Ekkinhsh
booting!BIOS usage during disk!BIOS access during booting Otan to
susthma jekina, to BIOS diabazei ton tomea 0 (gnwstos kai ws MBR -
Master Boot Record) apo ton prwto disko (h apo disketa h CD-ROM) kai
diabazei ton kwdika poy briskei ekei - synh8ws enan fortwth. Ayta ta
programmatakia synh8ws den periexoyn odhgous kai xrhsimopoioun to
BIOS. Ayto shmainei oti o pyrhnas toy Linux mporei na fortw8ei mono
otan brisketai oloklhros stoys prwtoys 1024 kylindroys.
To problhma ayto lunetai polu eukola: sigoyreyteite oti o pyrhnas (kai
isws kai alla arxeia poy xreiazontai kata thn ekkinhsh, opws ta arxeia
toy LILO) briskontai se mia katatmhsh poy periexetai ej oloklhroy
stoys prwtoys 1024 kylindroys kai oti to BIOS mporei na exei prosbash
- ayto shmainei ton prwto h deutero disko.
Etsi: dhmioyrghste mia katatmhsh, as poume 10MB, wste na yparxei xwros
gia merikous pyrhnes, sigoyreuontas oti brisketai oloklhrh stoys
prwtoys 1024 kylindroys toy prwtoy h deuteroy diskoy. Prosarthste thn
sto /boot wste to LILO na balei o,ti xreiazetai ekei.
5.1. To LILO kai h epilogh `linear'
Allo ena shmeio sto opoio o fortwths kai to BIOS prepei na symfwnoun
einai h gewmetria toy diskoy. To LILO rwta ton pyrhna gia th
gewmetria, alla olo kai perissoteroi programmatistes odhgwn exoyn thn
kakh synh8eia na pairnoyn th gewmetria apo ton pinaka katatmhsewn,
anti na lene sto LILO ti 8a xrhsimopoiei to BIOS. Etsi, h gewmetria
apo ton pyrhna einai syxna axrhsth. Se aytes tis periptwseis einai
xrhsimo na balete sto LILO thn epilogh `linear'. To apotelesma einai
oti to LILO de xreiazetai th gewmetria kata thn egkatastash toy
fortwth alla kanei th metatroph ths grammikhs dieu8ynshs kata thn
ekkinhsh. Kai giati ayto den isxuei ej orismou; Yparxei ena
meionekthma: me thn epilogh `linear' to LILO den jerei gia ton ari8mo
twn kylindrwn, opote den mporei na sas proeidopoihsei an meros toy
pyrhna einai egkatesthmeno meta to peras twn 1024 kylindrwn kai mporei
na katalhjete me ena susthma poy den jekina.
5.2. Oi 1024 kulindroi den einai 1024 kulindroi
O Tim Williams grafei: `Eixa thn katatmhsh toy Linux stoys prwtoys
1024 kylindroys kai pali den jekinouse. Mono otan to ebala prin to 1
GB doulece'. Pws ginetai ayto; Aytos htan enas SCSI diskos me
AHA2940UW elegkth poy xrhsimopoiei eite H=64, S=32 (dhladh kulindroi
toy 1 MiB = 1.05 MB), h H=255, S=63 (dhladh kulindroi twn 8.2 MB),
analoga me tis epiloges ston disko kai to BIOS. Anamfisbhthta to BIOS
ypo8etei to prwto, opote oi 1024 kulindroi ftanoyn mexri to 1 GiB, enw
to Linux xrhsimopoiei to deutero kai to LILO nomize oti to orio htan
sta 8.4 GB.
6. Gewmetria diskoy, katatmhseis kai `epikaluceis'
disk!geometry disk!partitions Ean exete arketa leitoyrgika systhmata
stoys diskoys sas, tote ka8ena xrhsimopoiei mia h perissoteres
katatmhseis. Mia asymfwnia gia to poy briskontai aytes oi katatmhseis
8a exei katastrofika apotelesmata.
To MBR periexei enan pinaka katatmhsewn poy perigrafei poy briskontai
oi (prwtarxikes) katatmhseis. Yparxoyne 4 eggrafes gia 4 prwtarxikes
katatmhseis, me ka8e mia na einai
struct partition {
char active; /* 0x80: bootable, 0: not bootable */
char begin[3]; /* CHS for first sector */
char type;
char end[3]; /* CHS for last sector */
int start; /* 32 bit sector number (counting from 0) */
int length; /* 32 bit number of sectors */
};
(opoy CHS einai Cylinder/Head/Sector).
Aytes oi plhrofories einai perittes: h perioxh ths katatmhshs dinetai
kai apo to pedia twn 24-bit begin kai end, kai apo ta pedia twn
32-bit start kai length.
To Linux xrhsimopoiei mono ta pedia start kai length kai, etsi, mporei
na diaxeiristei katatmhseis me to polu 2^32 tomeis, dhladh,
katatmhseis to polu 2 TiB. Ayto einai 100 fores perissotero apo toys
shmerinous diskoys, opote mallon 8a einai arketo gia ta epomeno 8
peripoy xronia. (Etsi, oi katatmhseis mporei na einai polu megales,
alla yparxei o sobaros periorismos oti se ena ext2 susthma arxeiwn se
mhxanhma me 32-bit akeraioys ena arxeio de mporei na einai megalutero
apo 2 GiB.)
To DOS xrhsimopoiei ta begin kai end pedia, kai xrhsimopoiei thn BIOS
INT13 klhsh gia prosbash sto disko, kai etsi mporei na dei diskoys to
polu 8.4GB, akoma kai me BIOS poy kanei metafrash. (Oi katatmhseis de
mporoun na einai panw apo 2.1 GB logw periorismwn toy FAT16
systhmatos). To idio isxuei kai gia ta Windows 3.11 kai WfWG kai
Windows NT 3.* kai Novell NetWare.
Ta Windows 95 exoyn yposthrijh gia to Extended INT13, kai
xrhsimopoioun eidikous tupoys katatmhsewn (c, e, f anti gia b, 6, 5)
gia na deijoyn oti h katatmhsh 8a xrhsimopoih8ei etsi. Otan aytoi oi
tupoi katatmhsewn xrhsimopoiountai, ta pedia begin kai end periexoyn
ceutika stoixeia (1023/255/63). Ta Windows 95 OSR2 eishgagan to FAT32
susthma (tupoi katatmhsewn b or c), poy epitrepei katatmhseis to polu
2 TiB.
Ti einai ayta poy sas deixnei to fdisk gia `epikalyptomenes'
katatmhseis, otan sthn pragmatikothta ola einai entajei; Yparxei kati
'la8os': an deite ta begin kai end pedia tetoiwn katatmhsewn, opws
kanei to DOS, epikaluptontai. (Kai ayto de mporei na dior8w8ei, afou
ta pedia ayta de mporoun na apo8hkeusoyn ari8mous kylindrwn anw toy
1024 - 8a yparxei panta 'epikalych' otan exete perissoteroys apo 1024
kylindroys.). Parola ayta, an deite ta start kai length pedia, opws
kanei to Linux, kai ta Windows 95 sthn periptwsh katatmhsewn me tupo
c, e h f, tote ola einai entajei. Etsi, agnohste tis proeidopoihseis
toy otan to cfdisk einai ikanopoihmeno kai exete ena disko mono me
Linux. Prosejte otan o diskos moirazetai me to DOS. Xrhsimopoihste tis
entoles cfdisk -Ps /dev/hdx kai cfdisk -Pt /dev/hdx gia na deite ton
pinaka katatmhsewn toy /dev/hdx.
