zpool scrub speed

Uncle Stoatwarbler stoatwblr at gmail.com
Fri May 6 05:52:02 EDT 2011

On 06/05/11 09:07, Gordan Bobic 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?

I see about 150MB/s on a 5 2Tb disk array (Samsung 7200rpm) and about 90 
on a mirror set (Seagate Momentus XT drives - 2.5" 320Gb with 4Gb flash)

As far as I can tell, it's not cpu limited.

Iostat shows disk service times are substantially shorter than await 
times (ms vs tens of ms), but neither are excessive.

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