backup rotations - advice required

[jjohnsoncantell]

Greetings,

 

We currently run a backup rotation of 1 monthly full backup, monday to thursday incremental and friday differential via archive bit. Does this work as a strategy?

 

One of the problems we have is the daily incremental for certain folder doesnt seem to be backing up files that are changed on that day but everything in that particular folder. Is this because we are using archive bit instead of modified time seeming as everything in said folder is replaced daily but since its being copied and replaced by a batch file daily the modified time doesnt change?

 

That wouldnt explain however why the weekly differential backup which is usually smaller than the daily incrementals?

 

Any advice welcome.

James

[DT2]

Previously I have dealt with a similar issue. In the end we went for daily differential, and weekly full backup.

If you need to restore from incremental, you'll need every incremental since last full backup. Whereas if you need to restore from differential, you need only the full backup and last differential.

That was kind of the winner for me...

It would work with a monthly full and intermediate differentials, and probably reduce the amount of time for processing jobs quite considerably.

 

 

DT

[jjohnsoncantell]

i must be thinking of another strategy because i thought even with doing daily incrementals and weekly differentials you would still need only the differentials since main backup to bring it back to date... Can you please clarify for me?

[DT2]

That's correct, in your case you'd be better simplifying the process and sticking with monthly/weekly full backups and differentials in between.

Given that your differential is smaller/faster than the incremental, it would make sense to keep it simple.

 

DT

[jjohnsoncantell]

problem we have is where the backup is well into two tapes its very inconvenient to come in over the weekend and change them over for the backup and then again for the verify.... Any suggestions?

[DT2]

I guess you have to review your options, is tape a suitable media or would backup to disk serve a better purpose? That way, the backup to disk could verify, complete and you can then write that info back to tape at your convenience. Backup strategies are very much like penises, we all have our own (well, at least 1 in 2 of us do) and what works for one, might not work for another

 

 

DT

[laserblazer]

Backup strategies are very much like penises

 

Mine's not very big so I can do a full backup every night.

[Naughty_Nigel]

I guess you have to review your options, is tape a suitable media or would backup to disk serve a better purpose? That way, the backup to disk could verify, complete and you can then write that info back to tape at your convenience. Backup strategies are very much like penises, we all have our own (well, at least 1 in 2 of us do) and what works for one, might not work for another

 

 

DT

 

What an analagy?

 

It depends a lot on the backup software that you use. We have used Retrospect for about ten years now, which only performs a complete backup onto new media when requested. Otherwise it does a daily incremental backup, and you just keep addng tapes as and when required.

 

Only the latest backup is verified, so you don't need to swap tapes for verification unless two tapes are needed for the backup.

 

If a restore is required, the catalogue provides a list of restore points, so you can choose when to restore from.

 

Regarding backup media, if you are currently using tape, you could add a second drive, so that when Tape 1 is full, Tape 2 will take over. This will also simplify verification.

 

You don't state which type of tape drive you are using, but if (say) you are using LTO2, you could add an LTO3 drive, which has double the capacity (and is faster), and can also read and write to LTO2 tapes. (An LTO4 drive can read LTO2 tapes, but cannot write to them. However, the cost of LTO 2, 3 and 4 drives and media is currently very similar, so it would be a logical step.)

 

You can of course run multiple SCSI drives on one adaptor, but there is no reason why the second drive shouldn't be a SAS device.

 

Dependiing on your software, you can also copy between or consolidate backup sets if you have two drives.

 

Nigel.

Edited June 12, 2012 by Naughty_Nigel