RAID adventures

[Konstantin Svist]

  On 07/18/2010 08:03 PM, Bill Davidsen wrote:
> Konstantin Svist wrote:
>>    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?
> May I suggest trying this on the linux-raid list? Not that's it's off-topic
> here, just that people there may have faster/better answers.
>

Yeah, I thought of exactly the same thing after posting this message.