zpool scrub speed

Jason J. W. Williams jasonjwwilliams at gmail.com
Fri May 6 11:29:57 EDT 2011


Depends on how fragmented the volume is and how much data is in the pool (it'll only scrub the amount of data in the pool as opposed to scrubbing freespace). Had to scrub an onv_131 system the other night...22x 7200rpm disks with 247gb of data took about 19mins. 

I've seen a 14 drive (7200rpm) pool with 1.8tb of data (raid-z2) take over a day to scrub due to failing disks. If you start to see lots of checksum errors on the drives you'll see a long scrub. 

-J

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On May 6, 2011, at 2:07, Gordan Bobic <gordan.bobic at gmail.com> wrote:

> What is the general performance expected from zfs scrub? I would have expected it to be in the region of the combined read speed of the data bearing disks (i.e. excluding the parity disks). But my 13 disk array only gets about 170MB/s on a scrub. Is this normal, i.e. explained by the disk-seeking required?
> 
> Gordan



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