[CentOS] Re: Help repairing a broken Software Raid5

[Scott Silva]

Andrew @ ATM Logic spake the following on 7/6/2007 4:39 AM:
>> Hi,
>> Can you explain what have you tried till now? All I can say 
>> "man mdamd" is sufficient.
>>
>> --
>> Regards,
>> Sudev Barar
>> _______________________________________________
>> CentOS mailing list
>> CentOS at centos.org
>> http://lists.centos.org/mailman/listinfo/centos
>>
> 
> 
> 
> These are a few of the commands I have ran so far...
> 
> cat /proc/mdstat
> Personalities : [raid0] [raid1] [raid5] [raid6]
> Md1 : active raid1 hdd1[2] hdc1[1] hda1[0]
> 	104320 blocks [3/3] [UUU]
> 
> 
> (Just so you know... That's missing the "needed" MD2)
> 
> lvm pvscan
> 	- No matching physical volumes found
> lvm lvscan
> 	- No volume groups found
> lvm vgscan
> 	-  Reading all physical volumes.  This may take a while....
> 	No volume groups found
> 
> lvm vgchange -ay
> 	No volume groups found
> 
> lvm vgdisplay
> 	No volume groups found
> 
> 
> 
> fdisk -l /dev/hda
> Disk /dev/hda: 160.0 GB, 160041885696 bytes
> 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 *
> 512 = 8225280 bytes
> 
> 	Device Boot	Start	End	Blocks	Id System
> /dev/hda1	*	1	13	104391	fd	Linux raid
> autodetect
> /dev/hda2		14	19457	156183930	fd	Linux raid
> autodetect
> 
> fdisk -l /dev/hdc
> Disk /dev/hdc: 160.0 GB, 160041885696 bytes
> 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 *
> 512 = 8225280 bytes
> 
> 	Device Boot	Start	End	Blocks	Id System
> /dev/hdc1	*	1	13	104391	fd	Linux raid
> autodetect
> /dev/hdc2		14	19457	156183930	fd	Linux raid
> autodetect
> 
> fdisk -l /dev/hdd
> Disk /dev/hdd: 160.0 GB, 160041885696 bytes
> 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 *
> 512 = 8225280 bytes
> 
> 	Device Boot	Start	End	Blocks	Id System
> /dev/hdd1	*	1	13	104391	fd	Linux raid
> autodetect
> /dev/hdd2		14	19457	156183930	fd	Linux raid
> autodetect
> 
> 
>  raidstart /dev/md1
>  	-	No errors, just returns command prompt
>  
>  raidstart /dev/md2
>  	-	No errors, just returns command prompt
> 
> 
> 
> 
> Sooooooooo,  Then I tried to start fixing things.....
> 
>       mdadm --assemble -m 2 /dev/md2 /dev/hda2 /dev/hdc2 /dev/hdd2
> 
> I get
> Mdadm: Bad super-minor number: /dev/md2
> 
>       mdadm --assemble --run -m 2 /dev/md2 /dev/hda2 /dev/hdc2 /dev/hdd2
>  
> 
> Mdadm: failed to RUN_ARRAY /dev/md2: Invalid argument
> 
> Then... Looking at 
> 
> cat /proc/mdstat
> 
> Personalities : [raid0] [raid1] [raid5] [raid6]
> Md1 : active raid1 hdd1[2] hdc1[1] hda1[0]
> 	104320 blocks [3/3] [UUU]
> 
> Md2 : inactive hdc2[1] hdd2[2]
> 	312367616
> Unused devices: <none>
> 
> 
> Then... Trying to get a little more pushy...
> 
>  mdadm --stop /dev/md2
>  mdadm --verbose --assemble --run -m 2 /dev/md2 /dev/hda2 /dev/hdc2
> /dev/hdd2
> 
> Mdadm: looking for devices for /dev/md2
> Mdadm: /dev/hda2 is identified as a member of /dev/md2, slot 0
> Mdadm: /dev/hdc2 is identified as a member of /dev/md2, slot 1
> Mdadm: /dev/hdd2 is identified as a member of /dev/md2, slot 2
> Mdadm: added /dev/hda2 to /dev/md2 as 0
> Mdadm: added /dev/hdd2 to /dev/md2 as 2
> Mdadm: added /dev/hdc2 to /dev/md2 as 1
> Mdadm: failed to RUN_ARRAY /dev/md2: Invalid argument
> 
> 
> Ok... So... That is where I quit...    Any Idea what kind of hope I should
> be holding out for?
I recently had luck with the following on an array that wouldn't start after
the system was unplugged.
mdadm --assemble --run --force --update=summaries /dev/"raid array"
/dev/"drive1" /dev/"drive2" /dev/"drive3"

remember to fix the quoted parts with your actual entries.


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