Re: 1 week to rebuid 4x 3TB raid10 is a long time!

[Wang Shilong <wangsl.fnst@cn.fujitsu.com>]

Hi,

On 07/20/2014 04:45 PM, TM wrote:
> Hi,
>
> I have a raid10 with 4x 3TB disks on a microserver
> http://n40l.wikia.com/wiki/Base_Hardware_N54L , 8Gb RAM
>
> Recently one disk started to fail (smart errors), so I replaced it
> Mounted as degraded, added new disk, removed old
> Started yesterday
> I am monitoring /var/log/messages and it seems it will take a long time
> Started at about 8010631739392
> And 20 hours later I am at 6910631739392
> btrfs: relocating block group 6910631739392 flags 65
>
> At this rate it will take a week to complete the raid rebuild!!!
Just my two cents:

Since 'btrfs replace' support RADI10, I suppose using replace
operation is better than 'device removal and add'.

Another Question is related to btrfs snapshot-aware balance.
How many snapshots did you have in your system?

Of course, During balance/resize/device removal operations,
you could still snapshot, but fewer snapshots should speed things up!

Anyway 'btrfs replace' is implemented more effective than
'device remova and add'.:-)

Thanks,
Wang
>
> Furthermore it seems that the operation is getting slower and slower
> When the rebuild started I had a new message every half a minute, now it’s
> getting to OneAndHalf minutes
> Most files are small files like flac/jpeg
>
> One week for a raid10 rebuild 4x3TB drives is a very long time.
> Any thoughts?
> Can you share any statistics from your RAID10 rebuilds?
>
> If I shut down the system, before the rebuild, what is the proper procedure
> to remount it? Again degraded? Or normally? Can the process of rebuilding
> the raid continue after a reboot? Will it survive, and continue rebuilding?
>
> Thanks in advance
> TM
>
>
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