Backup Central

I'm a storage/backup newbie.

How does off host backup work when backing up a virtual machine (or all VMs on an ESX server?
What takes a snapshot of the disks? Is it some VMWare software on the ESX server, or is it the backup proxy server software? Is the snapshot created on the ESX server's disk and then somehow "transported" to the proxy server?

How does this snapshot process work? Is there special hardware/software in the ESX server that allows it to quiese I/O? Is that VMware software or software from the backup vendor?

Thanks!

Basically the off-host system has to be able to see the same storage as the ESX server, and depending on how you do it, the storage system may need to be intelligent enough to do the snapshots. They all communicate with each other to coordinate the snapshots and then the backup.

In any case, it sounds like you have a lot of research to do.