On Mon, Dec 19, 2011 at 11:58:57AM +0000, Jan-Aage Frydenbø-Bruvoll wrote:
> 2011/12/19 Hung-Sheng Tsao (laoTsao) <laot...@gmail.com>:
> > did you run a scrub?
> Yes, as part of the previous drive failure. Nothing reported there.
> Now, interestingly - I deleted two of the oldest snapshots yesterday,
> and guess what - the performance went back to normal for a while. Now
> it is severely dropping again - after a good while on 1.5-2GB/s I am
> again seeing write performance in the 1-10MB/s range.

That behavior is a symptom of fragmentation.  Writes slow down
dramatically when there are no contiguous blocks available.  Deleting
a snapshot provides some of these, but only temporarily.

-Gary Mills-            -refurb-                -Winnipeg, Manitoba, Canada-
zfs-discuss mailing list

Reply via email to