Re: messed up changing chunk size

[Konstantin Svist <fry.kun@gmail.com>]

  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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