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Date: Wed, 07 Aug 2013 23:08:24 +0100
From: Frank Leonhardt <frank2@fjl.co.uk>
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Subject: Re: Terrible disk performance with LSI / FreeBSD 9.2-RC1
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On 07/08/2013 21:36, J David wrote:
> It feels like some sort of issue with the
> bus/controller/kernel/driver/ZFS that is affecting all the drives
> equally.
>
> Also, even ls takes forever (10-30 seconds for "ls -lh /") but when it
> eventually does finish, "time ls -lh /" reports:
>
>          0.02 real         0.00 user         0.00 sys
>
> Really not sure what to make of that. An attempt to do "ps axlww |
> fgrep ls" while the ls was running failed, because the ps hangs just
> as long as the ls.  So it's like the system is just repeatedly putting
> anything that touches the disks on hold, even if all the data being
> requested is clearly in cache.  (Even apparently loading the binary
> for /bin/ls or doing "ls -lh /" twice in a row.)

As a suggestion, what happens if you read from the drives directly? Boot 
in single user and try reading a Gb or two using /bin/dd. It might 
eliminate or confirm a problem with ZFS.

Regards, Frank.