Backing up ESX4.0 guest VM's
I have been looking at our backups recently with the intention of improving performance and reducing the amount of time taken. I have noticed that the backups of virtual machines take much longer compared with the backups of physical hosts. As we are moving to a majority VMware server estate and several large servers are scheduled to be migrated, I need to improve this backup performance drastically.
Our current setup is:
ESX and vCenter 4.0
EMC CX3-10 SAN attached by fibre to the ESX hosts
Backup Exec 12.5
The backup server is not attached to the fibre network
VM’s are currently backed up using VCB within Backup Exec 12.5, with the backup server is acting as the proxy
I am using the NBD option.
Backups are to normally LT03 tape
I have run some simple test using both VCB and agent backups to disk backing up 2 different servers.
The agent backup took 1hr 20 min for 108GB @ 1500MB/min
The VCB backup took 9hr 10min for 181.3GB @ 315MB/min
The agent backup took 24min for 9GB @ 359MB/min
The VCB backup took 36min for 10.6GB @ 280MB/min
This is without encryption or validation.
The main questions I have about these results are:
Why is there such a huge difference between agent and vcb backups on server 1? I understand that VCB backups are always larger data and time wise, but this is surly excessive?
Why is there such a difference of throughput between the agent backups for server 1 compared with server 2?
I have been backing these servers up to the same disk that the VCB uses as a proxy, could this have caused the performance issues? Neither of these servers are production, so I don’t have any back up to tape logs to compare them with.
Lastly I have been led to believe that there will be a large performance increase if I use the SAN option with VCB as they will be backed up directly from the LUN. Is this just a case of attaching the backup server to the fibre network? Any possible pitfalls around using this option?
I understand that this i a complex setup with many possible 'issues' but i appriciate any help that i can get.