How does Retrospect identify volumes?

[pls2000]

How does Retrospect identify volumes during backup? In particular, I'm interested in the following cases:

 

1. An external drive mounts as H on the machine where Retrospect is running and is backed up. Later, the same drive mounts as J:. I change the backup script to use the new drive letter. Will Retrospect recognize that this is the same volume and that most of the files are already backed up?

 

2. An external drive mounts as drive H on machine X which has a retrospect client running and is backed up. I move the drive to the machine where retrospect is running and it mounts as drive L. I change the backup script to use the new drive letter. Will Retrospect recognize that this is the same volume and that most of the files are already backed up?

 

3. An external drive is mounted as H on machine Y which does not have a retrospect client. The drive is shared as Drive1. I go into retrospect and create a volume referencing the share by UNC name \\Y\Drive1 and backup it. I later move the drive to the machine where Retrospect is running where it mounts as drive H. I change the backup script to refer to H and run a backup. Will Retrospect recognize that this is the same volume and that most of the files are already backed up?

 

  Thanks,

    ++PLS

[Lennart_T]

1. You really ask two questions.

1a, No Retrospect will see them as two different volumes. So if you look in Retrospect, you will see both H: and J: for that client.

1b, Yes, Retrospect will see that the files are already backed up.

 

2. Here, too, you ask two questions.

2a. No Retrospect will see them as two different volumes.

2b. That depends on the OS difference. If both client run the same OS (and possibly Retrospect client) then the files will not be backed up again. If the clients runs different OS (XP vs. Vista vs. 7 vs. 8) then Retrospect will see them as different files due to different metadata.

http://en.wikipedia.org/wiki/Metadata

 

3. Here, too, you ask two questions.

3a. No Retrospect will see them as two different volumes.

3b. No, since metadata is fundamentally different between an SMB share and a local drive.

[pls2000]

Thank you very much.

 

I'm aware that I was asking two questions. And I'm surprised by the answer, so please let me ask two more.

 

1. Apparently which volume contains the file is not a factor in determining if the file is backed up. How does retrospect match backed up files against file on the volume being backed up?

 

2. How does the option "Match only files in same location" affect that answer?

 

  Thanks,

    ++PLS

[Lennart_T]

1. I don't think it does. I think it only looks at the files' metadata: name, size, date and so on.

 

2. I think it looks at the path, less the drive letter. So if the path is different, the file will be backed up again, even if it is another copy of the same file.

 

By the way: I wonder why you would move the same drive around to all those different places? I would make sure it is at the same location every time the backup runs.

If that is not what you intend to do, what is it you intend to do that needs these questions answered?

[pls2000]

It's pretty much as described in my first question. I have two external USB disk drives that are used with several different machines and stored in a safe when not in use. I'm exploring options for backing them up.

[pls2000]

Thanks for the help, BTW. I'm asking pretty basic questions but I've never seen this subject document by the Retrospect publishers. It's a little hard to lay out backup procedures without knowing this stuff.

 

  Thanks

[Lennart_T]

As I wrote earlier: I always make sure my external disk is in the same place when the backup runs. In my case I connect it to the Retrospect server using Firewire 800. That avoids dragging lots of data over the network.

Good luck.

[Scillonian]

What are the external disks used for?

 

If they are for backups a better scenario may be to use them to make backup of the Retrospect backup for an off-site copy.

 

If they are used for working copies of files then an option may be to replace them with a NAS device and repurpose the two external disks for off-site backups of the files stored on the NAS.

 

Lennart's advice to always backup the external disks from a single machine, preferably the one running Retrospect, is sound advice. It is possible to set Retrospect to only backup specific drives on a client machine so excluding the external disk if it happens to be connected to a client when the backup runs it will be ignored.

[pls2000]

>What are the external disks used for?

 

As I said, they spend most of their time stored in a safe. The data on it is sensitive. The normal retorspect backup in encrypted so I'm not worried about having the data in the R backup set. That said, one of this things I'm considering is simply mirroring the drive to another USB drive that lives in a different safe. I do consider that R keeps multiple versions of change file to be a plust, though. This is all still under consideration.