Re: RAID50 boot problems

[Roy Sigurd Karlsbakk <roy@karlsbakk.net>]

----- Opprinnelig melding -----
> Hi,
> 
> I have almost working RAID50 (two RAID5 forms RAID0) in my
> Linux-mint13. When booting the system always ends up in initramfs
> shell, saying it cannot find the "root". When I type "cat
> /proc/mdstat" I see that both RAID5 are available, but they did not
> form RAID0. So I do "mdadm -A --scan" to finish the raid creation.
> After that I can exit the initramfs shell and system finishes booting
> (and works later) without any problems. Of course initramfs image is
> in sync with root (/etc/mdadm/mdadm.conf file is the same in initramfs
> and rootfs).
> This is what my system is using:
> kernel 3.5.0-26-generic
> mdadm - v3.2.5 - 18th May 2012
> 
> To summarize, I have RAID50 which _almost_ works. It just needs to be
> pushed/kicked during the boot. Could you advise my how can I
> automatize the process, so I do not need to type "mdadm -A
> --scan;exit" every time I switch on my computer?

Interesting… I have an ubuntu 13.04 VM for just raid testing, and I tried this configuration. I created two RAID-5s here and then a RAID-0 on top of those. I yet haven't put a filesystem on it. I just wanted to see if I could reproduce your issue, and I can.

It seems what happens is it only runs an initial scan, and then just finding the raids on physical (or otherwise) disks. In my case, md9 won't be available before md0 and md1 are started. I solved this by adding a line to /etc/rc.local

# If using nested MD, such as RAID5+0, another scan is needed
mdadm --assemble --scan

See below for full logs.

roy

root@raidtest:~# mdadm --detail --scan >> /etc/mdadm/mdadm.conf
(edit mdadm.conf to remove old entries)
root@raidtest:~# update-initramfs -u 
update-initramfs: Generating /boot/initrd.img-3.8.0-18-generic
root@raidtest:~# cat /proc/mdstat 
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md9 : active raid0 md0[0] md1[1]
      4191232 blocks super 1.2 512k chunks
      
md1 : active raid5 vde[0] vdg[3] vdf[1]
      2096000 blocks super 1.2 level 5, 64k chunk, algorithm 2 [3/3] [UUU]
      
md0 : active raid5 vdd[3] vdc[1] vdb[0]
      2096000 blocks super 1.2 level 5, 64k chunk, algorithm 2 [3/3] [UUU]
      
unused devices: <none>

root@raidtest:~# reboot
...
root@raidtest:~# cat /proc/mdstat 
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md0 : active raid5 vdd[3] vdc[1] vdb[0]
      2096000 blocks super 1.2 level 5, 64k chunk, algorithm 2 [3/3] [UUU]
      
md1 : active raid5 vdg[3] vde[0] vdf[1]
      2096000 blocks super 1.2 level 5, 64k chunk, algorithm 2 [3/3] [UUU]
      
unused devices: <none>
root@raidtest:~# 

-- 
Vennlige hilsener / Best regards

roy
--
Roy Sigurd Karlsbakk
(+47) 98013356
roy@karlsbakk.net
http://blogg.karlsbakk.net/
GPG Public key: http://karlsbakk.net/roysigurdkarlsbakk.pubkey.txt
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