Friday, January 22, 2010

MySQL on VMware Workstation/DRBD vs. VMWare ESX Server/SAN

Or an active-active fail-over cluster à la VMware.

Today I have learned about a totally crazy/cool looking architecture where the expensive VMware ESX server was replace by a free/cheap VMware Workstation version in combination with DRBD.

Basically DRBD we name "the little man's SAN" and that is exactly what this customer is doing. He replaced the SAN with DRBD and now he can easily move one VMware instance to the other host. Possibly it is not that flexible and powerful as an ESX Server but also not so expensive...

The architecture looks as follows:


According to this customer it works stable on about a dozed of installations and they have not experienced any troubles during the fail-overs.

Please let me know your experience, thoughts or concerns with this architecture...

PS: When you consider such an architecture do not expect a very good performance!

2 comments:

Charlie said...

You should expect stellar performance, actually! DRBD, when configured well, has less than a 10% overhead.

When scaling to > 2 nodes, it's probably recommended to use iSCSI. A pair of redundant iSCSI serveres (replicating with DRBD, of course) can serve 10+ VMware hosts if they have a few bonded gigabit NICs.

Oliver said...

I have set up almost identical scenarios on top of Xen, and I found performance to be quite acceptable.

I've also implemented the same thing with Oracle 10g XE (which was a little adventure trying to "staple on" HA to a product that does not support it in any way, and is as horribly installed as Oracle), and with Microsoft SQL Server running within Windows 2008 servers which were also VMs on Xen with DRBD as the backing storage.

Windows is a special case though as it is hard to get 2008 working on Xen with good PV drivers. Nonetheless, anything is possible.