RE: RAID 5 array recovery - two drives errors in external enclosure

["Guy Watkins" <linux-raid@watkins-home.com>]

I think the order of your drives changed.  But I don't know how.  You should
not have done another create, because it destroys the superblocks.  You
should have done an assemble, listing all drives and not using missing.  Md
should find all the correct drives.  Or if it said 1 was wrong, just try
again and don't list that one.

Anyway, glad you got your data.

} -----Original Message-----
} From: Tim Bostrom [mailto:tbostrom@gmail.com]
} Sent: Monday, September 21, 2009 12:41 AM
} To: Guy Watkins
} Cc: Tom Carlson; Majed B.; linux-raid
} Subject: Re: RAID 5 array recovery - two drives errors in external
} enclosure
} 
} Well, thank god I copied everything off the array this weekend, but
} strange:
} 
} I had gotten the array up finally with the correct order and missing
} drive:
} 
} mdadm -C /dev/md0 -l 5 -n 5 -c 256 /dev/sdf1 /dev/sdc1 /dev/sdb1
} /dev/sdd1 missing
} 
} ------------
} After copying everything off, I power-cycled my server and tried to
} bring the array back up again using:
} 
} mdadm -A /dev/md0 /dev/sdf1 /dev/sdc1 /dev/sdb1 /dev/sdd1 missing
} 
} I received the error : mdadm: superblock on /dev/sdc1 doesn't match
} others - assembly aborted.
} 
} This is strange since I had this seemingly working and was able to
} copy all the data offline this weekend.
} Drives haven't changed order - I haven't unplugged anything or changed
} any cords.
} 
} Another issue of the command that worked before on the array:
} mdadm -C /dev/md0 -l 5 -n 5 -c 256 /dev/sdf1 /dev/sdc1 /dev/sdb1
} /dev/sdd1 missing
} 
} yields my old problem of not being able to mount.
} EXT3-fs: md0: couldn't mount because of unsupported optional features
} (3fd18e00).
} mount: wrong fs type, bad option, bad superblock on /dev/md0,
}        missing codepage or helper program, or other error
}        In some cases useful info is found in syslog - try
}        dmesg | tail  or so
} 
} What gives?  The drive order couldn't have changed just through a
} reboot.   All the same number of drives and drive letters are there.
} 
} 
} -Tim
} 
} 
} 
} On Fri, Sep 18, 2009 at 6:35 PM, Guy Watkins <guy@watkins-home.com> wrote:
} > If you are starting over, maybe you should use RAID6?
} >
} > } -----Original Message-----
} > } From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
} > } owner@vger.kernel.org] On Behalf Of Tom Carlson
} > } Sent: Friday, September 18, 2009 9:18 PM
} > } To: Majed B.
} > } Cc: Tim Bostrom; linux-raid
} > } Subject: Re: RAID 5 array recovery - two drives errors in external
} > } enclosure
} > }
} > } 2009/9/19 Majed B. <majedb@gmail.com>:
} > } > If you're going to take all your data out, I would suggest you do a
} > } > clean start and zero out all the disks to force the remapping of bad
} > } > sectors, then run smartctl -t offline on all disks and after it's
} done
} > } > (it will take A LONG time), create your filesystem on an array and
} put
} > } > back your data.
} > }
} > } I'd recommend running the badblocks program on each device to be put
} > } in the array too, just to be certain that none of your disks are going
} > } to go horribly flakey on assembly and build... I'm not sure if the
} > } offline smart test does a full scan like badblocks would.
} > }
} > } T
} > } --
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} >
} >
} 
} 
} 
} --
} -tim

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