Hi Edward,

From: 
zfs-discuss-boun...@opensolaris.org<mailto:zfs-discuss-boun...@opensolaris.org> 
[mailto:zfs-discuss-
boun...@opensolaris.org<mailto:boun...@opensolaris.org>] On Behalf Of Koopmann, 
Jan-Peter
all I can tell you is that I've had terrible scrub rates when I used dedup.

I can tell you I've had terrible everything rates when I used dedup.

I am not alone then. Thanks! :-)

Only two of my datasets were deduped. On scrubs and
resilvers I noticed that sometimes I had terrible rates with < 10MB/sec. Then
later it rose up to < 70MB/sec. After upgrading some discs (same speeds
observed) I got rid of the deduped datasets (zfs send/receive them) and
guess what: All of the sudden scrub goes to 350MB/sec steady and only take
a fraction of the time.

Are you talking about scrub rates for the complete scrub?  Because if you sit 
there and watch it, from minute to minute, it's normal for it to bounce really 
low for a long time, and then really high for a long time, etc.  The only 
measurement that has any real meaning is time to completion.



Well both actually. The lowest rate I observed increased significantly without 
dedup and the time to completion decreased a lot as well. I remember doing a 
scrub after a resilver that took appr. 20-24 hours. Last scrub without dedup 
3:26. :-) A LOT FASTER….


Kind regards,
   JP
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