the question is: does the "IO pausing" behaviour you noticed penalize
what are the consequences at the application level?
for instance we have seen application doing some kind of data capture
from external device (video for example) requiring a constant
throughput to disk (data feed), risking otherwise loss of data. in
this case qfs might be a better option (no free though)
if your application is not suffering, then you should be able to live
with this apparent "io hangs"
On Thu, Mar 27, 2008 at 3:35 AM, Bob Friesenhahn
> My application processes thousands of files sequentially, reading
> input files, and outputting new files. I am using Solaris 10U4.
> While running the application in a verbose mode, I see that it runs
> very fast but pauses about every 7 seconds for a second or two. This
> is while reading 50MB/second and writing 73MB/second (ARC cache miss
> rate of 87%). The pause does not occur if the application spends more
> time doing real work. However, it would be nice if the pause went
> I have tried turning down the ARC size (from 14GB to 10GB) but the
> behavior did not noticeably improve. The storage device is trained to
> ignore cache flush requests. According to the Evil Tuning Guide, the
> pause I am seeing is due to a cache flush after the uberblock updates.
> It does not seem like a wise choice to disable ZFS cache flushing
> entirely. Is there a better way other than adding a small delay into
> my application?
> Bob Friesenhahn
> bfriesen@xxxxxxxxxxxxxxxxxxx, http://www.simplesystems.org/users/bfriesen/
> GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
> zfs-discuss mailing list
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