At TechEd IT Forum a session about "Virtualization and High Availability" presented by Bryon Surace and Mike Sterling, gave some figures on the time it takes for Virtual Machines to failover from one to another host. | VM Memory | 1 GbE iSCSI | 2 Gb FC | 4 Gb FC | | 512 MB | ~8 seconds | ~ 4 seconds | ~2 seconds | | 1 GB | ~16 seconds | ~8 second | ~ 4 seconds | | 2 GB | ~32 seconds | ~16 seconds | ~8 seconds | | 4 GB | ~64 seconds | ~32 seconds | ~16 seconds | | 8 GB | ~2 minutes | ~64 seconds | ~32 seconds |
Keep in mind though that because you are using clustering, when you migrate a single Virtual Machine using Quick Migration, you have to make the Virtual Harddisk of that Virtual Machine available to the other node within the cluster. This means that within the cluster the Shared hard disk needs to fail-over to the other node. This means that all Virtual Hard disks on that shared disk will start to Quick Migrate too.
During the session we were pointed to 3rd party solutions which can solve this problems. They also mentioned to use a disk per Virtual Harddisk and use mount points to make the VHD's available. |
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Virtualization 
