Hi, Swapping VM memory to host page file isn’t the same as disabling the page file in the Guest OS. One allows over-committing memory on the host (because some of the RAM used by the guests can be paged to the page file on the host), whereas the other prevents the guest from using a page file inside the guest OS.
Windows Server 2008 Hyper-V does not support over-committing memory. If you allocate 8GB of RAM in total to your guest machines, you must have 8GB of physical available RAM (plus about 50MB/VM for management overhead and VMBus) in the machine. Cheers Ken From: Matthew W. Ross [mailto:[EMAIL PROTECTED] Sent: Wednesday, 14 May 2008 5:05 PM To: NT System Admin Issues Subject: RE: HIJACKED THREAD: Virtual Memory and Virtual Machines (WAS: RE: Why XP is doomed) In my case, I don't have a SAN. Just a decent raid controller, and a bunch of smaller VMs doing single tasks. Also, there are options in VMWare to allow/disallow swapping of memory of the guest OS. I don't know if Microsoft's Server 2008 VM has that setting. --Matt Ross ________________________________ From: Ken Schaefer [mailto:[EMAIL PROTECTED] To: NT System Admin Issues [mailto:[EMAIL PROTECTED] Sent: Tue, 13 May 2008 23:40:33 -0700 Subject: RE: HIJACKED THREAD: Virtual Memory and Virtual Machines (WAS: RE: Why XP is doomed) So, you are talking about: a) Disabling the page file inside VMs (A), (B) and (C) b) Hoping that the OSes inside those machines never need more than 512MB of RAM ? I suppose it’s possible. But do you want to risk it? I’m not sure you’d gain very much. Most people put the VMs on a SAN (for performance as well as HA reasons), so raw IOps shouldn’t be an issue. Cheers Ken From: Matthew W. Ross [mailto:[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>] Sent: Wednesday, 14 May 2008 4:37 PM To: NT System Admin Issues Subject: HIJACKED THREAD: Virtual Memory and Virtual Machines (WAS: RE: Why XP is doomed) Oooh... that brings up some questions... I've always wondered if anybody has looked at Virtual Machines, and the use of Page files... Let me explain. Let's say we have a box with 4 virtual machines. Each virtual machine is given 512 megs of Memory, and is running windows 2003. The host server has 4 gigs of ram, so the 2 gigs being used by the VMs is no problem, and plenty of room to spare. Of the four MVs, you have: A) A DHCP/DNS/WINS server B) An Active Directory server C) An IIS server serving simple static pages D) An SQL Server with a moderately heavy database Could someone take VMs A, B, and C and give them a ZERO page file increasing performance for all parties? This is assuming that the jobs that VMs A, B, and C are all able to run their important but trivial tasks directly from memory, while VM D has less to compete with for IO to the harddrives? Has anybody done this kind of thing with success? Just a thought. It's ripe for the squashing. Sm:)e. --Matt Ross ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~
