Fw: mkraid failure
Mihalis Tsoukalos
mtsouk at freemail.gr
Sat Mar 3 13:01:01 EET 2001
Με ένα
append="hdc=3737,255,63"
στο /etc/lilo.conf
το πρόβλημα λύθηκε και τώρα οι δύο ίδιοι δίσκοι έχουν και την ίδια
γεωμετρία.
Ευχαριστώ πολύ,
Μιχάλης.
Kyriakos Ginis <kyrginis at cyrix.home.ntua.gr> wrote in message
news:97oavd$2ri$1 at cyrix.home.ntua.gr...
On Fri, 2 Mar 2001 15:14:28 +0200, Mihalis Tsoukalos wrote:
>
>Το πρόβλημά μου ακόμα παραμένει ότι αν και οι δύο δίσκοι είναι ακριβώς οι
>ίδιοι, το fdisk δείχνει διαφορετικά νούμερα στην γεωμετρία τους και έτσι
δεν
>μπορώ να φτιάξω partition με το ίδιο μέγεθος:
>
>eugenia:/usr/share/doc/packages/raidtool # fdisk -l
>
>Disk /dev/hda: 255 heads, 63 sectors, 3737 cylinders
>Units = cylinders of 16065 * 512 bytes
>...
>
>Disk /dev/hdc: 16 heads, 63 sectors, 59560 cylinders
>Units = cylinders of 1008 * 512 bytes
>...
Από το Large-Disk-HOWTO:
14.2. Nonproblem: Identical disks have different geometry?
`I have two identical 10 GB IBM disks. However, fdisk gives different
sizes for them. Look:
# fdisk -l /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 -l /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
How come?'
What is happening here? Well, first of all these drives really are
10gig: hdb has size 255*63*1232*512 = 10133544960, and hdd has size
16*63*19650*512 = 10141286400, so, nothing is wrong and the kernel
sees both as 10.1 GB. Why the difference in size? That is because the
kernel gets data for the first two IDE disks from the BIOS, and the
BIOS has remapped hdb to have 255 heads (and 16*19650/255=1232
cylinders). The rounding down here costs almost 8 MB.
If you would like to remap hdd in the same way, give the kernel boot
parameters `hdd=1232,255,63'.
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