Virtualization Roundoff

Virtualization roundoff. Pros and cons of VirtualIron. Pros and cons of VMWare server. Pros and cons of XenSource Express.

When it comes to server virtualization there are several options. However small businesses not only need server consolidation but the ability to run multiple operating systems with best server utilization.

So which product meets the needs of a small business? It really depends on the needs but for Aquevix, here's what I concluded. Note that this is not a performance comparison. It is what is practical for a small business.

Products evaluated:

1. VMWare Server 1.x
2. XenSource Express 4.x
3. VirtualIron 4
4. OpenVZ
5. Oracle VM
6. CentOS 5 with native Xen Support
7. Suse Linux with native Xen Support

(are there any more ??)

The Setup:

Dell PowerEdge 830 with Pentium 4 Dual 3 GHz, two 160 GB Sata HDD configured as Raid 1, 2 GB RAM.

Base OS: CentOS 5.0 x86 with all patches installed. On this machine, HDD gives approximately 70MB/sec throughput. (hdparm -tT /dev/md2)

VMWare server

Pros:

1. Easiest to install and use
2. Work best with obscure OS's
3. Can install on a machine with other software. So I can have applications that use CentOS install natively and remaining as Virtual Appliances.

Cons:

1. Slow. Average Guest VM with a SATA drive, performance measured approx 12-18 MB/sec.
2. Advanced HDD options to use a partition did not work. Partition got corrupted after install.

Note: Currently using with tears in my eyes.

XenSource Express

Pros:

1. Very easy install and configuration.
2. Works fast. Guest VM Hard Drive performance approximately 48 MB/sec. Need to install PV drivers to boost the HDD speed.
3. Free for 4 concurrent machines running. Can have any number of machines in off state.
4. Excellent for virtual containers with CentOS 4/5 and other supported platforms.
5. LVM support for easily resizable virtual hard disks or EXT3 partitions for sparse file support.

Cons:

1. Only 4 concurrent clients in free version.
2. Needs a complete server to install.
3. No support for Software Raid. Need to touch command line for creating a Raid-5.
4. Doesn't works with some OS's. For example Win98 didn't work for me.

Note: Currently using with Software Raid-5 (3 disks).

VirtualIron

Pros:

1. Seems interesting. Based on Xen.
2. 12 virtual machines concurrent in free version.

Cons:

1. Cannot get any VM to install and work.
2. Very poor performance possibly due to Java.
3. The virtual console is very poor.
4. Complicated, non-intuitive interface.

Didn't work well for us.

12 virtual machines concurrent in free version! I couldn't get even one to work.

OpenVZ

Pros:

1. Good technology. Very thin virtualization layer.
2. Technically HDD speed is same as normal server speed, 70MB/sec on Raid-1.
3. Could get most things working.

Cons:

1. Need to mess with host kernel. Can easily break other applications.
2. Pain to setup.
3. Windows etc. won't work. Best for thin virtualization of same OS instances.

With modified kernel, VMWare won't work. Gave up after this point.

Oracle VM

With Oracle I always start with Oracle Sucks. I fail to understand why everything oracle is HUGE. Even a simple VM server setup requires a management server and a VM server. Even then the install, configure are very complicated. I gave up after a while. Why bother when there are so many other alternatives available that work great.

CentOS with native Xen Support

Evolving but not mature. Best for para-virtualized CentOS4/5 only.

Biggest problem was that guest machines (except CentOS4/5) didn't shutdown properly (used to poweroff)

Maybe in future.

Suse Linux with native Xen Support

Didn't try. Might work. Problem will be no optimized HDD drivers.

Conclusion:

If you can afford, go with Virtuzzo (OpenVZ paid version) or XenSource. If you cannot afford XenSource Express. Keep VMWare Server around when world seems crashing on you.