VM64461 puts the brakes on console spooling by detecting that something crazy is going on and may exhaust all of vm's memory and pauses the virtual machine to allow the writes to disk to take place and the memory to get back under control. I believe messages are put out. My understanding of that may be off a little, but that's the gist of it.
I'd like to see something like that. If a virtual machine is up and running and CP sees that it is grabbing all of the page space at an excessive rate or if it is in danger not getting its page management blocks into memory then stun it (or maybe even a parm that says no one user can use more the x% of page). Put out a message to Operator about "Userid BIGBAD has been halted due to excessive memory consumption" or something like that. Marcy "This message may contain confidential and/or privileged information. If you are not the addressee or authorized to receive this for the addressee, you must not use, copy, disclose, or take any action based on this message or any information herein. If you have received this message in error, please advise the sender immediately by reply e-mail and delete this message. Thank you for your cooperation." -----Original Message----- From: The IBM z/VM Operating System [mailto:ib...@listserv.uark.edu] On Behalf Of Schuh, Richard Sent: Friday, September 18, 2009 1:28 PM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: [IBMVM] VM lockup due to storage typo Does "the current physical storage" refer to main or main + xstore? Also, is there any consideration of the total virtual storage or working sets of the in-Queue, in-memory, or logged-on users in the calculation? I wouldn't want a dozen users of 991G each logging on to my system that has only 1.02TB total page+physical memory. It might be better to have a config file maximum and simply measure VM size against it - a MAXSTORE directory option that has been generalized, so to speak. Of course, any MAXSTORE directory entry that is lower would be respected. SET commands could temporarily lift or lower the limit for the system or for specific users. Regards, Richard Schuh > -----Original Message----- > From: The IBM z/VM Operating System > [mailto:ib...@listserv.uark.edu] On Behalf Of David Boyes > Sent: Friday, September 18, 2009 10:49 AM > To: IBMVM@LISTSERV.UARK.EDU > Subject: Re: VM lockup due to storage typo > > On 9/18/09 11:38 AM, "Bill Holder" <hold...@us.ibm.com> wrote: > > > On Fri, 18 Sep 2009 10:11:58 -0400, David Boyes > > <dbo...@sinenomine.net> w > > rote: > >> I think we're all in violent agreement on that point. Now, the > >> question > > is > >> what is the best way to put a safety on that gun? > > Is this a procedural or technical implementation question (or both)? > > For the former, I'd say a requirement is appropriate. > > OK, got that covered and done. > > > For the latter, > > let's have at it. :) > > As I suggested in the requirement: > > Possible solution would be to provide a SYSTEM CONFIG option > (Check_Resource_Alloc_Sanity for discussion purposes) and > associated SET command to check LOGIN, DEF STOR, and IPL > events to determine whether the requested resources (default > virtual storage size for LOGIN, new value for virtual storage > for DEF STOR, and current virtual storage size at time of > issue for IPL) are greater than the current physical storage > and defined paging space. If check is true, then issue a > warning message and cancel the action. > > Option defaults to ON, can be turned off by class A user SET command. > > Not perfect, but would catch most of the scenarios that have > been discussed so far. >
