document updated 13 years ago, on Feb 18, 2011
The "Google approach" to HA (high availability) is to avoid using high-end hardware (which costs a lot), and instead use low-end hardware combined with high-end software[1][2] to achieve the same thing (for a lot less money).
(here, "low-end hardware" means commodity hardware, while "high-end hardware" means specialized server hardware that's internally redundant)
So, what sort of software is available to do this?
- VMware has a variety of packages / features that enable downtime on the order of milliseconds to seconds:
- VMotion — transferring virtual machines between servers on the fly, with zero downtime
- Requires shared storage. Options supported are: Fibre Channel SAN, NAS and iSCSI SAN.
- SVMotion — transferring virtual machines between Shared Storage LUNs on the fly, with zero downtime
- HA — restarting of Virtual Machine Guests in the event of a physical ESX Host failure
- on the other hand, high-end VMware software is ~$3000, yikes