On 5/31/07, Tracy R Reed <[EMAIL PROTECTED]> wrote:
rbw wrote: > So the increase in RAM would be a bigger factor that the increase to 2 > virtual CPU's and the lower overhead of XEN? Definitely. RAM is always the first thing you should look at when a machine needs to be faster because when a machine gets "bogged down" you are almost always waiting on the machine to swap.
If you're virtualizing, and the host server is swapping, you're really asking for big troubles. All of my experience is with VMware, and I've had a test system roll over and die once it had about 10 VMs running and the host server was configged with 2GB of RAM. Not only did the host lock up, it trashed nearly every virtual disk for all the machines. Luckily, I was just messing around with VMware server, so no actual harm done. Virtualization makes great use of hardware, but the impact of running so many VMs is that there are more systems that can be effected when the host has issues. Memory is my biggest issue, disk space is next, I've not run into any issues with disk or network I/O. So far, running 7 VMs under VMware ESX has been nearly flawless in operation for over a year. Much like people use RedHat for highly mission critical stuff that require support, and CentOS of other not so mission critical, VMware can be done the same way. I use ESX on production servers which get nightly mirrored over to a second server, then VMware server for all my dev and testing. If you want hot failover of VMs, you can use VMotion. One host fails, VMotion detects that, and restarts the VMs on other hosts as needed. None of this requires a SAN like the older days, but it can be done over NFS. Pretty cool stuff actually, XEN or VMware. VMware itself is a customized version of RH7, IIRC.... -- Mark Schoonover, CMDBA [EMAIL PROTECTED] Cell: 619-368-0099 * software development * systems/database administration * networking * security * -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
