Date: Mon, 27 Sep 2010 21:08:25 -0400 From: Stephen Sanders <ssanders@softhammer.net> To: freebsd-performance@freebsd.org Subject: gstripe small transaction size Message-ID: <4CA14009.4050906@softhammer.net>
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I'm trying a disk throughput experiment where in two 3ware raid 6's are being put into a g_strip raid 0. The raid 6's are using 8 7200RPM disks. The disk transfer rate is ~80MB/s. Using a load generation tool that is using O_DIRECT for I/O, I've generated the following short output from iostat. Needless to say, the write performance is a lot less than I'm expecting. We've modified the kernel such that our KB/t figure is closer to 512KB/t per disk when measured without the g_strip. With g_strip turned on, the KB/t number is more like 60KB/t. The question is how do I get g_stripe to write larger transactions to the disk ? Thanks. gstripe label -v -s 131072 roadkill /dev/da0 /dev/da2 newfs /dev/stripe/roadkill mount /dev/stripe/roadkill /u8 sysctl kern.geom.stripe.fast=1 iostat -n3 -t da 5 tty da0 da1 da2 cpu tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id 0 200 39.52 13 0.49 11.97 1 0.01 41.23 12 0.49 0 0 0 0 100 0 47 0.00 0 0.00 0.00 0 0.00 0.00 0 0.00 0 0 0 0 100 1 19 0.00 0 0.00 0.00 0 0.00 0.00 0 0.00 0 0 0 0 100 20 47 0.00 0 0.00 41.43 3 0.11 0.00 0 0.00 0 0 0 0 100 0 18 56.60 1817 100.41 20.00 1 0.02 57.22 1797 100.44 0 0 6 1 93 0 16 58.87 1978 113.73 0.00 0 0.00 58.27 2000 113.81 0 0 6 1 92 0 16 60.38 1906 112.37 16.00 0 0.00 59.95 1918 112.31 0 0 7 1 92 0 16 59.36 1863 108.01 0.00 0 0.00 60.00 1844 108.07 0 0 6 1 93 0 16 59.88 1933 113.05 0.00 0 0.00 60.40 1915 112.98 0 0 7 1 92
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