One minor correction David... Since OS/390 became z/OS it has not used XSTORE in any way. If you give XSTORE to z/OS it spits out a message at IPL time that it has detected some XSTORE but will not use it.
Mike C. M. (Mike) Hammock Sr. Technical Advisor IBM System Z Solutions Mainline Information Systems (404) 643-3258 [email protected] "David Boyes" <dbo...@sinenomin e.net> To Sent by: The IBM "[email protected]" z/VM Operating <[email protected]> System cc <[email protected] ARK.EDU> Subject Re: XSTORE 03/04/2009 05:06 PM Please respond to The IBM z/VM Operating System <[email protected] ARK.EDU> Paging hierarchy. Think of XSTORE as a really highspeed buffer between main storage and real disk. If you hit a spike in paging activity (like when all your Linux guests wake up near the same time to do something cron-related), you dramatically increase the probability that the pages you want/need are in XSTOR rather than having to wait for them to come in from physical I/O. I don’t really bother to attach XSTORE to a userid unless it’s z/OS or maybe VSE. In most cases I’ve seen, those are the only guest systems that really know what to do with it, and they’re doing so much of their own thing that the impact on the floor system isn’t usually their big issue. On 3/4/09 1:55 PM, "Michael Coffin" <[email protected]> wrote: Hi Folks, What value is there in defining XSTORE these days? Aside from the ability to attach XSTORE to specific virtual machines, wouldn't it be best to just make it all DPA and let CP manage it? Also, assuming you aren't paging much - is attaching XSTORE to a userid going to provide a VERY noticable improvement in performance (at the expense of taking it away from all other virtual machines, of course)? -Mike This e-mail and files transmitted with it are confidential, and are intended solely for the use of the individual or entity to whom this e-mail is addressed. If you are not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you are not one of the named recipient(s) or otherwise have reason to believe that you received this message in error, please immediately notify sender by e-mail, and destroy the original message. Thank You.
