RE: messed up changing chunk size

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

No idea, but I would not risk it.  Let it finish, unless someone else has a
useful tip.

} -----Original Message-----
} From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
} owner@vger.kernel.org] On Behalf Of Konstantin Svist
} Sent: Sunday, July 18, 2010 9:46 PM
} To: linux-raid@vger.kernel.org
} Subject: Re: messed up changing chunk size
} 
}   Right now the reshape is at "32.1% (94138368/293033472)
} finish=861.4min speed=3847K/sec"
} Is it safe to reshape back right now, will it pick up the command?
} 
} On 07/18/2010 06:29 PM, Guy Watkins wrote:
} > I think this should work:
} > Put the chunk size back, resize the array to the original size, then run
} > fsck and hope it did not need the data on the end that got trashed.
} Then
} > shrink your file system first (by a really safe margin), then resize the
} > array, then change chunk size.  Then grow the file system to use the max
} > allowed.
} >
} > Maybe the data on the end did not get trashed, but I don't know.
} >
} >
} > } -----Original Message-----
} > } From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
} > } owner@vger.kernel.org] On Behalf Of Konstantin Svist
} > } Sent: Sunday, July 18, 2010 8:32 PM
} > } To: linux-raid@vger.kernel.org
} > } Subject: messed up changing chunk size
} > }
} > }   I've been playing around with RAID config and may have finally
} messed
} > } it up.
} > }
} > } Initially, I created the array with 3 300G drives:
} > } # mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3
} /dev/sda4
} > } /dev/sdb1 /dev/sdc1
} > } # mkfs.ext4 -v -m 0.01 -E stride=16,stripe-width=32 /dev/md0
} > }
} > } It's been working nicely so far, and I decided to add a 4th 300G
} drive:
} > } # mdadm --grow --raid-devices=4 --backup-file=/root/grow_md0.bak
} /dev/md0
} > }
} > } That finished overnight, while I looked around and found that chunk
} size
} > } of 512 should work better. I unmounted the FS and ran
} > } # mdadm --grow -c 512 --backup-file=/root/grow_md0_rechunk.bak
} /dev/md0
} > } mdadm: component size 293033536K is not a multiple of chunksize 512K
} > }
} > } so I sized it down a bit:
} > } # mdadm --grow -z 293033472 --backup-file=/root/grow_md0_size.bak
} /dev/md0
} > }
} > } and then back to resizing chunks:
} > } mdadm --grow -c 512 --backup-file=/root/grow_md0_rechunk.bak /dev/md0
} > }
} > } It's running right now:
} > } # cat /proc/mdstat
} > } Personalities : [raid6] [raid5] [raid4]
} > } md0 : active raid5 sdd1[3] sda4[0] sdc1[2] sdb1[1]
} > }        293033472 blocks super 0.91 level 5, 64k chunk, algorithm 2
} [4/4]
} > } [UUUU]
} > }        [====>................]  reshape = 22.7% (66540032/293033472)
} > } finish=947.3min speed=3984K/sec
} > }
} > }
} > } But just now I tried to mount the filesystem and it's failing:
} > } EXT4-fs (md0): bad geometry: block count 146516768 exceeds size of
} > } device (73258368 blocks)
} > }
} > } Here's the question, then: am I royally screwed or is my data still
} > } there? How do I recover?
} > }
} > }
} > }
} > } Yes, in retrospect I should've probably checked around whether this
} > } process has been successful for others.. but that's why they say
} > } hindsight is 20/20
} > }
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} >
} 
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