Date: Sat, 17 Sep 2011 10:54:34 -0700 From: "David P. Discher" <dpd@bitgravity.com> To: Lytochkin Boris <lytboris@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: [ZFS] starving reads while idle disks Message-ID: <6B437FA4-B422-4BE7-BDF5-F90717F3865B@bitgravity.com> In-Reply-To: <CAEJYa-Si%2B4Tj5sj8fuxWfqjZgMX1cB8y=JWqJqe_F%2BR4Er9g_A@mail.gmail.com> References: <CAEJYa-Si%2B4Tj5sj8fuxWfqjZgMX1cB8y=JWqJqe_F%2BR4Er9g_A@mail.gmail.com>
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Do you see the same read-stravation when writing the tar to a file ? = (possibly outside the zpool). I have anecdotal suspicion that /dev/null has some performance hit of = blocking or locking.=20 -dpd On Sep 17, 2011, at 5:02 AM, Lytochkin Boris wrote: > While runnig `tar cf - . >/dev/null', `vmstat -i' shows ~200 > interrupts per second for mpt. If I enable scrub on that pool, > interrupts bump upto 5k ips resulting 12Mb/s scrub speed and disks > busy percentage raises upto 100%. No warnings are shown in logs in > both cases.
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