Re: raid5+ lvm2 disaster

Hmm. I posted the following (from my subbed addr) but it never appeared
- in my inbox or on MARC.
Perhaps I hit a keyword; reposting with some tweaks.

On Fri, 09 Jul 2004 16:18:07 -0700, "Matthew (RAID)"
[off-list ref] said:

One more thing - run hdparm to check that the DMA settings are
consistent - the same on all drives.
Switch to the most conservative settings (the slowest ones).
If they're not the same on all drives, I've heard (on /.) that it can
cause some of the problems you're seeing.

My original reply below - it just went to Bernhard; I didn't check the
addressing.

Let us know how things go.

PS Any ideas on my post?

On Fri, 09 Jul 2004 22:16:56 +0200, "Bernhard Dobbels"
[off-list ref] said:

quoted

quoted

<snip>

quoted

quoted

viking:/home/bernhard# cat /etc/raidtab
raiddev /dev/md0
         raid-level      5
         nr-raid-disks   3
         nr-spare-disks  0
         persistent-superblock   1
         parity-algorithm        left-symmetric

         device  /dev/hdc1
         raid-disk 0
         device  /dev/hde1
         failed-disk 1
         device  /dev/hdg1
         raid-disk 2

Hmm. So the array is c+e+g, which think they are spare, failed, and
good, respectively.
The array won't be accessible unless at least two are good.

I wonder if running mkraid with --really-force when e was marked failed
was a good idea; hopefully it didn't make things worse. 

quoted

quoted

viking:/home/bernhard# mkraid --really-force /dev/md0
DESTROYING the contents of /dev/md0 in 5 seconds, Ctrl-C if unsure!
handling MD device /dev/md0
analyzing super-block
disk 0: /dev/hdc1, 195358401kB, raid superblock at 195358336kB
disk 1: /dev/hde1, failed
disk 2: /dev/hdg1, 195358401kB, raid superblock at 195358336kB
/dev/md0: Invalid argument

viking:/home/bernhard# raidstart /dev/md0
/dev/md0: Invalid argument


viking:/home/bernhard# cat /proc/mdstat
Personalities : [raid1] [raid5]
md0 : inactive hdg1[2] hdc1[0]
       390716672 blocks
unused devices: <none>
viking:/home/bernhard# pvscan -v
     Wiping cache of LVM-capable devices
     Wiping internal cache
     Walking through all physical volumes
   Incorrect metadata area header checksum
   Found duplicate PV uywoDlobnH0pbnr09dYuUWqB3A5kkh8M: using /dev/hdg1 
not /dev/hdc1
   Incorrect metadata area header checksum
   Incorrect metadata area header checksum
   Incorrect metadata area header checksum
   Found duplicate PV uywoDlobnH0pbnr09dYuUWqB3A5kkh8M: using /dev/hdg1 
not /dev/hdc1
   PV /dev/hdc1   VG data_vg   lvm2 [372,61 GB / 1,61 GB free]
   PV /dev/hda1                lvm2 [4,01 GB]
   Total: 2 [376,63 GB] / in use: 1 [372,61 GB] / in no VG: 1 [4,01 GB]

Yow.  

I'm wondering if editing raidtab to make e (/dev/hde1) not failed and
trying mkraid again is a good idea.

Any idea why c would think it was a spare?  That's pretty strange.

Anyway, I'm no expert - I just posted a call for help:
 
http://marc.theaimsgroup.com/?l=linux-raid&m=108932298006669&w=2 

that went unanswered.