Multiple Media Sets on 1 LTO

[philipal]

I am new to using Retrospect and I'm a little fuzzy on how these Media Sets work. I am using an LTO Tape drive to make backup copies of clients' work. Each client has about 200 Gb worth of data, so I can fit about 4 projects on each tape. Can I create a different Media Set for each client and have multiple Media Sets on a single tape, or do I just create 1 Media Set per tape and put multiple projects in that Media Set?

[rhwalker]

It appears, because you are using the "newspeak" language of "Media Sets" rather than the older, formerly politically-correct term of "Backup Sets", that you are probably using Retrospect 8.x for Macintosh. You would probably get more responses if you posted in that forum:

Retrospect 8 for Macintosh

 

Can I create a different Media Set for each client

Yes

 

and have multiple Media Sets on a single tape,

No

 

or do I just create 1 Media Set per tape and put multiple projects in that Media Set?

That would work.

 

Here is the paradigm, perhaps it will help you get your head around this in the absence of User Manual documentation for Retrospect 8:

 

A Media Set is a database (container) into which you dump files and metadata (permissions, ownership, etc.) information. Many types of Media Sets (such as tape media sets) have multiple parts ("members"). Each tape for that Media Set is a "member" of the Media Set, and the members are used (and numbered) sequentially as the Media Set (database) grows.

 

The "catalog" is a database index into the Media Set, and tells Retrospect where the various files in the Media Set are located, etc.

 

So, because each tape is a "member" of only one Media Set, you can't have multiple Media Sets on a tape. As a practical matter, the serial nature of the tape medium would prevent appending to all Media Sets on the tape except the last, and there would be labeling difficulties with the tape (because the tape label at the start of the tape indicates the tape name, which encodes the Media Set and member number within that Media Set) if multiple Media Sets could somehow be on a single tape member.

 

You could either set up Media Sets with separate tapes as members, one for each client, or else you could set up a single Media Set and dump everything into that.

 

It all depends on how you view your data, and whether you want to put all eggs in the same basket (tapes do fail).

 

From your description of your data, it would seem that you probably want to have one Media Set per client, perhaps even with multiple tape members for each client as the number of projects for each client grows, unless you have many clients with only a small amount of data.

 

The advantage of grouping things by client would let you pick up (and store offsite) a small number of tapes for the client without having to know which specific tape is needed for a particular project.

 

The other consideration is whether you back up multiple clients each day, in which case you could be swapping a lot of tapes (get an autoloader, it will change your life. Really), or if, instead, you are viewing the tapes as an archive repository to which you roll out projects as they are completed, rather than a daily incremental backup of your computer(s).

 

Hope this helps, and yes, documentation would be nice, but that's just wishful thinking. Hmmm... documentation, what a concept.

 

Russ

[philipal]

Russ, that clears things up nicely. Thanks for the help.