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Re: raid fun in debian (sarge)



hi ya mauricio


On Fri, 26 Mar 2004, Mauricio wrote:

> <Note:  I partitioned /dev/hd{c,d} using fdisk, but it seems that was 
> not needed>

you should move /dev/hdd  to /dev/hde  for reasons
mike and i were saying ... you cant boot or use the other
disk if one of um goes bonkers
	- its fairly common if the master disk is whacky,
	that the slave on the same cable will be ignored
	by the bios and its hardware drivers
 
> laurel:/home/debian# mdadm -Cv /dev/md0 -l1 -n2 /dev/hd{c,d}1
> mdadm: /dev/hdd1 appears to contain a reiserfs file system
>      size = 117210208K
> mdadm: size set to 117210112K
> Continue creating array? y
> mdadm: array /dev/md0 started.

good

> laurel:/home/debian#urel:/home/debian# mdadm --detail --scan
> ARRAY /dev/md0 level=raid1 num-devices=2 

good

...

> # fdisk /dev/md0
> [...]
> Disk /dev/md0: 120.0 GB, 120023154688 bytes
> 2 heads, 4 sectors/track, 29302528 cylinders
> Units = cylinders of 8 * 512 = 4096 bytes
> 
>      Device Boot      Start         End      Blocks   Id  System
> /dev/md0p1               1    29302528   117210110   83  Linux
> 
> Command (m for help): w
> The partition table has been altered!


bad boy ...  ???  or good ... if you really wanted to partition it

now you have to:
	mkreiserfs /dev/md0
	mount /dev/md0 /raid
	touch /raid/anything.txt

> laurel:/# mount -o rw /dev/md0 /mnt

you really should NOT have been able to mount it if
you did a fdisk and write .. and didnt format it

but ... its a nice feature to sometimes fix partition boundries 

> laurel:/# df -h
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/hda1              18G  3.5G   14G  21% /
> tmpfs                 252M     0  252M   0% /dev/shm
> /dev/md0              112G  177M  112G   1% /mnt
> laurel:/#
> 
> But, when I try to write something to /mnt, I am told it is a 
> read-only filesystem:
> 
> laurel:/# cd /mnt
> laurel:/mnt# touch m
> touch: cannot touch `m': Read-only file system
> laurel:/mnt#

its using the old superblock info from when the disk was
individually /dev/hdc  and /dev/hdd ..

c ya
alvin



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