Date: Sat, 28 Aug 1999 00:15:28 +0300 From: Evren Yurtesen <yurtesen@ispro.net.tr> To: dg@root.com Cc: chas <panda@skinnyhippo.com>, freebsd-questions@FreeBSD.ORG Subject: Re: how can you tell when disk i/o is limiting performance ? Message-ID: <37C6FFEF.7E7E6F38@ispro.net.tr> References: <199908272043.NAA06339@implode.root.com>
next in thread | previous in thread | raw e-mail | index | archive | help
I believe that since tps and that kind of stuff is depending on the drive you cant say you are at the limits when your system shows 120 tps etc. I think you should use a benchmarking program when your system is idle to find out your limits and then compare them with the actual load. see the benchmark programs... http://www.freebsd.org/ports/benchmarks.html About the disks, it is better to have more disks if you are using a scsi system since the operating system can access to more than 1 scsi drives simultaneously which is you cant do with ide drives. For example if you have 2 scsi drives you may see that FreeBSD is checking both of them at the same time when you are booting from their leds etc. David Greenman wrote: > >Is there any method to measure disk I/O, in particular to > >work out if it is limiting performance ? > > > >Context : > >1 x 18 GB SCSI HD (10,000 RPM) > > > >Each day : > >200,000 x CGI processes, each reading 2 or 3 flat files > >100,000 x CGI processes, each reading/writing to mysql database > >1,000,000+ x flat files (images, .html etc) > > > >plus 400 MB+ of apache log files are created each day. > > > >There seems to be ample RAM and CPU (and we're not even going > >into swap) but the website is really crawling. I realise that > >this could be due to the poor bandwidth in China (where the > >server is hosted) but would like to also monitor the disk i/o > >if it's possible since the CGIs open a lot of files and the apache > >log files are being written nonstop. > > > >Hopefully then I can plan/budget for more disks and/or a second > >server as traffic reaches a threshold. > > > >So : > >a) can this be measured ? (i.e how do you know when your disk i/o is > > the limiting factor ? ) > > Use "systat -iostat". Look at the TPS rates for each disk drive. Modern > disk drives top out at around 80-120 TPS. > > >b) would it make more sense to have 3 separate (physical) disks for : > > - apache log files > > - mysql database > > - operating system, applications, website files/cgi > > Yes, more disks is better. > > -DG > > David Greenman > Co-founder/Principal Architect, The FreeBSD Project - http://www.freebsd.org > Creator of high-performance Internet servers - http://www.terasolutions.com > Pave the road of life with opportunities. > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?37C6FFEF.7E7E6F38>