Date: Tue, 28 Sep 2010 08:44:44 -0400 From: Stephen Sanders <ssanders@softhammer.net> To: freebsd-performance@freebsd.org Subject: Re: gstripe small transaction size Message-ID: <4CA1E33C.70200@softhammer.net> In-Reply-To: <i7sguk$gi2$1@dough.gmane.org> References: <4CA14009.4050906@softhammer.net> <i7sguk$gi2$1@dough.gmane.org>
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Increasing MAXPHYS and turning up the stripe size won't have the effect I'm looking for ? I see where MAXPHYS is now a kernel configuration parameter in FreeBSD 8.1. Thanks. On 09/28/2010 06:44 AM, Ivan Voras wrote: > On 09/28/10 03:08, Stephen Sanders wrote: >> 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 ? >> >> gstripe label -v -s 131072 roadkill /dev/da0 /dev/da2 > > No pratical way. You have a gstripe array of two drives and with > MAXPHYS of 128 KiB each would in fact see at most 64 KiB transactions. > It gets worse when you add drives. > >> newfs /dev/stripe/roadkill > > Depending on what you are doing, adding "-U" would help you here. > > > _______________________________________________ > freebsd-performance@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-performance > To unsubscribe, send any mail to > "freebsd-performance-unsubscribe@freebsd.org" >
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