7. Metafrash kai Diaxeiristes Diskwn
disk!geometry translation BIOS!translating BIOS!LBA support H
gewmetria toy diskoy (me kefales, kylindroys kai ixnh) einai kati apo
thn epoxh toy MFM kai toy RLL. Ekeines tis meres ayth htan h
pragmatikothta. Shmera, me ta IDE h SCSI, kaneis den endiaferetai poia
einai h `pragmatikh' gewmetria toys diskoy. Akomh, o ari8mos twn
tomewn ana ixnos einai metablhtos: yparxoyn perissoteroi tomeis sto
ejwteriko toy diskoy kai etsi den yparxei `pragmatikos' ari8mos tomewn
ana ixnos. Anti8etws: h IDE entolh INITIALIZE DRIVE PARAMETERS (91h)
xrhsimopoieitai gia na leei ston disko poses kefales kai tomeis/ixnos
ypoti8etai oti exei. Einai arketa syxno na deite ena megalo monterno
disko me 2 kefales na anaferei 15 h 16 kefales sto BIOS, enw to BIOS
na anaferei 255 kefales sta programmata.
Gia ton xrhsth einai kalutero na exei to disko ws ena grammiko sunolo
tomewn ari8mhmenoys ws 0, 1, ..., kai na afhsei ta hlektronika na
broyn poy brisketai o ka8e tomeas ston disko. Ayth h grammikh ari8mhsh
legetai LBA.
Etsi h genikh eikona einai ws ejhs: To DOS, h kapoios allos fortwths,
mila sto BIOS, anaferontas ta (c,h,s). To BIOS ta metatrepei se LBA
xrhsimopoiwntas thn ceutikh gewmetria poy xrhsimopoiei o xrhsths. An o
diskos dextei to LBA tote ayth h timh xrhsimopoieitai gia thn
prosbash. Alliws, metatrepetai pisw se (c',h',s') xrhsimopoiwntas th
gewmetria poy anaferei o diskos kai etsi ginetai h prosbash.
Shmeiwste oti yparxei kapoia sugxysh sthn xrhsh toy `LBA': San oros
poy perigrafei tis dynatothtes toy diskoy shmainei `Grammikh
Diey8ynsiodothsh Temaxiwn = Linear Block Addressing' (se anti8esh me
th diey8ynsiodothsh CHS). San oros sto BIOS Setup, perigrafei ena
eidos metafrashs poy merikes fores kaleitai `boh8oumeno LBA = assisted
LBA' - deite parapanw to ```'''.
Kati paromoio symbainei otan o diskos den katalabainei to LBA alla to
BIOS jerei thn metafrash. (Sto setup ayto synh8ws onomazetai
`Large'.) Etsi to BIOS paroysiazei gewmetria (C,H,S) sto leitoyrgiko
susthma kai xrhsimopoiei (C',H',S') otan epikoinwnei me ton elegkth.
Synh8ws S = S', C = C'/N kai H = H'*N, opoye N einai h megaluterh
dunamh toy duo poy sigoyreuei oti C' <= 1024 (etsi h xwrhtikothta
stroggyleuetai pros ta katw se C' = C/N). Ayto epitrepei prosbash
mexri 8.4 GB (7.8 GiB).
(H trith epilogh sto setup einai synh8ws h `Normal', opoy de ginetai
kamia metafrash.)
Ean to BIOS den jerei ta `Large' h `LBA', tote yparxoyn luseis me
programmata. Diaxeiristes diskwn opws oi OnTrack h EZ-Drive
antika8istoun tis roytines diaxeirishs toy BIOS me tis dikes toys.
Ayto synh8ws epitygxanetai me to na yparxei o kwdikas toy diaxeiristh
sto MBR kai epakoloy8oys tomeis (to OnTrack onomazei ayton ton kwdika
DDO: Dynamic Drive Overlay), wste na ekkineitai prin to leitoyrgiko
susthma. Aytos einai o logos poy mporei na yparxoyn problhmata an
kapoios jekinhsei to mhxanhma me disketa kai yparxei kai diaxeirisths
diskoy.
To apotelesma einai ligo-polu to idio me th metafrash toy BIOS - alla
an yparxoyn diaforetika leitoyrgika systhmata ston idio disko tote
dhmioyrgountai polla problhmata.
To Linux yposthrizei to OnTrack apo thn ekdosh 1.3.14, kai to EZ-Drive
apo thn ekdosh 1.3.29. Perissoteres leptomereies dinontai parakatw.
8. Metafrash toy pyrhna gia diskoys IDE
disk!translation done by kernel Ean o pyrhnas anixneusei thn uparjh
kapoioy diaxeiristh diskoy se enan IDE disko, 8a prospa8hsei na
diairesei ton disko opws o diaxeirisths, wste to Linux na blepei tis
idies katatmhseis poy 8a eblepe, gia paradeigma, to DOS me to OnTrack
h to EZ-Drive. Parola ayta, DEN ginetai diairesh otan h gewmetria exei
dhlw8ei sth grammh entolwn - etsi h entolh `hd=cyls,heads,secs' mporei
na ejafanisei thn symbatothta me to diaxeiristh diskoy.
H anadiairesh ginetai xrhsimopoiwntas 4, 8, 16, 32, 64, 128, 255
kefales (kratwntas to H*C sta8ero) mexri eite C <= 1024 h H = 255.
Oi leptomereies akoloy8oun - oi ypoepikefalides einai ta mynhmata poy
emfanizontai kata thn ekkinhsh. Edw kai opoydhpote allou se ayto to
keimeno oi tupoi twn katatmhsewn dinontai se dekaejadika noumera.
8.1. EZD
disk!EZ-Drive translation disk!EZD translation To EZ-Drive anixneuetai
logw toy oti h prwth prwtarxikh katatmhsh exei tupo 55. H gewmetria
diabazetai opws perigrafetai parapanw anti toy pinaka katatmhsewn toy
tomea 0 - o pinakas diabazetai apo ton tomea 1. Oi ari8moi temaxiwn
toy diskoy den allazontai, alla eggrafes ston tomea 0
anadromologountai ston tomea 1. Ayth h symperifora mporei na allax8ei
anametalwttizontas ton pyrhna me #define FAKE_FDISK_FOR_EZDRIVE 0
sto ide.c.
