Hal, Is that always true?
If your application is getting 100% cache hits with 0.3ms response time, has a sub second service level, but issues 10,000 IO then there is no way you will meet your service level even though your response time is as near to perfect as it can be. The number of IO you can do can be as big a problem as the time the IO takes. Looking for some IO avoidance before handing over dollars for more cache, faster drives and SSD can will often result in improved Service Levels, while response stays the same, or even gets worse. It's all about reducing the net IO Time. For example a three level indexed KSDS can easily realize a 350-390% reduction in IO just by changing it to BLSR or SMB and using deferred writes. With that sort of saving would a DASD response time is 0.5ms or 10ms be important? Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of > Hal Merritt > Sent: Wednesday, July 21, 2010 10:32 AM > To: IBM-MAIN@bama.ua.edu > Subject: Re: [IBM-MAIN] Any ROT for DASD Response time > > Point is that you are not meeting your SLA goals. If DASD response time is an > issue, then it can be described as 'poor DASD performance'. It does not really > matter what the response times are, the issue is that they are too slow. > > In this context a ROT for any delay would be zero, IMHO. > > HTH and good luck. > > > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of > Lizette Koehler > Sent: Wednesday, July 21, 2010 11:39 AM > To: IBM-MAIN@bama.ua.edu > Subject: Any ROT for DASD Response time > > We are running an EMC DMX4500 shared with the open system side. MVS has 9TB > and the open side has 500TB. So they win. > > We have points in time where our production application (DB2 Stored Procedures > with Native SQL) has slow responses. > > The DBAs are using RMF and TMON (DB2 and MVS) to isolate the problem. > However, they see DFHSM and say thats the problem. > > I think I am seeing delays on the dasd the DB2 system uses in RMF. But I am > not sure how to interpret the numbers. > > Is there a ROT that says if the delay rate is > ? then the dasd is poor > performaing? > > Thanks > > Lizette > > > NOTICE: This electronic mail message and any files transmitted with it are > intended > exclusively for the individual or entity to which it is addressed. The > message, > together with any attachment, may contain confidential and/or privileged > information. > Any unauthorized review, use, printing, saving, copying, disclosure or > distribution > is strictly prohibited. If you have received this message in error, please > immediately advise the sender by reply email and delete all copies. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
