When turning dataspace support off in DB2, you may want to turn minidisk caching on for the DB2 minidisks. This is how my customer worked for a very long time, until VM changed the MDC algorithms to become fulltrack caching.
But: the default for minidisks is fulltrack chaching, and that kills D2's performance. The good news is that the MINIOPT statement allows to request record-based minidisk caching. Summary: when not using dataspaces for DB2: - be sure to add a MINIOPT RECORDMDC to each MDISK record of your DB2 server - otherwise DB2 IO all become fulltrack reads there is also a CP SET MDCACHE command to control this behaviour dynamically. Kris, IBM Belgium, VM customer support VM/ESA and z/VM Discussions <[email protected]> wrote on 2006-01-31 16:02:52: > Hi Ed, it does not matter what release of DB2/VM. It is the > dataspaces support in z/VM 5.20 seems to cause this problem. I know > of, DB2/VSE&VM Support is working closely with VM development trying > to identify/resolve this problem. They are advising user to > temporary take the DB2/VM database off from dataspaces support. Yes, > it is a toss up between performance and database corruption! *SIGH* > > I hope this help. > > Regards, > > ...Roland > > Ed Zell <[EMAIL PROTECTED]> wrote: > >> Hi all, Please be adviced that you shouold do more frequent > >> archive of your DB2/VM database if you are using dataspace > >> support and is running under z/VM 5.20. > > > I don't know if this is related, but we just got bit with DB2 server > > hard down. We installed z/VM 5.2.0 on a 2084 this weekend and DB2 > > came up OK at 6am Sunday and ran until 11pm. > > I was curious what version of DB2 for VM this was, or does > that even matter if the problem is with VM dataspaces? > > This reminds me of a MAP MDISK problem with VM/ESA 1.2 that we > ran into back in 1993 on SQL/DS 3.3.0. We had to turn off > dataspace support for several months until it was resolved. > Not a pleasant experience at all. > > Ed Zell > (309) 674-8255 x-107 > [EMAIL PROTECTED] > > . > > CONFIDENTIAL NOTICE: This communication, including any attachments, > is intended only for the use of the individual or entity to which it > is addressed and contains information which may be confidential. If > you are not the intended recipient, any distribution or copying of > this communication is strictly prohibited. If you have received this > communication in error, notify the sender immediately, delete the > communication and destroy all copies. Thank you for your compliance. > > With best regards, > > ...Roland Chung > Senior Technical Specialist (S/390,VM/VSE,DB2/VSE&VM) > MAXC Consultants Inc. > Voice/Fax: 416-469-3280 (If busy, call: 416-469-2268) > 197 Hastings Ave., Toronto, Ontario, Canada. M4L 2L6 > > ** Life is short. Stop once in a while and smell the roses. **