8.2. DM6:DDO
disk!OnTrack DiskManager translation disk!DM6:DD0 translation O
OnTrack DiskManager (ston prwto disko) anixneuetai apo to gegonos oti
h prwth prwtarxikh katatmhsh exei tupo 54. H gewmetria diabazetai
opws anafer8hke parapanw kai oloklhros o diskos «metakineitai» kata 63
tomeis (wste o palios tomeas 63 na ginei o tomeas 0). Meta, ena
kainourio MBR (me ton pinaka katatmhsewn) diabazetai apo ton neo tomea
0. Fysika ayto ginetai gia na dhmioyrgh8ei xwros gia to DDO - gia ayto
den ginetai ayth h allagh stoys ypoloipoys diskoys.
8.3. DM6:AUX
disk!OnTrack DiskManager translation disk!DM6:AUX O OnTrack
DiskManager (stoys alloys diskoys) anixneuetai apo thn prwth
prwtarxikh katatmhsh poy exei tupo 51 h 53. H gewmetria diabazetai
opws perigrafetai parapanw.
8.4. DM6:MBR
disk!OnTrack DiskManager translation disk!DM6:MBR Mia palaioterh
ekdosh toy OnTrack DiskManager den anixneuetai apo ton tupo katatmhshs
alla apo to apotupwma toy. (Elegxetai an h metatopish poy brisketai
sta prwta 2 kai 3 bytes toy MBR den einai parapanw apo 430, an h
elleich einai ish me 0x55AA kai an akoloy8eitai apo mono byte). 3ana h
gewmetria diabazetai opws parapanw.
8.5. PTBL
disk!PTBL translation Telos, yparxei enas elegxos poy prospa8ei na
brei th metafrash apo tis times start kai end twn prwtarxikwn
katatmhsewn: Ean kapoia katatmhsh exei arxiko kai teliko tomea 1 kai
63 antistoixa kai exei telikes kefales 31, 63, 127 h 254, tote, efoson
synh8ws oi katatmhseis teleiwnoyn sta oria toy kylindroy, kai, epishs,
to IDE yposthrizei to polu 16 kefales, symperainetai oti to BIOS
metafrazei kai h gewmetria allazei gia na xrhsimopoih8oun 32, 64, 128
h 255 kefales antistoixa. Parola ayta, den ginetai kamia allagh otan h
paron gewmetria exei hdh 63 tomeis ana ixnos kai toylaxiston 63
kefales (to opoio oti exei hdh ginei mia allagh gewmetrias).
9. Synepeies
disk!consequences of translation Ti shmainoyn ola ayta; Gia toys
xrhstes toy Linux mono ena pragma: prepei na sigoyreytoun oti to LILO
kai to fdisk xrhsimopoioun th swsth gewmetria, opoy «swsth» gia to
fdisk einai h gewmetria poy xrhsimopoieitai kai apo ta alla
leitoyrgika ston idio disko, kai gia to LILO ayth poy 8a epitrecei th
swsth epikoinwnia me to BIOS kata thn ekkinhsh (synh8ws ayta ta dyo
sympiptoyn).
Pws jerei to fdisk gia th gewmetria; Rwta ton pyrhna, xrhsimopoiwntas
to HDIO_GETGEO ioctl, prin o xrhsths epembei sth gewmetria.
Pws jerei to LILO th gewmetria; Rwta thn pyrhna xrhsimopoiwntas to
HDIO_GETGEO ioctl. Alla o xrhsths mporei na epembei xrhsimopoiwntas
thn epilogh `disk=' sto /etc/lilo.conf (deite to lilo.conf(5)).
Mporeite na dwsete kai thn linear epilogh sto LILO, kai 8a apo8hkeusei
LBA diey8unseis anti gia CHS ston xarth toy, kai 8a brei th gewmetria
kata thn ekkinhsh (xrhsimopoiwntas thn INT 13 Function 8 gia na
rwthsei gia th gewmetria).
Pws jerei o pyrhnas ti na apanthsei; Prwta ap' ola, xrhsths mporei na
exei dhlwsei th gewmetria me thn entolh `hda=cyls,heads,secs' ston
pyrhna (deite bootparam(7)), isws xeirokinhta h zhtwntas ton boot
loader na dwsei ayth thn parametro ston pyrhna. Gia paradeigma
mporeite na peite sto LILO na dwsei mia tetoia parametro pros8etontas
to `append = "hda=cyls,heads,secs"' sto /etc/lilo.conf (deite
lilo.conf(5)). Diaforetika o pyrhnas 8a mantecei, pi8anon
xrhsimopoiwntas times poy brhke apo to BIOS h ton disko.
Einai dynaton (apo ton pyrhna 2.1.79) na allajete th gewmetria ston
pyrhna xrhsimopoiwntas to /proc. Gia paradeigma
# sfdisk -g /dev/hdc
/dev/hdc: 4441 cylinders, 255 heads, 63 sectors/track
# cd /proc/ide/ide1/hdc
# echo bios_cyl:17418 bios_head:128 bios_sect:32 > settings
# sfdisk -g /dev/hdc
/dev/hdc: 17418 cylinders, 128 heads, 32 sectors/track
#
9.1. Ypologizontas tis parametroys toy LILO
Merikes fores einai xrhsimo na orisete th gewmetria xrhsimopoiwntas to
`hda=cyls,heads,secs' sth grammh entolwn toy pyrhna. Synh8ws panta
xreiazetai secs=63, kai o logos poy to pros8etoyme einai gia na
oristoun oi heads. (Logikes times shmera einai heads=16 kai
heads=255.) Ti 8a prepei na orisoyme gia to cyls? Akribws ton ari8mo
poy 8a dwsei th swsth synolikh xwrhtikothta gia C*H*S tomeis. Gia
paradeigma, gia ena disko me 71346240 tomeis (36529274880 bytes) to C
ypologizetai ws 71346240/(255*63)=4441 (gia paradeigma xrhsimopoiwntas
ena programma san to bc), kai h parametros ekkinhshs einai
hdc=4441,255,63. Pws jeroyme thn swsth xwrhtikothta; Gia paradeigma,
# hdparm -g /dev/hdc | grep sectors
geometry = 4441/255/63, sectors = 71346240, start = 0
# hdparm -i /dev/hdc | grep LBAsects
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=71346240
dinei duo tropoys na broume ton synoliko ari8mo tomewn 71346240. O
pyrhnas mas dinei
# dmesg | grep hdc
...
hdc: Maxtor 93652U8, 34837MB w/2048kB Cache, CHS=70780/16/63
hdc: [PTBL] [4441/255/63] hdc1 hdc2 hdc3! hdc4 < hdc5 > ...
poy mas leei gia (toylaxiston) 34837*2048=71346176 kai gia (toylaxis
ton) 70780*16*63=71346240 tomeis. Se ayth thn periptwsh, h deuterh
timh symbainei na einai swsth, alla genika kai oi duo mporoun na
stroggylopoih8oun pros ta katw. Aytos einai enas kalos tropos na pros
eggisoyme to mege8os toy diskoy otan to hdparm den einai dia8esimo.
