Question about "Match only same location"

[karma]

My understanding is, that when "Match only same location" is OFF (default setting), then if a file with a particular name has been backed up on some other client (in the same Backup Set), if a file with the exact same name and same modification date is found while backing up *this* client that the file will NOT be backed up.

 

Is that correct?

 

I have noticed that a client's backups of a particular volume are small compared to the size of the data; even when performing a first backup of that volume. Yes, many of the files exist on another client (previously backed up in the same Backup Set). So that is what I guess is happening.

 

My next question is:

If this is true, then the backup set for the second client does not contain some of the files that are in the first client. I can see this by browsing the backup set. What would happen if I had to do a complete Restore from the second client, that does not have all the files? Does it "know" that the files were on the first client, and would restore them from there?

[rhwalker]

My understanding is, that when "Match only same location" is OFF (default setting), then if a file with a particular name has been backed up on some other client (in the same Backup Set), if a file with the exact same name and same modification date is found while backing up *this* client that the file will NOT be backed up.

 

Is that correct?

No, and your speculation is not even close. From the Retrospect 6.0/6.1 for Macintosh Users Guide (you really ought to try looking in the User's Guide for answers to questions like this - it's quite good):

 

Match only same location: This option is only available if “Match source files to catalog†is selected. It makes Retrospect more strictly match otherwise “identical†files from a source to a destination. (Normally, files are considered identical files when they have the same criteria described above in “Match source files to Catalog Fileâ€.) When this option is selected, Retrospect uses the unique (and hidden) Mac OS file identification number as an additional part of the matching criteria. This causes separate copies of otherwise-identical files to not match. (And unmatched files get backed up, so your backups are larger and slower.)

 

By default, this option is off and you should keep it that way unless you have a specific need to change it.

Russ

[karma]

Yes, you're right, I should have looked in the help file. Sorry.

 

However, now having done so then is this correct (when "Match only same location" is OFF):

 

1. This only applies to files within a particular backup client?

 

2. Let's say I have a folder named Project 1 with a bunch of files in it. At some point, I duplicate the folder, name it Project 2, and only modify a few files. Same with Project 3, Project 4, etc.

 

So when this is backed up (for the first time to a new backup set), it would back up all the files in one of the project folders, and then just the few changed files in each of the other project folders?

 

3. Assuming you had to do a full restore, it would put the additional duplicate copies of the files back where they are supposed to go, even though it didn't copy them to the backup set?

 

Really, I'm just trying to understand why a folder having 8 GB of files in it (and having 91,009 files when examined in the Windows Properties) backs up to a fresh Backup Set (no previous backups to compare to) and only shows 3,874 files and about 4 GB backed up. Yes, there are many duplicates of the same files in there, in different Project folders as described. Thanks.

[rhwalker]

Yes, you're right, I should have looked in the help file. Sorry.

 

However, now having done so then is this correct (when "Match only same location" is OFF):

 

1. This only applies to files within a particular backup client?

No. Please re-read the manual page. It applies to all files for that backup script and matches against files in the backup set, even if they are from other clients or even local to the Retrospect machine.

 

2. Let's say I have a folder named Project 1 with a bunch of files in it. At some point, I duplicate the folder, name it Project 2, and only modify a few files. Same with Project 3, Project 4, etc.

 

So when this is backed up (for the first time to a new backup set), it would back up all the files in one of the project folders, and then just the few changed files in each of the other project folders?

Perhaps. It depends on the indicated parameters that are being matched, and you have not provided enough details.

 

For example, the owner of the original file may not be the one who did the duplication, causing the owner to change and perhaps, depending on setting of UMASK and ACL propagation, might cause other metadata to change. You have an overly simplistic view of "duplicate" and what makes two files the same, as viewed by the metadata.

 

3. Assuming you had to do a full restore, it would put the additional duplicate copies of the files back where they are supposed to go, even though it didn't copy them to the backup set?

Yes.