Really there are 3 parts to a VMWare cluster that ...

2008-04-16T10:32:00.000-04:00

Really there are 3 parts to a VMWare cluster that apply to this.

VMotion: The ability to move a running VM from one healthy piece of hardware to another healthy piece of hardware.
DRS (Distributed Resource Scheduling): The ability of VI to move a workload dynamically or though manual recommendations utilizing VMotion with the caveats above.
HA (High Availability): The ability to REBOOT a workload on another piece of healthy hardware in the cluster in the event of isolation or failure. This still results an an interruption of business service and momentary (reboot and application start time) loss of availability.

I don't know that either Availability or Capacity is inherently better but without capacity you can impact availability.

I wanted to do a knock off the Dire Strait's tune ...

2008-04-16T10:14:00.000-04:00

I wanted to do a knock off the Dire Strait's tune - Money for Nothing and then change the "I want my MTV" into "I want my Availability" - VKernel will then hire a Dire Straits cover band to perform it somewhere.

Availability vs. Capacity - is one better than the other?

Are there types of Availability?

Virtual John writes about High Availability (HA) vs. Continuous Availability (CA)

"In plain English this means, if one of your hosts in a cluster of VMWare Servers goes away the VMs will reboot elsewhere. Reboot = downtime, so is this high availability? Or just higher availability than no fault tolerance?"

It could be a important misnomer - the VM's with HA will be expected to not have any interruption of business service (enter VMotion) and voila - "I want my Availability".

Rob Bergin
Systems Engineer
www.vkernel.com

Comments on Virtual John: HA = High Availability?

Really there are 3 parts to a VMWare cluster that ...

I wanted to do a knock off the Dire Strait's tune ...