Pote mhn dinetai polu megalh timh gia to cyls! Sthn periptwsh twn SCSI
diskwn o akribhs ari8mos twn tomewn dinetai kata thn ekkinhsh:
SCSI device sda: hdwr sector= 512 bytes. Sectors= 17755792 [8669 MB] [8.7 GB]
(kai ta MB, GB einai stroggylopoihmena, oxi pros ta katw, kai
`dyadika').
10. Leptomereies
10.1. IDE - oi efta gewmetries
disk!IDE geometry setting O IDE odhgos exei pente phges plhroforiwn
gia th gewmetria. H prwth (G_user) einai ayth poy dhlwnetai apo ton
xrhsth sth grammh entolwn. H deuterh (G_bios) einai o pinakas
parametrwn diskwn toy BIOS (Fixed Disk Parameter Table) (gia ton prwto
kai deutero disko mono) poy diabazetai kata thn ekkinhsh toy
systhmatos, prin thn allagh se leitoyrgia 32-bit. H trith (G_phys)
kai tetarth (G_log) epistrefontai apo ton elegkth IDE ws apanthsh sthn
entolh IDENTIFY - einai h `fysikh' kai `trexoysa logikh' gewmetria
antistoixa.
Apo thn allh, o odhgos xreiazetai duo times gia th gewmetria: apo th
mia thn G_fdisk, poy epistrefetai apo to HDIO_GETGEO ioctl, kai apo
thn allh thn G_used, poy xrhsimopoieitai gia to pragmatiko I/O. Kai oi
duo xrhsimopoioun to G_user ean exei do8ei, to G_bios otan aytes oi
plhrofories einai dia8esimes sumfwna me to CMOS, h to G_phys an kanena
apo ta prohgoumena den einai dia8esimo. Ean to G_log fainetai logiko
tote to G_used ry8mizetai se ayto. Diaforetika, an to G_used den einai
swsto kai to G_phys fainetai logiko xrhsimopoieitai to G_phys gia na
ry8mistei to G_used. `Logiko' shmainei oti o ari8mos twn kefalwn
einai 1-16.
Me alla logia: h grammh entolwn yperbainei to BIOS, kai 8a ka8orisei
ti 8a dei to fdisk, alla an ka8orizei thn metafrazomenh gewmetria (me
parapanw apo 16 kefales), gia to I/O toy pyrhna 8a xrhsimopoih8oun oi
times ths entolhs IDENTIFY.
Shmeiwste oti to G_bios einai arketa anajiopisto: gia systhmata poy
jekinane me SCSI o prwtos kai deuteros diskos mporoun na einai SCSI
kai h gewmetria poy anaferei to BIOS gia sda mporei na xrhsimopoih8ei
apo ton pyrhna gia ta hda. Epishs, oi diskoi poy den anaferontai sto
setup toy BIOS den blepontai apo to BIOS. Ayto shmainei oti, p.x., se
ena susthma me IDE diskoys mono, an to hdb de do8ei sto BIOS setup, h
gewmetria poy anaferetai apo to BIOS gia ton prwto kai deutero disko
8a xrhsimopoih8ei gia ta hda kai hdc.
10.2. SCSI leptomereies
disk!SCSI geometry setting Sthn periptwsh toy SCSI ta pragmata einai
ligo diaforetika, afou oi SCSI entoles hdh xrhsimopoioun logikous
ari8mous, wste h `gewmetria' einai teleiws asxeth apo to I/O. Parola
ayta, o pinakas katatmhsewn einai idios, kai etsi to fdisk prepei na
brei th gewmetria, enw xrhsimopoiei kai to HDIO_GETGEO. Akomh, to
fdisk den diaxwrizei metaju twn IDE kai SCSI diskwn. Opws 8a deite
apo thn parakatw perigrafh, oi diaforoi odhgoi xrhsimopoioun o ka8enas
kapws diaforetikh gewmetria. Arketa mperdemenh katastash.
An den xrhsimopoieite to DOS, tote apofugete oles tis ru8mishs twn
metafrasewn, xrhsimopoieiste 64 kefales, 32 tomeis/ixnos (gia ena
boliko 1 MiB ana kulindro), an einai dynaton, wste na mhn exete
problhmata otan metaferete ton disko apo ton enan elegkth ston allo.
Merikoi SCSI odhgoi (aha152x, pas16, ppa, qlogicfas, qlogicisp) gia na
diathrhsoyn symbatothta me to DOS de 8a sas epitrecoyn na
xrhsimopoihsete panw apo 8 GiB akoma kai se susthma me mono Linux.
Ayto einai bug.
Poia einai h pragmatikh gewmetria; H eykoloterh apanthsh einai oti den
yparxei. Akoma ki an yphrxe, de 8elete na thn jerete kai sigoyra POTE
de 8a peite sto fdisk h to LILO h ton pyrhna poia einai. Einai ka8ara
metaju toy SCSI elegkth kai toy diskoy. Na to epanalabw: mono kapoios
anohtos leei sta fdisk/LILO/kernel thn pragmatikh gewmetria enos SCSI
diskoy.
Alla an eiste periergoi kai epimenete mporeite na rwthsete ton disko.
Yparxei h shmantikh entolh READ CAPACITY poy 8a dwsei to mege8os toy
diskoy kai yparxei kai h MODE SENSE entolh poy sth selida Rigid Disk
Drive Geometry (04) dinei ton ari8mo twn kefalwn kai twn kylindrwn
(ayta de mporoun na allajoyn) kai sth selida Format (03) dinei ton
ari8mo twn bytes ana tomea kai tomewn ana ixnos. To teleytaio noumero
den einai sta8ero, afou o ari8mos tomewn/ixnos ejartatai apo thn
perioxh toy diskoy: sto ejwteriko toy diskoy yparxoyn perissoteroi
tomeis/ixnos. To programma scsiinfo sto Linux 8a sas dwsei aytes tis
plhrofories. Yparxoyn polles leptomereies kai epiplokes kai einai
jeka8aro oti kaneis (oute kai to idio to leitoyrgiko) de 8elei na
jerei. Akomh, efoson mas endiaferei to fdisk kai to LILO, h synh8eis
apanthseis einai toy tupoy C/H/S=4476/27/171 - times poy de mporoun na
xrhsimopoih8oun apo to fdisk afou o pinakas katatmhsewn xrhsimopoiei
10/8/6 bits gia ta C/H/S.
