Date: Thu, 30 Aug 2007 20:22:30 -0500 From: Eric Anderson <anderson@freebsd.org> To: Scott Long <scottl@samsco.org> Cc: FREEBSD - SCSI - LIST <freebsd-scsi@freebsd.org> Subject: Re: performance with LSI SAS 1064 Message-ID: <46D76D56.5070007@freebsd.org> In-Reply-To: <46D6D9C3.6050202@samsco.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> <71d0ebb0708300737o4fc7966dj61cf0e68482da398@mail.gmail.com> <46D6D9C3.6050202@samsco.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Scott Long wrote: > 54MB/s is reasonable for 10k 2.5" disks. You might be able to squeeze > some more performance by upgrading to FreeBSD 7.0. I _do_not_ recommend > playing with the queue depth controls unless your console logs are > getting quickly filled with messages about it. Yea, 55-65MB/s is about right for that drive.. Also, when I played with the tagged queue depth previously, I never had any issue, and it solved several SCSI (fabric/fiber channel thought) issues I was having. The performance didn't change measurably when changing it down to 64, but below that it did see a performance hit. Eric > Lutieri G. wrote: >> 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 >>> >>> >>> >>> >>> >> >> >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?46D76D56.5070007>