# Strange resilver speed



## gpeskens (Aug 21, 2012)

Currently I'm resilvering one of my drives after replacing it, I've been monitoring the process most of the time and right now I'm starting to see really strange resilver speeds:
according to zpool status the speed is around 500M/s, while iostat shows no more than 20M combined.

Is this due to the zpool command displaying resilver speed relative to the whole pool size and the actual scanning only occurring at existing data ? (it's at 2.9TB out of 4.14 with disk usage round 2.7TB) ?


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## Sebulon (Aug 23, 2012)

@gpeskens

ItÂ´s showing an average during the entire time of the scrub and "normalizes" as it goes. To see the real average, you would need to run "zpool status" a couple of minutes before itÂ´s completed. The scanning speed can vary during the scrub, from down to less than 1MB/s to up to GB/s, dependent on your HW of course. It mainly has to do with what itÂ´s scanning at the time. Dedup e.g. can slow down scrubbing to under 1MB/s.

/Sebulon


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