Kai tote apo poy to HDIO_GETGEO briskei tis plhrofories; Apo ton
elegkth SCSI h kanontas mia ektimhsh. Merikoi odhgoi nomizoyn oti
8eloyme thn pragmatikh gewmetria alla, fysika, 8eloyme mono o,ti to
DOS h to fdisk toy OS/2 (h to AFDISK ths Adaptec, klp) xrhsimopoioun.
Shmeiwste oti to fdisk toy linux xreiazetai ton ari8mo kefalwn kai
tomewn/ixnos H kai S gia na metatrecei LBA noumera se c/h/s alla o
ari8mos twn kylindrwn C den xreiazetai. Merikoi odhgoi xrhsimopoioun
(C,H,S) = (1023,255,63) gia na deijoyn oti h xwrhtikothta toy diskoy
einai toylaxiston 1023*255*63 sectors. Ayto einai atyxes, afou den
mas dinei to pragmatiko mege8os kai 8a periorisei ta perissotera fdisk
se peripoy 8 GiB - enas arketa sobaros periorismos.
Sthn perigrafh parakatw, to M dhlwnei thn synolikh xwrhtikothta toy
diskoy kai C, H, S o ari8mos twn kylindrwn, kefalwn kai tomeis/ixnos.
Arkoun ta H, S an xrhsimopoihsoyme to C ws M / (H*S).
Kata sumbash, H=64, S=32.
aha1740, dtc, g_NCR5380, t128, wd7000:
H=64, S=32.
aha152x, pas16, ppa, qlogicfas, qlogicisp:
H=64, S=32 ektos ean C > 1024, opote H=255, S=63, C = min(1023,
M/(H*S)). (To C symptussetai kai to H*S*C den einai proseggish
toy M. Ayto 8a mperdecei tis perissoteres ekdoseis toy fdisk.)
To ppa.c xrhsimopoiei M+1 anti toy M kai leei oti ayto einai
logw enos bug sto sd.c, opoy to M einai ektos kata 1.
advansys:
H=64, S=32 ektos an C > 1024 kai akomh h epilogh `> 1 GB' toy
BIOS einai energopoihmenh, opote H=255, S=63.
aha1542:
Rwthste ton elegkth poia apo tis dyo metafraseis xrhsimopoiei
kai xrhsimopoihste eite H=255, S=63 h H=64, S=32. Sthn prwth
periptwsh 8a deite kata thn ekkinhsh "aha1542.c: Using extended
bios translation".
aic7xxx:
H=64, S=32 ektos an C > 1024, kai eite h epilogh "extended" kata
thn ekkinhsh dinetai h to `extended' bit xrhsimopoieitai sta
SEEPROM h BIOS, opote H=255, S=63. Sto Linux 2.0.36 ayth h
metafrash panta xrhsimopoieitai an de bre8ei SEEPROM, alla sto
Linux 2.2.6 an de bre8ei SEEPROM h metafrash xrhsimopoieitai an
o xrhsths to epi8ymei, xrhsimopoiwntas thn parametro ekkinhshs
(an bre8ei SEEPROM, h parametros agnoeitai). Ayto shmainei oti
to setup poy doyleuei sto 2.0.36 mporei na mhn ekkinhsei sto
2.2.6 (kai na apaitei thn epilogh `linear' sto LILO, h thn
parametro `aic7xxx=extended' ston pyrhna).
buslogic:
H=64, S=32 ektos ean C >= 1024, kai h extended metafrash
energopoih8hke ston elegkth, opote an M < 2^22 tote H=128, S=32;
alliws H=255, S=63. Omws, afou ginei ayth h epilogh gia
(C,H,S), o pinakas katatmhsewn diabazetai kai an gia tis treis
pi8anothtes (H,S) = (64,32), (128,32), (255,63) h timh
telikoH=H-1 bre8ei, ekeino to zeygari (H,S) xrhsimopoieitai, kai
to mhnyma "Adopting Geometry from Partition Table" typwnetai
kata thn ekkinhsh.
fdomain:
Breite th gewmetria stis parametroys diskwn toy BIOS, h diabaste
ton pinaka katatmhsewn kai xrhsimopoihste H=teleytaioH+1,
S=teleytaioS gia thn prwth katatmhsh, efoson einai adeia, h
xrhsimopoihste H=64, S=32 gia M < 2^21 (1 GiB), H=128, S=63 gia
M < 63*2^17 (3.9 GiB) kai H=255, S=63 diaforetika.
in2000:
Xrhsimopoihste to prwto apo ta (H,S) = (64,32), (64,63),
(128,63), (255,63) poy 8a dwsei C <= 1024. Sthn teleytaia
periptwsh, kofte to C se 1023.
seagate:
Diabaste ta C,H,S apo ton disko. Ean to C h S einai polu
megalo, tote balte S=17, H=2 kai diplasiaste to H mexri C <=
1024. Ayto shmainei oti to H 8a einai 0 an M > 128*1024*17 (1.1
GiB). Ayto einai bug.
ultrastor and u14_34f:
Ena apo ta tria (H,S) = (16,63), (64,32), (64,63)
xrhsimopoieitai, analogo me ton tropo leitoyrgias toy elegkth.
An o odhgos den dinei th gewmetria, manteuoyme xrhsimopoiwntas ton
pinaka katatmhsewn h xrhsimopoiwntas thn synolikh xwrhtikothta.
Koitajte ton pinaka katatmhsewn. Efoson, kata sumbash, oi katatmhseis
teleiwnoyn se orio kylindroys, mporoume, me dedomeno oti orio =
(telikoC,telikoH,telikoS) gia opoiadhpote katatmhsh, apla bazoyme H =
telikoH+1 kai S = telikoS. (8ymh8eite oti oi tomeis metriountai apo
to 1.) Me perissoteres leptomereies, ginontai ta parakatw. An den
yparxei eleu8erh katatmhsh, dialegoyme thn katatmhsh me to megalutero
arxikoC. Gia ayth thn katatmhsh, koitame to teliko+1, ypologismeno
pros8etontas ta arxh kai mhkos kai ypo8etontas oti h katatmhsh
teleiwnei se orio kylindroy. An kai oi dyo times symfwnoun h an
telikoC = 1023 kai arxh+mhkos einai akeraio pollaplasio toy
(telikoH+1)*telikoS, tote ypo8etoyme oti h katatmhsh einai ontws
ey8ygrammismenh me to orio toy kylindroy, kai bazoyme H = telikoH+1
kai S = telikoS. An ayto apotuxei, eite epeidh den yparxoyn
katatmhseis, eite epeidh exoyn perierges times, tote koitame pali mono
th xwrhtikothta toy diskoy M. Algori8mos: bazoyme H = M/(62*1024)
(stroggylopoihmeno kata panw), S = M/(1024*H) (stroggylopoihmeno
panw), C = M/(H*S) (stroggylopoihsh katw). Ayto exei to apotelesma na
exoyme ta (C,H,S) me to C to polu 1024 kai to S to polu 62.
