I/O response time of a multi-block reads
From: <maks71_at_gmail.com>
Date: Mon, 31 Mar 2008 14:44:34 -0700 (PDT)
Message-ID: <8d896d1c-5a2c-4bdb-8f6e-5730f1deb199@8g2000hse.googlegroups.com>
Date: Mon, 31 Mar 2008 14:44:34 -0700 (PDT)
Message-ID: <8d896d1c-5a2c-4bdb-8f6e-5730f1deb199@8g2000hse.googlegroups.com>
How to measure the I/O response time of a multi-block reads from SQL
trace file or OWI?
e.g..
nam='direct path read temp' ela= 9291 file number=9999 first dba=28977
block cnt=15
Should elapsed time(ela) be devided by number of blocks (cnt) to derive the i/o response time ( to match w/ iostat service time )? I know "ela" needs to be converted to ms (ela/1000) .. my gut feeling tells me that it should not be as it's being passed to OS as one request but got challenged by few folks..
What should be the typical i/o response time value for such multiblock i/os[ on a standard SAN HDS/IBM/EMC ] ? does <20ms i/o response time standard apply here?
Thanks Received on Mon Mar 31 2008 - 16:44:34 CDT