Yes, and the original statement was based on the assumption that the over commitment of real memory was high. Obviously if there is little to no over commitment than you will see very little paging from z/VM on behalf of the users.
I will also add that even in z/OS say you are running a good size DB2 environment if you do not have ample real storage you will still see paging for sure to your paging subsystem and without expanded storage no longer available in z/OS it will go right to DASD. Thank You, Terry Martin Lockheed Martin - Citic z/OS and z/VM Performance Tuning and Operating Systems Support Office - 443 348-2102 Cell - 443 632-4191 -----Original Message----- From: The IBM z/VM Operating System [mailto:[email protected]] On Behalf Of Mark Post Sent: Friday, September 17, 2010 10:53 AM To: [email protected] Subject: Re: CP unresponsive on certain guests >>> On 9/17/2010 at 09:24 AM, George Henke/NYLIC <[email protected]> wrote: > Does z/VM, unlike z/OS, still need to do a lot of paging? > > In the z/OS world paging has become virtually(no pun intended :-)) > non-existent. z/VM does very little paging (if not zero) on behalf of itself. Because z/VM allows considerable overcommit of storage among the various guests, it can wind up doing a _lot_ of paging to manage all that. If you ever started using z/OS as a hypervisor, it would have the same problem, unless you strictly limited the amount of virtual storage each guest had to add up to less than the available real storage. Mark Post
