snapshot size is difference between oncommand and netbackup

[YOKOMATSUMOTO]

Dear All,

I have a plan to create backup by SMVI and Netbackup.

The target volume is connected to ESX by iSCSI as a datastore, so I made a snapshot via SMVI.

My quiestion is , Oncommand System manager shows that snapshot size  is 4.83GB

but on Netbackup much bigger size was written into tape.

It's big difference, which is correct and how can I estimate for backup of all virtual machines??

oncommand : 4.83GB

netbackup kilobytes written  :   34040833(=roughly 32GB)

[aborzenkov]

From NetApp point of view, snapshot size is the amount of unique data, not shared with other snapshots or active file system. But logically every snapshot represents full filesystem image. Depending on how your NetBackup is setup, it may perform full copy, which explains size of tape backup.