8.04 md raid5 troubleshooting

[Marius Gedminas]

On Wed, Nov 09, 2011 at 12:24:51PM +0100, Reinhard Haller wrote:
> md0 : active raid5 sda3[3](F) sdb2[1] sdc2[2]
> 775119872 blocks level 5, 256k chunk, algorithm 2 [3/2] [_UU]
...
> fdisk says about /dev/sda:
> 
> Platte /dev/sda: 400.1 GByte, 400088457216 Byte
...
>    Gerät  boot.     Anfang        Ende     Blöcke   Id  System
> /dev/sda1   *           1          25      200781   83  Linux
> /dev/sda2              26         392     2947927+  82  Linux Swap / Solaris
> /dev/sda3             393       48641   387560092+  fd  Linux raid autodetect
...
> 
> The only shortly available spare device is a 1TB SATA drive.
> 
> smartctl on /dev/sda reports a healthy drive and /dev/sda1 is still available

Did you run a self-test?  smartctl -t long /dev/sda and then (a couple
of hours later, it'll tell you the estimated test time) check the
results with I forget which exactly option, but smartctl -a /dev/sda
works.

> What is the suggested way to get the array back working?

Connect the spare drive, partition it, use mdadm to hot-add it, wait
while it syncs in the background.

> Does it make sense to "revert" the faulty state of /dev/sda?

I doubt it -- if the disk failed once, it'll likely fail again.

> How to partition the 1 TB drive to be able to grow the array after
> replacing all old drives with 1TB ones?

I think you'd have to replace all the current partitions that comprise
your RAID array with larger ones, one by one (waiting for full syncs),
and then use mdadm --grow to enlarge the array (and wait for a sync),
and then use resize2fs (assuming ext3 fs) to enlarge the partition.

Up-to-date backups are recommended, as per usual.

Marius Gedminas
-- 
Any sufficiently advanced Operating System is indistinguishable from Linux.
                -- Jim Dennis
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 190 bytes
Desc: Digital signature
URL: <https://lists.ubuntu.com/archives/ubuntu-users/attachments/20111109/2f8c383b/attachment.sig>