Was asked this morning to investigate the Pro's/Con's of Virtualisation of our Network to try and consolidate as many of our existing servers into Virtual Servers..
What servers have hardware Virtualisation support?
what Spec should I look at?
The other poser is what roles are suitable for virtualising?
DC, WDS, WSUS, SQL, File-Servers, etc, etc..
Almost all new servers contain virtualisation support thanks to the latest revision of CPUs. New core2 based Xeons and current Opterons have built it support.
Originally Posted by Gatt
As to spec, lots of ram 8GB, a couple of quad core CPUs and some quick storage will do quite well for 6 or so vservers depending on loading requirements.
You may want two of these rigs for redundancy as if your one virtual server blows something it will take out your whole system.
A SAN is the best as you can have both VM servers storing their images on the SAN but short of that a reasonable RAID controller with a stack of cache (512mb) would be a good idea.
You can virtualise any of the roles that you suggest above, if you go for the SAN option it may be faster to host files directly off that.
Cheers for that..
was thinking of about 16GB ram? and prob a Tb of disk space but will look into the SAN option too
Will need to get prices too - probably gonna be some form of HP ProLiant
One thing to remember is that consolidation only works with your *unused* capacity. There are additional benefits depending on what software you use though. Template machines, imaging etc. If you don't have enough servers to keep up then it doesn't get you very far - first thing is to check cpu/ram stats for current servers before planning.
Working backwards, you can virtualise anything although if it uses special hardware you are likely to have problems.
functions like DC, DHCP, WSUS are very light in terms of CPU, RAM, HDD so can go as a virtual server in a "spare corner".
One of the real benefits of virtualisation is ease of backup. We're only using MS Virtual Server but I'm pretty sure VMWare has similar facilities. What we do is to pause the server in the middle of the night, copy the virtual disc and config files to another server and then resume it. Should the host system fail, it's a job of a few minutes to bring up the guest OS on another machine.
With ESX you can create a redo log that leave the machine running but locks the disk file for backup without pausing/powering off. A crash consistent state - fine for most things, not so good for databases.
Originally Posted by srochford
Yeap, the ram is all dependent on your servers requirements, ie exchange2k7 4gb + File 1-2GB + DC 1GB etc. likewise with the HD space. The big thing is the HD throughput as the HDs are usually a bottleneck when just used by a single system, VMs each make the same demand on the HDs speed.
Originally Posted by Gatt
We got recommended an hp DL380 by one of our suppliers for a VM server starter. They are really nice units, we've got one with a couple of quad cores in it + 512MB raid controller and it is very fast at what we have tasked it with. In our case its not VMs though so I can't elaborate on its VMing speed from personal experience.