[olug] Software RAID / accidentally raidhotadd to wrong md

[Terry]

Ok...no guarentees here......

Answer #1 - No, you should be able to recover from
this.
Answer #2 - Read below....

- Assuming /dev/md2 is started
umount /dev/md2
raidhotremove /dev/md2 /dev/hdb2
raidhotremove /dev/md2 /dev/hdc2
mount /dev/md2

That should take the drives out of md2...and take the
references out of the superblock.  Do this and reboot 
(just to be thorough)...you might want to comment
their references from fstab if you can....also single
user mode might be best here too.....

Also, paste your fstab of the relevant devices so I
don't tell you to do something completely stupid (if I
havent already, haha).

dont do a mkraid --really-force as that will wipe out
your data.  There are some tricks with mkraid you can
do to rebuild the superblock but i have never had to
do that so I am not going to recommend that to you at
this point, has to do with a --failed-disk paramater I
think.

May the force be with you....(god, no, not --force!)
:)


--- lug at robotz.com wrote:
> I will type it in here....
> 
> /etc/raidtab
> 
> raiddev			/dev/md3
> raid-level		5
> nr-raid-disks		3
> chuck-size		64k
> oersustebt-superblock	1
> nr-spare-disks		0
> 
> device			/dev/hda3
> raid-disk		0
> device			/dev/hdb3
> raid-disk		1
> device			/dev/hdc3
> raid-disk		2
> 
> raiddev			/dev/md0
> raid-level		1
> nr-raid-disks		3
> chuck-size		64k
> oersustebt-superblock	1
> nr-spare-disks		0
> 
> device			/dev/hda1
> raid-disk		0
> device			/dev/hdb1
> raid-disk		1
> device			/dev/hdc1
> raid-disk		2
> 
> raiddev			/dev/md4
> raid-level		5
> nr-raid-disks		3
> chuck-size		64k
> oersustebt-superblock	1
> nr-spare-disks		0
> 
> device			/dev/hda2
> raid-disk		0
> device			/dev/hdb2
> raid-disk		1
> device			/dev/hdc2
> raid-disk		2
> 
> raiddev			/dev/md2
> raid-level		5
> nr-raid-disks		3
> chuck-size		64k
> oersustebt-superblock	1
> nr-spare-disks		0
> 
> device			/dev/hda5
> raid-disk		0
> device			/dev/hdb5
> raid-disk		1
> device			/dev/hdc5
> raid-disk		2
> 
> raiddev			/dev/md1
> raid-level		5
> nr-raid-disks		3
> chuck-size		64k
> oersustebt-superblock	1
> nr-spare-disks		0
> 
> device			/dev/hda6
> raid-disk		0
> device			/dev/hdb6
> raid-disk		1
> device			/dev/hdc6
> raid-disk		2
> 
> 
> 
> 
> At Wednesday, 31 March 2004, you wrote:
> 
> >Wow, paste your raidtab if you don't mind....let me
> >take a peek at that then read your stuff below. 
> That
> >will help....
> >
> >--- lug at robotz.com wrote:
> >> Issue summary:  Had problems with 1 of a 3 drive
> >> software raid array.
> >> Harddrive is not physically bad, but the array
> >> failed today on boot.
> >> Used “raidhotadd” to get all of the raid5
> partitions
> >> (md0 – md3) 
> >> up and running with the exception of the most
> >> important partition 
> >> (md4).
> >> 
> >> I accidentally tried to “raidhotadd” 2 of the 3
> >> drives from md4 into 
> >> md2.  Now hdb2 and hdc2 think they are part of
> md2
> >> when they actually 
> >> should be part of md4.  This is not reflected in
> >> /etc/raidtab but 
> >> must be stored somewhere I cannot find.
> >> (superblock?)
> >> 
> >> This leaves only 1 drive in md4 and therefore md4
> >> will not start 
> >> even degraded.  md4 is a RAID 5 partition, which
> is
> >> supposed to include 
> >> hda2, hdb2, and hdc2.  Since RAID wont start on
> md4,
> >> I cannot simply 
> >> use “raidhotremove” and “raidhotadd” to correct
> this
> >> mistake (assuming 
> >> that would correct the mistake).
> >> 
> >> I used “raidsetfaulty” to deactivate hdb2 to stop
> >> interfering with 
> >> the start of md2.  (because hdb2 belongs in md4
> and
> >> raidhotremove 
> >> refuses to get hdb2 out of md2 without
> deactivating
> >> the partition)
> >> 
> >> lsraid reports md0 – md3 correctly.  However,
> typing
> >> “lsraid –A –d 
> >> /dev/hdb2” or “lsraid –A –d /dev/hdc2” shows them
> as
> >> a member of 
> >> md2 still.  They should be in md4 instead.
> >> 
> >> My question #1:  Did my mistake hose the data in
> >> both hdb2 and hdc2 
> >> making it impossible to recover md4 (my most
> >> critical partition containing 
> >> /home) or is hdb2 and hdc2 merely confused about
> >> where they belong 
> >> but still within them is my critical data making
> >> recovery of md4 
> >> possible?
> >> 
> >> My question #2: If recovery is possible, should I
> >> then “mkraid /dev/md4 
> >> –f” and hope for the best or is there a safer way
> to
> >> _save_ my data? 
> >> Or perhaps there is a way to make hdb2 and hdc2
> >> realize again that 
> >> they are part of md4.   
> >> 
> >> Keep in mind that since md4 won’t start I can’t
> >> reverse the mistake 
> >> with raidhotadd.
> >> 
> >> If I failed to provide any details please let me
> >> know and I will 
> >> elaborate further.
> >> 
> >> Thank you.
> >> 
> >> 
> >> 
> >> 
> >> 
> >> 
> >> 
> >> _______________________________________________
> >> OLUG mailing list
> >> OLUG at olug.org
> >> http://lists.olug.org/mailman/listinfo/olug
> >
> >=====
> >Terry
> >
> >__________________________________
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> 
> 
> 
> 
> 
> 
> 
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=====
Terry

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