Virtual Server Solution and OS

[Jonathan Mason]

Victor Mendonça wrote:
> Greetings!
>
> I will be implementing a virtual sever solution at work and I'm trying 
> to get as many facts as possible for the best setup.
>
> We want to setup a server at our support department to host a minimum 
> of 8x Windows machines running simultaneously (ranging from XP up, 
> including server, 32 and 64-bit). Some of these machines might run 
> MSSQL which will increase the overhead, however they will be used for 
> testing and bug replication only, so there is no need for them to be 
> lightning fast.
>
> The department could grow and the number of virtual machines might 
> increase in the future (let's say 3x additional machines).
>
> There's also a need for backup, user management and remote management. 
> Costs need to be kept as low as possible, while still providing a good 
> and acceptable performance. Also, the company does not have a formal 
> Linux guy, so they might need to outsource support if I ever leave the 
> company.
>
> I've been doing some research on the following OS's and Virtual Server 
> solutions, including cost, support, usability and other aspects:
>
>
> => OS
> -CentOS
> -Ubuntu
> -Suse
> -Open Suse
> -Open Solaris
>
> => Virtual Severs
> -Vmware Server
> -Vmware ESXi
> -VirtualBox
> -Xen
> -KVM
>
>
> My choices are going for VMware ESXi and either CentOS or OpenSuse 
> (even thou I'm an Ubuntu guy).
>
> Any ideas and/or comments are very welcome!
>
> -- 
>
> Victor Mendonça
> http://wazem.org
>
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>
If you're going with VMware ESXi then you won't be needing a host OS. 
 From what I understand ESX is a bare-metal solution, it IS the host OS.

When I was doing some sysadmin stuff for a small software company I 
tried migrating their VM server from Win2K3 with VMware server to CentOS 
+ VMware server but unfortunately the switch over didn't work, there 
were huge problems with very slow IO. I would probably recommend ESXi, 
since it was designed from the ground up for virtualization I would 
think it is the best performance wise. Also third-party support is 
probably going to be easiest with VMware. The problem with VMware ESX is 
probably going to be hardware though, when I was looking into 
virtualization with VMware ESX their HCL was quite narrow and didn't 
provide support for any SATA controllers, the only options were SCSI and 
iSCSI.

To provide a bit of background the VM server I was trying to transition 
was running 4 - 7 Win2K3 VMs, 2 CentOS VMs and 1 or 2 XP VMs on a dual 
opteron dual-core machine (4x 1.83GHz), 8GB ECC DDR2 with a HighPoint 
RocketRAID controller set-up in a raid-5 array. These VMs were 
configured as build servers and test environments along with the main MS 
SQL 2005 server for the company. There would be at least 6 VMs running 
at all times and then additional VMs would be started on demand. I 
hypothesized that the scalability problem we had was with fragmentation 
with the original VMs being created as single-files which would grow as 
required on ext3. If you go with a linux host OS I would recommend going 
with ext4 if possible because the bottleneck in any VM server is 
probably going to be IO. Preallocation of the file systems would 
probably improve performance.

I've been using VirtualBox for the past couple years on my laptop to 
virtualize Windows XP for my university work, it is also a great tool 
but I don't know how well it might scale for a server configuration. 
When I was running 3 or 4 VMs I was quickly exhausting my 2GB of ram and 
even with VT-enabled the performance on my Core2Duo T7200 was quite 
slow. I would definitely recommend it as a good alternative to VMware 
workstation but I would recommend a lot of testing before trying to roll 
it out in a server.

Jonathan