Is it possible to backup a server with just a remote agent on the guest operating system on a Server 2008 R2 host server? If it is possible would there be any major overhead?
I understand Symantec Backup Exec 2010 allows you to backup VHDs directly using the specialized agent for Microsoft Virtual Machines, yet, I need a temporary resolution until our Exchange server is upgraded to 2010/2007 from Exchange 2000
While BackupExec 12.5 also has virtualization agents available, I don't use them. I've been happily using BackupExec 12.5 and 2010 to backup my virtual machines as if they were physical machines for several years now. Install the agent as you would on a physical machine, add the machine to the relevant backup selection list(s) and you should be fine.
I have done backups of VMWare guest operating systems by acting as if they were an non virtualized OS with Netbackup before and it was fine. So I just installed the backup client within the guest OS and backed it up that way. This is not your exact situation but the same in principal.
You might however want to time the backups so both the host and guest are not backed up at the same time if you have any sort of multiplexing going on. (Although if I remember correctly backup exec can't do that, only netbackup?)