Date: Thu, 30 Aug 2007 11:37:12 -0300 From: "Lutieri G." <lutierigbtrabalho@gmail.com> To: "Eric Anderson" <anderson@freebsd.org> Cc: FREEBSD - SCSI - LIST <freebsd-scsi@freebsd.org> Subject: Re: performance with LSI SAS 1064 Message-ID: <71d0ebb0708300737o4fc7966dj61cf0e68482da398@mail.gmail.com> In-Reply-To: <46D6CB71.4030707@freebsd.org> References: <71d0ebb0708291245g79d2141fx73cc8a6e76875944@mail.gmail.com> <46D5E17F.3070403@samsco.org> <71d0ebb0708291416v17351c65u7ccc1b7bbe0271d2@mail.gmail.com> <46D5E5B1.207@samsco.org> <71d0ebb0708291506i49649a60l8006deafb20891ac@mail.gmail.com> <46D63710.1020103@freebsd.org> <71d0ebb0708300502x632fe83bo617f84ca2008dc7d@mail.gmail.com> <46D6BEC0.1050104@samsco.org> <46D6CB71.4030707@freebsd.org>
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This is my disks: Seagate Savvio(ST913401ss) 10K.1 SAS 3Gb/s 73-GB Hard Drive. In the manual file i found this information: Queue tagging (up to 64 queue tags supported) Is this the max # for setting using camcontrol?! syntax like this: camcontrol tags da0 -N 64 ?? 2007/8/30, Eric Anderson <anderson@freebsd.org>: > Scott Long wrote: > > Lutieri G. wrote: > >> 2007/8/30, Eric Anderson <anderson@freebsd.org>: > >>> I'm confused - you said in your first post you were getting 3MB/s, where > >>> above you show something like 55MB/s. > >> Sorry! using blogbench i got 3MB/s and 100% busy. Once is 100% busy i > >> thinked that 3MB/s is the maximum speed. But i was wrong... > > > > %busy is a completely useless number for a anything but untagged, > > uncached disk subsystems. It's only an indirect measure of latency, and > > there are better tools for measuring latency (gstat). > > > >>> You didn't say what kind of disks, or how many, the configuration, etc - > >>> so it's hard to answer much. The 55MB/s seems pretty decent for many > >>> hard drives in a sequential use state (which is what dd tests really). > >>> > >> SAS disks. Seagate, i don't know what is the right model of disks. > >> > >> Ok. If 55Mb/s is a decent speed i'm happy. I'm getting problems with > >> squid cache and maybe should be a problem related with disks. But... > >> i'm investigating and discharging problems. > >> > >> > >>> Your errors before were probably caused because your queue depth is set > >>> to 255 (or 256?) and the adapter can't do that many. You should use > >>> camcontrol to reduce it, to maybe 32. See the camcontrol man page for > >>> the right usage. It's something that needs setting on every boot, so a > >>> startup file is a good place for it maybe. > >>> > >> Is there any way of get the right number to reduce?! > >> > > > > If you're seeing erratic performance in production _AND_ you're seeing > > lots of accompanying messages on the console about tag depth jumping > > around, you can use camcontrol to force the depth to a lower number of > > you're choosing. This kind of problem is pretty rare, though. > > Scott, you are far more of a SCSI guru than I, so please correct me if > this is incorrect. Can't you get a good estimate, by knowing the queue > depth of the target(s), and dividing it by the number of initiators? So > in his case, he has one initiator, and (let's say) one target. If the > queue depth of the target (being the Seagate SAS drive) is 128 (see > Seagate's paper here: > http://www.seagate.com/staticfiles/support/disc/manuals/enterprise/savvio/Savvio%2015K.1/SAS/100407739b.pdf > ), then he should have to reduce it down from 25[56] to 128, correct? > > With QLogic cards connected to a fabric, I saw queue depth issues under > heavy load. > > Eric > > > > > -- Att. Lutieri G. B.
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