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Created: 10 Oct 2012 | 5 comments

OK, now I'm really getting all confused, or showing my lack of knowledge of backup configuration.

So I've created two Backup2Disk folders. But I hear you saying I don't need to do that, only 2 Media sets? Do those Media sets point to the same Backup2Disk folder? What exactly is the difference between a Media set and a Backup device?

Also, should I use differential or incremental? Will I then have the one-time Full backup and then the ongoing differntial or incremental? I was imagining one set of files, but I'm thinking that's not right. I guess for DR and ease of management I should use differential, because that gives me a single extra file that would grow every day, whereas I would have 365 small incrementals after a year? Should I use archive bit or modified time?

Sorry for all the details, but as I think about it, all my previous knowledge seems to have fled me....

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pkh's picture

What exactly is the difference between a Media set and a Backup device?

A media set is a logical container in BE which you can set the OPP and AP for a media.  A B2D folder is a physical folder/container to hold the actual media.  They are independent of each other.  Multiple jobs can share media sets and B2D folder and they can use them in any combination.  For example, Job1 can use MediaSet1 and B2D-1, Job2 can use MediaSet2 and B2D-1, Job3 can use MediaSet1 and B2D-2.

should I use differential or incremental?

My article below should help

Should I use archive bit or modified time?

The modified time method should be faster

I would strongly suggest that you read the Data Mangement section of the Admin Guide.

Colin Weaver's picture

I would recommend that you run periodic full backups (say once a week, one every 2 weeks etc), don't run a one time full backup and then only use Incremental or differnetial sets going onwards, as if anything affects that base full (or the sequence of full and incremental sets) then you won't be able to restore.

Other than that please read the article by pkh and probably the section on Media management in teh administrators guide as well.

maitakeboy's picture

Thanks pkh and Colin, I've been using BE for 12 years, but since I don't often actually configure backups, I forget some of the niceties when I have to get back to it. Thanks for the refresh.

My questions center around my desire to make my offsite syncing feasible. I think, again, I was getting myself tied in knots since I only configure backups every three years or so. But after a good night's sleep, I think I have most of the cobwebs cleared. I was mistakenly thinking that the differential/incremental would actually overwrite the particular files affected in the full backup, which of course is preposterous, but I was getting a little bleary by that time. Obviously, a full with differentials will be my best DR setup.

The consideration, though, is with the syncing over a WAN connection. My full backup is 2.4 TB. Syncing that over even a 20MB link is not really feasible on a regular basis. I understand, Colin, your cautioning about depending upon a single base full backup, which had entered my mind. The problem, however, is that doing a new full backup creates backup files with new timestamps, even though many of the files may not have changed. So evry time I do a new full backup, I have to sync that full 2.4 TB. I was trying to avoid that, as it really isn't feasible. The reality is, I probably have way too many unchanging files that are in my "production" backup, that really should exist only in an archive. I would guess that maybe only 20% ofmy full backup is actually changing, at best. Any thoughts?

As far as archive vs modified time, were you referring to the actual backup time in saying that modified time is faster? What happens to the archive bit, then? Or does it just become irrelevant?

Colin Weaver's picture

If you are looking at Wan links then a Private Cloud setup with multiple media severs and DeDuplication would in theory be the way to go.

The other option to look into Synthetic Backusp where you run one fulll folowed by an incremental and then run a secondary process to combine the two into a new full. Thsi is not really a WAN solution though

Both the above would need extra hardwareor licenses

Note although some seem to think that combining a synthetic with DeDup might be a good idea I am not sure it is needed or if there is any benefit to using both.

pkh's picture

If I am not mistaken, you cannot do synthetic backups when you backup to a dedup folder.