For dasd cache, all writes are hits unless there is a non-volatile storage full (error) condition.
If you have dedicated dasd addresses for linux guests, the dasd cache report (ESADSD5) shows percent of I/O that is read vs write, and the percent of each that are hits. The seek reports show by user which user is writing/reading where - and shows minidisk read/write percent. However, this does not include reads that are MDC hits as we don't get seek records if the i/o is handled by mdc. If a device is shared, it gets a big tedious to correlate the MDC, dasd cache and seek data with accuracy. >From: Brian_Nielsen<[EMAIL PROTECTED]> > >At the moment I only need to deal with a couple dozen Linux >images and each has different access patterns based on the >application that runs in it. I doubt Linux (SUSE) will have >any of the complicated channel programs that would confuse MDC. > >If I use the assumption of no complicated channel programs, just >straight - forward reads and writes, where would I find info >on (or how would I determine) the relative performance metrics >of cache read/write hits & ; misses? > >I have good stats on the MDC cache hit ratio and read/write >ratio of each guest. If I had reasonable metrics for the >relative performance of cache hits vs. misses for reads >and writes I could take a decent stab at determining which >Linux guests are good candidates for using MDC or not. > >Brian Nielsen > "If you can't measure it, I'm Just NOT interested!"(tm) /************************************************************/ Barton Robinson - CBW Internet: [EMAIL PROTECTED] Velocity Software, Inc Mailing Address: 196-D Castro Street P.O. Box 390640 Mountain View, CA 94041 Mountain View, CA 94039-0640 VM Performance Hotline: 650-964-8867 Fax: 650-964-9012 Web Page: WWW.VELOCITY-SOFTWARE.COM /************************************************************/
