We are using the AVVI client to back up a VSphere 5 environment, as well as a number physical Windows servers.
I set up the system to perform daily incremental backups and monthly full backups, as this allows for 1 to 2 month retention period on our system direct from disk storage, and this disk storage is replicated to a tape library so that tapes can be taken off-site.
This has worked very well.
However, I think that I've read that Symantec recommend weekly full backups, at least with the AVVI client.
Can I please ask, is this so? If a weekly full rather than monthly full is recommended, what is the impact to us of performing monthly backups instead?
Should I really consider changing?
If we do change, then this will have a big effect on our disk storage retention - it'll go down to one to two weeks. Is dedupe the way around that?
The longer the period between full backups, the backup chain (full + incr backups) will be longer and the restore time will increase. If you do your full backup on the 1st of the month and need to restore something on the 30th of the month, you would need to restore the full backup + 28 incr. backups. This is a lot. Furthermore, if any of the incr is damaged, the subsequent backups are useless.
Doing more frequent full backups will reduce these risks.
Thanks Imosla, the document does indeed tell me that weekly backups are recommended.
Thanks pkh, it's really the response that I expected - more risk relying on more incrementals, and the time taken for restores.
I assume that if we're willing to accept the risk of having damaged incrementals, then we still will be fully supported from Symantec, even though not following their recommendation?
It would still be supported, however just because we support it does not mean we can help you recover if something has corrupted the chain of incremental backups since the full. We could prove to you which incremental set is broken but the support would then stop.
Also please be aware (as we had a customer misunderstand this in the past):
A VMware incremental backup set is useless if a previous incremental or the full is corrupt, this is because the backup is a block level operation against changed blocks in the VMDK and not a file level operation against the files that are changing inside the file system of the VM itself. As such you cannot restore just the changed blocks without the rest of the data. (For GRT we mount all the sets in the incremental chain and then recover the files from within that mount, so GRT will not work with a corrupt or missing part of the chain either)
A traditional Agent for Windows backup however is a file level operation meaning that you can still get individual files back from an incremental backup set if the previous incremental or full is corrupt missing.