Hi, Eric and Barbara Sammons <[EMAIL PROTECTED]> wrote: > > Looking into performance problems, in search of some ideas of what to > look for. I believe the issue may be related to the type of DASD > being used. > > Scenario, dd command to generate a 1G file if=/dev/zero takes 15s on > x86_64 platform. The same command takes 15m on the s390x platform. > In my environment the command takes 16s. My environment leverages > MOD-3 DASD while the environment in question has MOD-9 and MOD-27 > devices. I know historically the MOD-9 is typically a slower device > but I don't know much about the MOD-27. > > Is it truly possible that the performance of these devices is bad > enough to see such a difference between MOD-3 and x86_64 v. MOD-9 and > MOD-27?
I think the use of different models should not result in such a big performance difference. Today these different models just indicate the different sizes of the DASD volumes as they are defined on a storage server. I would rather look for the difference in the storage servers that these DASDs are defined on. > What else should / can I look at to determine the root cause > of the performance issues? You can get an indication of what is going on in the DASD device driver by looking at the /proc/dasd/statistics interface. A documentation on how to use that interface and how to interpret the data can be found on developer works: http://www.ibm.com/developerworks/linux/linux390/perf/tuning_how_tools_dasd.html You may also want to check /var/log/messages or dmesg for messages that indicate errors or recovery actions. Best Regards / Mit freundlichen Grüßen Stefan Weinhuber -- Linux for zSeries Development & Services, Dept. 3303 IBM Deutschland Entwicklung GmbH Vorsitzender des Aufsichtsrats: Martin Jetter Geschäftsführung: Herbert Kircher Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
