Understanding Synthetic Backups

[PaulStevens]

Understanding Synthetic Backups

I am looking at implementing synthetic backups to reduce backup time/impact to the client. I am totally new to synthetic backups.

Background:

Netbackup 6.5.6

Disk based storage unit (BasicDisk)

Media Manager storage unit with LTO4 tape drives.

We have contractual obligation to store full backups on tape at offsite location.

The data is Filenet data, in 32GB MSAR files so dedup would not help us for this particular app.

My plan:

disk based backups, initial full backup and daily incrementals.

on a weekly basis, run a synthetic full to create the offsite copy.

My questions:

How long do I set the retention for my initial full and daily incrementals?

Should I be doing incrementals, or do I need to use cumulative incrementals?

Do I ever need to rerun the regular full backup?

[mph999 · Accepted solution]

The incrementals need to be kept long enough to be available for the synth full, just as an example if you ran the synth full every week, I would probably keep the incr, at least 10 days , just invade of failure, and a rerun being required. In theory, you never run a real full, after there very first one. Martin

[Mark_Solutions]

You may have one issue here depending on if i have interpreted you question correctly....

"Real" Full backup to disk

Incremental backups to disk

Synthetic Full to tape? <- This needs to go to disk as well as it becomes the new Full that future Synthetic backups will use - if done to tape and the tapes have gone off site you wont be able to do the next Synthetic.

So do all backups (real full, incremental and synthetic full) to disk and duplicate these to tape.

Ensure that you have enough disk space to hold all of these as if a full expires off disk (staged or capacity managed) you will not be able to do the next Synthetic without bringing the tapes back.

I also remember a note going around reccomending that a "Real" full backup be performed once every month - just to be on the safe side!

Hope this helps