11. To orio toy Linux IDE twn 8 GiB
O Linux IDE odhgos pairnei th gewmetria kai xwrhtikothta toy diskoy
(kai alla polla) xrhsimopoiwntas thn klhsh ATA IDENTIFY. Mexri
prosfata, o odhgos de 8a pisteye thn epistrefomenh timh ths lba
xwrhtikothtas (lba_capacity), an htan panw apo 10% apo thn
ypologizomenh me C*H*S. Parola ayta, oi kataskeyastes, se megaloys IDE
diskoys (me perissoteroys apo 16514064 tomeis) epistrefoyn ta C=16383,
H=16, S=63, gia ena sunolo 16514064 tomewn (7.8 GB), anejarthtws toy
pragmatikou toys mege8oys, alla dinoyn thn pragmatikh xwrhtikothta ws
lba.
Oi prosfatoi pyrhnes (2.0.34, 2.1.90) to jeroyn ayto kai to
dior8wnoyn. An exete palaiotero pyrhna kai de 8elete na
anaba8misteite, kai o pyrhnas blepei mono 8 GiB se enan polu
megalutero disko, dokimaste na allajete th roytina lba_capacity_is_ok
sto /usr/src/linux/drivers/block/ide.c se kati san
static int lba_capacity_is_ok (struct hd_driveid *id) {
id->cyls = id->lba_capacity / (id->heads * id->sectors);
return 1;
}
Gia mia pio prosektikh dior8wsh deite to 2.1.90.
11.1. BIOS epiplokes
Opws molis anefera, oi megaloi diskoi epistrefoyn C=16383, H=16, S=63
anejarthta apo to pragmatiko toys mege8os, enw to pragmatiko mege8os
epistrefetai ws LBAcapacity. Merika BIOS den to anagnwrizoyn ayto kai
metafrazoyn to 16383/16/63 se kati me ligoteroys kylindroys kai
perissoteres kefales, p.x. 1024/255/63 h 1027/255/63. Etsi, o pyrhnas
de mporei na anagnwrisei th gewmetria 16383/16/63, alla kai tis
mperdemenes ekdoseis ths toy BIOS. Apo ton pyrhna 2.2.2 ola ayta
dior8w8hkan (xrhsimopoiwntas ta H kai S toy BIOS kai ypologizontas to
C = xwrhtikothta/(H*S)). Synh8ws to problhma lunetai me to na
ry8mistei o diskos ws Normal sto BIOS (h akomh kalutero ws None, xwris
na anafer8ei ka8oloy sto BIOS). An ayto den einai dynato epeidh prepei
na ekkinhsete apo ayton h xrhsimopoieite DOS/Windows kai h anaba8mish
se 2.2.2 h megaluterh ekdosh de ginetai, xrhsimopoihste parametroys
ekkinhshs ston pyrhna.
11.2. Braxykyklwthres
Polloi IBM diskoi exoyn braxykyklwthres (jumpers) poy epitrepoyn na
epilejete metaju gewmetria 15 h 16 kefalwn. Oi synh8eis ry8miseis 8a
sas dwsoyn 16 kefales. Merikes fores kai oi dyo gewmetries dinoyn ton
idio ari8mo tomewn, merikes fores me 15 kefales dinontai ligoteroi
tomeis. Yparxei enas kalos logos gia ayth thn epilogh: o Petri
Kaukasoina grafei: `Enas 10.1 Gig IBM Deskstar 16 GP (IBM-DTTA-351010)
htan ry8mismenos gia 16 kefales alla sto palio PC (me AMI BIOS) den
ekkinouse kai eprepe na to ry8misw se 15 kefales. To hdparm -i leei
oti RawCHS=16383/15/63 kai LBAsects=19807200. Xrhsimopoiw 20960/15/63
gia na exw th megisth xwrhtikothta.' H gewmetria 16383/15/63 den
anagnwrizetai apo ton pyrhna, opote xreiazontai parametroi ekkinhshs.
Gia tis ry8miseis deite
http://www.storage.ibm.com/techsup/hddtech/hddtech.htm.
11.3. Braxykyklwthres poy meiwnoyn th synolikh xwrhtikothta
Polloi diskoi exoyn braxykyklwthres poy kanoyn ton disko na fainetai
mikroteros. Arketa anohto, kai mallon kanenas xrhsths toy Linux de 8a
8elei na to xrhsimopoihsei, alla merika BIOS kollane me megaloys
diskoys. H synh8hs lush einai na krathsete ton disko ejw apo to BIOS.
Alla ayto ginetai mono an den einai o diskos ekkinhshs.
To prwto sobaro orio htan twn 4096 kylindrwn (dhladh, 16 kefales kai
63tomeis/ixnos, 2.11GB). Gia paradeigma, enas Fujitsu MPB3032ATU 3.24
GB diskos exei gewmetria 6704/15/63, alla mporei na emfanistei ws
4092/16/63, kai meta anaferei LBA xwrhtikothta 4124736 tomeis, wste to
leitoyrgiko susthma na mporei na mantecei oti sthn pragmatikothta
einai megaluteros. Se ayth thn periptwsh (me ena BIOS poy kollaei otan
dei poso megalos einai o diskos sthn pragmatikothta wste na xreiazetai
o periorismos) xreiazontai parametroi ekkinhshs gia na peite sto Linux
to mege8os toy diskoy.
Oi perissoteroi diskoi mporoun na emfanistoun ws diskoi 2GB kai meta
na anaferoyn thn kommenh gewmetria ws 4092/16/63 h 4096/16/63, alla
akoma anaferoyn thn plhrh LBA xwrhtikothta. Tetoioi diskoi doyleuoyn
swsta kai anaferoyn thn plhrh xwrhtikothta sto Linux, asxeta me tis
8eseis twn braxykyklwthrwn.
Ena pio prosfato orio einai ``to orio twn 33.8 GB''. Pyrhnes
palaioteroi apo ton 2.3.21 xreiazontai patch gia na mporesoyn na
xrhsimopoihsoyn megaluteroys IDE diskoys apo 33.8GB. Merikoi
megaluteroi diskoi mporoun na ry8mistoun me braxykyklwthres wste na
emfanizontai ws 33.8 GB. Gia paradeigma, o IBM Deskstar 37.5 GB
(DPTA-353750) mporei na ry8mistei wste na emfanizetai ws 33.8 GB, kai
meta anaferei gewmetria 16383/16/63 opws oloi oi megaloi diskoi, alla
LBA xwrhtikothta 66055248 (antistoixa me 65531/16/63 h 4111/255/63)).
