{"id":2658,"date":"2013-12-04T06:42:46","date_gmt":"2013-12-03T22:42:46","guid":{"rendered":"http:\/\/rmohan.com\/?p=2658"},"modified":"2013-12-04T06:42:46","modified_gmt":"2013-12-03T22:42:46","slug":"disk-performance-iostat","status":"publish","type":"post","link":"https:\/\/mohan.sg\/?p=2658","title":{"rendered":"Disk Performance   iostat"},"content":{"rendered":"<p>Use iostat to get the performance data<br \/>\n# iostat -x<\/p>\n<p>Device:       rrqm\/s   wrqm\/s   r\/s   w\/s       rsec\/s   wsec\/s   avgrq-sz avgqu-sz   await  svctm  %util<br \/>\nsda               0.48          2.76     1.90  0.92        56.44     29.40    30.53         0.01        4.48       2.46      0.69<\/p>\n<p>Work out the queue length<br \/>\nrequests * average wait time \/ 1000 = queue length<br \/>\n((1.90+0.92) * 4.48) \/ 1000 = 0.01<\/p>\n<p>Calculate the throughput<br \/>\nreads and writes * sector size<br \/>\n(56.44+29.40) * 512 \/ 1024 = 43Ki<\/p>\n<p>Calculate utilization<br \/>\nrequests * service time \/ 1000 * 100 = utilization<br \/>\n(1.90+0.92) * 2.46 \/ 1000 * 100 = 0.69 <\/p>\n<p>Determine peak arrival rate<br \/>\n1\/service time * 1000<br \/>\n(1\/2.46 )*1000 = 406.5<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Use iostat to get the performance data # iostat -x<\/p>\n<p>Device: rrqm\/s wrqm\/s r\/s w\/s rsec\/s wsec\/s avgrq-sz avgqu-sz await svctm %util sda 0.48 2.76 1.90 0.92 56.44 29.40 30.53 0.01 4.48 2.46 0.69<\/p>\n<p>Work out the queue length requests * average wait time \/ 1000 = queue length ((1.90+0.92) * 4.48) \/ 1000 = [&#8230;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"_links":{"self":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/2658"}],"collection":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2658"}],"version-history":[{"count":1,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/2658\/revisions"}],"predecessor-version":[{"id":2659,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/2658\/revisions\/2659"}],"wp:attachment":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2658"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2658"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2658"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}