Re: Need help preparing a presentation explaining how zVM manages storage....zVM 5.2
On Sat, Mar 1, 2008 at 9:55 PM, Hamilton, Brian <[EMAIL PROTECTED]> wrote: > - you only have 8gb of central and 512mb of expanded storage > however you have 6 linux instances running each defined at 2gb…how is VM > managing that, especially when you only have 8gb of central? > > - how and when does the 512mb of expanded storage come into play? > > - how and when does the paging volumes come into play? > > - big question how many more linux instances can be built at 2gb > each? John is very right that you should not define additional guests now. I would say you need to go back and define paging space. The only reason you have no problems now is because the Linux guests are so big they have not seen data yet to use the memory you gave them. Once they do (and eventually they will) then you will find 16 GB does not fit in 8 GB. And since you have not even enough paging space, your system will abend in the near future. I compare this with a bucket of water on the table. You can push it pretty far, until at one point very suddenly it falls over the edge. When the system pages (and you eventually must, to make things cost effective) you must be prepared to have enough paging space to hold all virtual memory you promise to your Linux guests. And for performance reasons you want paging space used at most 50%. So each new 2G server requires 2 more 3390-3 page packs. Simple math. Proper sizing and tuning is needed to make it work well. You need a performance monitor to tell whether you've done it right. Rob -- Rob van der Heij Velocity Software, Inc http://velocitysoftware.com/
Re: Need help preparing a presentation explaining how zVM manages storage....zVM 5.2
Brian, I suggest you don't define another 2gb Linux guest else VM might run out of page slots and then crash. Ignoring performance issues, your 2 mod3's of 4.6gb of pages + 8gb C + 0.5gb X = 13.1gb and another 2gb Linux guest (14gb of Linux pages) will force CP to page the excess to your spool dasd which might not have enough free slots, in which case VM crashes. This e-mail, including any attachments, may be confidential, privileged or otherwise legally protected. It is intended only for the addressee. If you received this e-mail in error or from someone who was not authorized to send it to you, do not disseminate, copy or otherwise use this e-mail or its attachments. Please notify the sender immediately by reply e-mail and delete the e-mail from your system. -Original Message- From: The IBM z/VM Operating System on behalf of Hamilton, Brian Sent: Sat 3/1/2008 3:55 PM To: IBMVM@LISTSERV.UARK.EDU Subject: Need help preparing a presentation explaining how zVM manages storage....zVM 5.2 Trying to put together a high level presentation explaining how VM manages its storage. The presentation is being given to our user community. Some background info, 1 VM lpar defined with approx. 8gb of central storage and 512mb of expanded storage, 1 IFL processor. 2 full 3390 mod3's have been defined for paging. 6 linux instances running all of which are defined at 2gb. As of today there are no performance issues (knock on wood). Some of the questions being asked thus the reason for the presentation, - you only have 8gb of central and 512mb of expanded storage however you have 6 linux instances running each defined at 2gb...how is VM managing that, especially when you only have 8gb of central? - how and when does the 512mb of expanded storage come into play? - how and when does the paging volumes come into play? - big question how many more linux instances can be built at 2gb each? Thanks
Need help preparing a presentation explaining how zVM manages storage....zVM 5.2
Trying to put together a high level presentation explaining how VM manages its storage. The presentation is being given to our user community. Some background info, 1 VM lpar defined with approx. 8gb of central storage and 512mb of expanded storage, 1 IFL processor. 2 full 3390 mod3's have been defined for paging. 6 linux instances running all of which are defined at 2gb. As of today there are no performance issues (knock on wood). Some of the questions being asked thus the reason for the presentation, - you only have 8gb of central and 512mb of expanded storage however you have 6 linux instances running each defined at 2gb...how is VM managing that, especially when you only have 8gb of central? - how and when does the 512mb of expanded storage come into play? - how and when does the paging volumes come into play? - big question how many more linux instances can be built at 2gb each? Thanks