Aytoi, otan ry8mistoun ws 33.8GB, xreiazontai parametroys gia plhrh
xwrhtikothta sto Linux. Deite to the BIOS 33.8 GB limit.
12. To orio twn 65535 kylindrwn sto linux
To HDIO_GETGEO ioctl epistrefei ton ari8mo twn kylindrwn se tupo
short. Ayto shmainei oti an exte panw apo 65535 kylindroys, o ari8mos
perikoptetai kai (gia ena typiko SCSI disko me 1 MiB ana kulindro)
enas diskos 80 GiB 8a fainetai ws 16 GiB. Efoson anagnwris8ei ayto to
problhma, apofeugetai eukola.
12.1. IDE problhmata me diskoys 34+ GB
Diskoi megaluteroi twn 33.8 GB de doyleuoyn me pyrhnes palaioteroys
toy 2.3.21. Oi leptomereies einai: Ypo8este oti agorasate ena neo
IBM-DPTA-373420 disko me xwrhtikothta 66835440 tomeis (34.2 GB).
Pyrhnes palaioteroi toy 2.3.21 8a sas poune oti to mege8os toy diskoy
einai 769*16*63 = 775152 tomeis (0.4 GB), poy einai ligo
apogohteytiko. Kai dinontas tis parametroys hdc=4160,255,63 de boh8aei
ka8oloy - apla agnoountai. Ti symbainei; H roytina idedisk_setup()
briskei th gewmetria poy anaferei o diskos (poy einai 16383/16/63) kai
parakamptei o,ti dinei o xrhsths sth grammh entolwn, wste ta dedomena
toy xrhsth na xrhsimopoiountai mono gia th gewmetria toy BIOS. H
roytina current_capacity() h idedisk_capacity() ypologizei ton ari8mo
kylindrwn ws 66835440/(16*63)=66305, alla afou apo8hkeuetai se short
ari8mo, ginetai 769. Efoson h lba_capacity_is_ok() katestrece to
id->cyls, ka8e epomenh klhsh se ayto 8a einai la8os kai o diskos 8a
ginei 769*16*63. Gia pollous pyrhnes yparxei patch. Gia ton 2.0.38
mporei na bre8ei sto ftp.kernel.org. Gia ton 2.2.12 einai sto
www.uwsg.indiana.edu. Oi 2.2.14pre pyrhnes yposthrizoyn aytous toys
diskoys. Stoys 2.3.* pyrhnes, yparxei yposthrijh apo ton 2.3.21.
Pantws, to problhma mporei na `ly8ei' ``xrhsimopoiwntas toys
braxykyklwthres'' gia na kopei to mege8os se 33.8 GB. Se polles
periptwseis mia ``anaba8mish toy BIOS'' 8a xreiastei an 8elete na
ekkinhsete to susthma apo ayto to disko.
13. Ektetamenes kai logikes katatmhseis
``Parapanw,'' eidame oti th domh toy MBR (tomeas 0): kwdikas toy
fortwth akoloy8oumenos apo 4 eggrafes katatmhsewn 16 byte h ka8e mia,
akoloy8oumeno apo to AA55 apotupwma. Katatmhseis tupoy 5 h F h 85
(dekaejadiko) exoyn eidikh shmasia: perigrafoyn ektetamenes
katatmhseis: kommatia toy diskoy poy 8a katatmh8oun se logikes
katatmhseis. (Etsi, mia ektetamenh katatmhsh einai apla ena doxeio,
de mporei na xrhsimopoih8ei apo monh ths, alla mesw twn logikwn
katatmhsewn poy periexei.) Mono h topo8esia toy prwtoy tomea mias
ektetamenhs katatmhshs einai shmantikh. Aytos o prwtos tomeas periexei
enan pinaka katatmhsewn me 4 eggrafes: mia logikh, mia ektetamenh kai
dyo axrhsimopoihtes. Me ayton ton tropo mporei na dhmioyrgh8ei mia
alysida pinakwn skorpismenh pantou ston disko, opoy o prwtos pinakas
perigrafei treis prwtarxikes katatmhseis kai mia ektetamenh, kai ka8e
epomenos pinakas perigrafei mia logikh katatmhsh kai ton tomea toy
epomenoy pinaka.
Einai shmantiko na to katalabete ayto: Otan kapoios xrhsths kanei
kapoia blakeia xwrizontas ton disko toy, 8elei na jerei: Einai ta
dedomena moy akoma ekei; H apanthsh einai synh8ws nai. Alla an
dhmioyrgh8hkan logikes katatmhseis, tote oi pinakes poy perigrafoyn
tis katatmhseis aytes grafthkan sthn arxh twn katatmhsewn aytwn kai ta
dedomena poy yphrxan ekei xa8hkan.
To sfdisk 8a deijei olh thn alysida. p.x.,
# sfdisk -l -x /dev/hda
Disk /dev/hda: 16 heads, 63 sectors, 33483 cylinders
Units = cylinders of 516096 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/hda1 0+ 101 102- 51376+ 83 Linux
/dev/hda2 102 2133 2032 1024128 83 Linux
/dev/hda3 2134 33482 31349 15799896 5 Extended
/dev/hda4 0 - 0 0 0 Empty
/dev/hda5 2134+ 6197 4064- 2048224+ 83 Linux
- 6198 10261 4064 2048256 5 Extended
- 2134 2133 0 0 0 Empty
- 2134 2133 0 0 0 Empty
/dev/hda6 6198+ 10261 4064- 2048224+ 83 Linux
- 10262 16357 6096 3072384 5 Extended
- 6198 6197 0 0 0 Empty
- 6198 6197 0 0 0 Empty
...
/dev/hda10 30581+ 33482 2902- 1462576+ 83 Linux
- 30581 30580 0 0 0 Empty
- 30581 30580 0 0 0 Empty
- 30581 30580 0 0 0 Empty
#
Einai dynaton na dhmioyrgh8oun xalasmenoi pinakes. Polloi pyrhnes
mpainoyn se kuklo an kapoia ektetamenh katatmhsh deixnei pisw ston
eayto ths h se prohgoumenh katatmhsh sthn alysida. Einai dynaton na
yparxoyn duo ektetamenes katatmhseis se kapoion pinaka wste h alysida
na xwrizei. (Gia paradeigma, ayto mporei na symbei an ena fdisk den
anagnwrizei ta 5, F, 85 ws ektetamenoys tupoys kai dhmioyrghsei ena 5
dipla se ena F.) Kanena koino fdisk de mporei na xeiristei tetoies
katastaseis, opote xreiazetai ligh doyleia me to xeri gia na
dior8w8oun. O pyrhnas toy Linux 8a dextei mia xwrismenh alysida se
ejwteriko epipedo. Dhladh, mporeite na exete dyo alysides gia logikes
katatmhseis. Merikes fores ayto einai xrhsimo, afou mporeite na exete
tupo 5 gia to DOS kai tupo 85, aorato sto DOS, gia to Linux, wste to
fdisk toy DOS na mhn kollhsei epeidh oi katatmhseis sas einai peran
twn 1024 kylindrwn.
