From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Kirstein Subject: Maximum number of DomUs? (x86_64) Date: Sun, 9 Apr 2006 03:37:26 +0200 Message-ID: <20060409033726.A9073@web.ray.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org Hallo, I just tried to push a quad-opteron server with 16GB of memory to the limit and I reached it a bit earlier than expected. It seems that no matter how much memory I assign to each DomU, and wether i use loopback or phy/lvm devices for the storage, or no vif/storage at all, I can't crate more than 107 DomUs (yes, that's not a real problem, I'm just curious :) After No. 107 that I get(*): Using config file "vm107". Started domain VM107 Using config file "vm108". Error: (12, 'Cannot allocate memory') Using config file "vm109". Error: (12, 'Cannot allocate memory') but of course there's still memory left in Domain-0 to balloon out: Name ID Mem(MiB) VCPUs State Time(s) Domain-0 0 9215 4 r----- 319.3 VM1 1 64 1 ------ 0.8 VM10 10 64 1 -b---- 0.7 VM100 100 64 1 -b---- 0.4 When I assign 128MB per DomU exactly the same effect: Name ID Mem(MiB) VCPUs State Time(s) Domain-0 0 2372 4 r----- 2196.3 VM1 129 128 1 -b---- 0.4 VM10 138 128 1 -b---- 0.4 VM100 228 128 1 -b---- 0.2 So I wonder, which structure could run out of memory there? Is this a known limitation? Didn't find much about the maximum number of DomUs in the list archives... The Dom0 is running a CentOS4 x86_64 and I don't even need a DomU image to reach this limit, network and diskless DomUs just running into an "no root filesystem" panic being "preserve"d after the crash have the same effect. (:ul8er, r@y (*) yes, I know, I could have used a vmid parameter instead of creating 100s of configfiles :)