|Lee Marzke on 21 Sep 2010 21:51:32 -0700|
On 09/21/2010 08:00 PM, Casey Bralla wrote:
On Tuesday 21 September 2010 7:25:26 pm Lee Marzke wrote:On 09/21/2010 06:04 PM, Casey Bralla wrote:I've got a weird problem which I hope somebody here can help me figure out. I'm running about a dozen virtual machines (mostly web servers) on a triple- core AMD system running Debian Lenny (ie: "Stable"). Each of the virtual machines is also running Debian Lenny. I am having repeated disk errors on the Virtual Machines, but no disk errors on the host machine. These disk errors often cause a Kernel Panic within the VM, or otherwise crash the web server on the VM.What are the specs on the host, memory, number/type of disks, vmware server version amount of RAM allocated to VM's and amount left over for the host.Host Specs: AMD Phenom Triple Core 2.4 GHz ASRock Motherboad with AMD RS870L chipset 4 GBytes G.Skill RAM (2 DIMMS) Debian Lenny VMware Server 2.0.2 Build 203138 free reports: total used free shared buffers cached Mem: 3935036 3902036 33000 0 154324 2704932 -/+ buffers/cache: 1042780 2892256 Swap: 11807732 748 11806984 df -h reports: Filesystem Size Used Avail Use% Mounted on /dev/sda1 576G 184G 363G 34% / tmpfs 1.9G 0 1.9G 0% /lib/init/rw udev 10M 748K 9.3M 8% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm Most VM's given 64 MBytes RAM and 3 GByte SATA disks (which are fully allocated when they are created) Here's a mem and free from within a "typical" VM: total used free shared buffers cached Mem: 61480 58980 2500 0 26456 12560 -/+ buffers/cache: 19964 41516 Swap: 176672 540 176132 Filesystem Size Used Avail Use% Mounted on /dev/sda1 2.8G 676M 2.0G 25% / tmpfs 31M 0 31M 0% /lib/init/rw udev 10M 600K 9.5M 6% /dev tmpfs 31M 0 31M 0% /dev/shm
64Mb per VM ? That seems way, way too low. The Debian recommendation is 256Mb + what is needed by apache.
Is there some reason you have a dozen VM's ? Shouldn't apache handle hundreds of websites on a single VM ?
Can I assume you have thousands of websites then ?If you really have that many VM's you may need to re-think your architecture somewhat. I don't think a single disk system with 4GB of RAM is going to run a dozen VM's, that system is barely good for 4 servers servers. CPU usually doesn't matter, it's usually memory and then disk I/O that are the issue. Here I have a dual socket dual-core Opteron 265 SuperMicro MB, with 12GB RAM, running ESXi 4.0
A single disk drive spindle just isn't going to do very well. Your OS should be on one disk or flash drive and the VM's on an array. You may want to use OpenFiler ( which is VMware certified ) with a half-dozen or more disks mounted to your host over NFS. And put the NFS traffic on a different NICS and separate LAN. I use a Thecus N8800 NAS here.
If this is production and you wish to stay with VMware, then you really need to use ESXi instead of VM server. ESXi is 64 bit, and allows you to add memory above 4Gb. With that many VM's at 512Mb each plus overhead that's about 8GB memory required. Most ESX blades in data centers I've seen have 64GB or more RAM each.
ESX has a 60 day free trail, so you can evaluate this pretty easily without cost if your server will boot ESX. The
Vmware converter will migrate the VM's you have easily into ESX.I just gave a talk Monday at VMware user group on moving to ESXi , that you might find interesting. http://plone.4aero.com/Members/lmarzke/vmug_esxi/moving-to-esxi-introduction/presentation_view
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