14. Lunontas problhmata
Polloi nomizoyn oti exoyn problhma, enw sthn pragmatikothta den
yparxei kanena. H pisteuoyn oti ta problhmata poy exoyn ofeilontai sth
gewmetria toy diskoy, enw ayto den exei na kanei tipota me to problhma
toys. Ta parapanw mporei na akougontai periploka alla h gewmetria
einai kati sxetika aplo: afhste thn opws einai kai ola 8a einai mia
xara· h to polu na dwsete thn parametro `linear' sto LILO an den
proxwraei meta to `LI' otan jekina. Prosejte ta mynhmata toy pyrhna
kai 8ymh8eite: oso perissotero peirazete thn gewmetria (orizontas
kefales kai kylindroys sto LILO, to fdisk kai ton pyrhna) toso
pi8anotero einai na mh doylecei. Xontrika ola einai entajei apo mona
toys.
Kai 8ymh8eite: poy8ena sto Linux de xrhsimopoieite h gewmetria, opote
kanena problhma de mporei na dhmioyrgh8ei apo aythn. H gewmetria
xrhsimopoieite mono apo to LILO kai to fdisk. Etsi, an to LILO den
jekina ton pyrhna, mporei na einai problhma gewmetrias. An diaforetika
leitoyrgika den katalabainoyn ton pinaka katatmhsewn, mporei na einai
problhma gewmetrias. Tipota perissotero. Sygkekrimena, an to mount de
doyleuei mhn anhsyxeite gia th gewmetria· to problhma einai allou.
14.1. Problhma: to Linux xrhsimopoiei la8os gewmetria gia ton disko
moy.
Einai pi8ano enas diskos na labei la8os gewmetria. O pyrhnas rwta to
BIOS gia ta hd0 kai hd1 (toys diskoys 80H kai 81H sumfwna me to BIOS)
kai ypo8etei oti einai gia ta hda kai hdb. Alla an ekkineite apo SCSI,
oi prwtoi dyo diskoi mporei na einai SCSI kai o pemptos diskos, poy
einai prwtos IDE hda diskos, pairnei th gewmetria toy sda. Ayto
lunetai eukola me thn parametro ekkinhshs `hda=C,H,S' me tis
katallhles times C, H kai S, eite kata thn ekkinhsh h sto
/etc/lilo.conf.
14.2. Problhma: Idioi diskoi exoyn diaforetikh gewmetria
`Exw dyo omoioys diskoys 10GB IBM. To fdisk dinei diaforetiko mege8os
ston ka8ena. Deite:
# fdisk /dev/hdb
Disk /dev/hdb: 255 heads, 63 sectors, 1232 cylinders
Units = cylinders of 16065 * 512 bytes
Device Boot Start End Blocks Id System
/dev/hdb1 1 1232 9896008+ 83 Linux native
# fdisk /dev/hdd
Disk /dev/hdd: 16 heads, 63 sectors, 19650 cylinders
Units = cylinders of 1008 * 512 bytes
Device Boot Start End Blocks Id System
/dev/hdd1 1 19650 9903568+ 83 Linux native
Pws kai;'
Ti symbainei edw; Prwta apo ola, oi diskoi einai pragmati 10GB: to hdb
exei mege8os 255*63*1232*512 = 10133544960, kai to hdd 16*63*19650*512
= 10141286400, etsi tipota de symbainei kai o pyrhnas toys blepei kai
toys duo san 10.1 GB. Giati h diafora sto mege8os; Ayto symbainei
epeidh o pyrhnas pairnei tis plhrofories gia toys prwtoys dyo IDE
diskoys apo to BIOS, kai to BIOS exei balei ston hdb 255 kefales (kai
16*19650/255=1232 cylinders). H stroggylopoihsh kostizei sxedon 8MB.
An 8elete mporeite na allajete ton hdd me ton idio tropo kai na dwsete
ston pyrhna kata thn ekkinhsh `hdd=1232,255,63'.
14.3. Problhma: to fdisk blepei perissotero xwro apo to df
To fdisk 8a sas pei posa temaxia (blocks) yparxoyn ston disko. An
dhmioyrghsete susthma arxeiwn, p.x. me to mke2fs, tote to susthma
krata ligo xwro gia logoys diaxeirishs· peripoy 4% toy synolikou
xwroy, perissotero an 8elete polla inodes. Gia paradeigma:
# sfdisk -s /dev/hda9
4095976
# mke2fs -i 1024 /dev/hda9
mke2fs 1.12, 9-Jul-98 for EXT2 FS 0.5b, 95/08/09
...
204798 blocks (5.00%) reserved for the super user
...
# mount /dev/hda9 /somewhere
# df /somewhere
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/hda9 3574475 13 3369664 0% /mnt
# df -i /somewhere
Filesystem Inodes IUsed IFree %IUsed Mounted on
/dev/hda9 4096000 11 4095989 0% /mnt
#
Exoyme mia katatmhsh 4095976 blocks, kanoyme ena ext2 susthma, to
prosartoume kai telika exoyme mono 3574475 blocks· 521501 blocks (12%)
xa8hkan sta inodes kai th diaxeirish. Shmeiwste oti h diafora metaju
twn 3574475 kai twn 3369664 blocks einai ta 13 poy xrhsimopoiountai
kai ta 204798 poy krath8hkan gia ton yperxrhsth. To teleytaio noumero
mporei na allajei me to tune2fs. To `-i 1024' einai logiko na xrhsi
mopoih8ei mono gia katatmhseis newn h taxydromeioy, opoy yparxoyn
polla kai mikra arxeia. To synh8ismeno 8a htan:
# mke2fs /dev/hda9
# mount /dev/hda9 /somewhere
# df /somewhere
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/hda9 3958475 13 3753664 0% /mnt
# df -i /somewhere
Filesystem Inodes IUsed IFree %IUsed Mounted on
/dev/hda9 1024000 11 1023989 0% /mnt
#
Twra mono 137501 blocks (3.3%) xrhsimopoiountai gia inodes, wste
exoyme 384 MB perissotera apo prin. (Profanws ka8e inode xrhsimopoiei
128 bytes). Apo thn allh, mporoume na exoyme to polu 1024000 arxeia
(parapanw apo arketa), anti twn 4096000 (yperbolika polla) poy eixame
prin.