This looks simple from the start. Install a Symantec Backup Exec 11d media server, a Remote Agent for Linux and Unix Servers (RALUS) inside the ESX server. Run a backup job and it is done!
And then some.
It appears that the agent only allows you to backup closed files. Open files are not backed up. And on the ESX, open files are everything! More on this later.
The ESX server has a Linux portion that is compatible with Redhat. Though some might dispute that. The Linux portion allows you to install Redhat compatible stuff for the ESX eg management agent, Symantec’s RALUS 11d etc.
It also comes with a firewall that denies all traffic incoming and outgoing. Therefore after installing the RALUS 11d, you will need to open a few ports.
Incoming 6101 for Backup Exec browser service or the server will not show up under My Favourites. Add incoming 10000 for the media server to talk to the agent to have the individual folders listed. Outgoing ports, for the agent to talk to the media server. I used 8192 to 8198. Some people put in more.
Now for the open files. As long as the guest is running, vmdk files are opened. The only way is to take a hot backup, is to take a snapshot and backup the snapshot. This could potentially have an overhead of 50% disk space if you snapshot all the guest at one time. Alternatively, you could snapshot each guest, backup, purge, snapshot the next and so on.
I have found that snapshot a guest could take anywhere from 30 minutes to 90 minutes. This does not do wonders for your backup window.