Minimize tape back-and-forth motion

[arnstein]

I have created a Retrospect backup script that references 11 disk drive partitions (volumes) as its source. The script references a backup set of tape cartridges for its destination. The script sets the verify option to "on."

 

When this script executes a backup session, the tape drive seems to do the following:

1. Copy from first disk partition (volume) to tape.

2. Rewind tape.

3. Verify what was written to tape in step 1.

4. Copy from second disk partition (volume) to tape.

5. Rewind tape.

6. Verify what was written to tape in step 4.

etc.

 

This is a lot of rewinding. On a day when my disk data has not changed much, the tape drive spends more time positioning the tape than it does reading and writing data.

 

Can I force Retrospect to copy data from all disk partitions (volumes) to tape, and then rewind (once) and then verify everything written to the tape?

 

If this is not possible, another strategy would be to set the verify option of my backup script to "off." In this case, I would want to verify the tape in a separate process. Can this be automated (scheduled)? If I use this method, can I do a byte-by-byte compare during the verify operation?

[AmyJ]

Quote:

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Can I force Retrospect to copy data from all disk partitions (volumes) to tape, and then rewind (once) and then verify everything written to the tape?

 

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Retrospect's verification pass mimics an actual restore, in that it ask you to verify the media just like you would have to in a restore, in order. Retrospect will backup/verify a single source before moving on to the next. It is not possible to verify all sources in one pass.

 

Quote:

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If this is not possible, another strategy would be to set the verify option of my backup script to "off." In this case, I would want to verify the tape in a separate process. Can this be automated (scheduled)? If I use this method, can I do a byte-by-byte compare during the verify operation?

 

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Turning off verification during backup is not recommended. The compare pass will do a byte by byte file comparison to ensure the copied file exactly matches the original. You can manually verify the contents of the entire backup set through Tools > Verify, however, this process only ensures that all files are readable - not that the match the originals. It is not possible to compare backup files against the originals if the backup has been stopped or has completed without verification.

[arnstein]

Thanks for the info Amy.

 

I've been thinking about using a feature of Microsoft Windows called "Mount Points" Basically, I could arrange for a single disk partition (call it G:) to contain multiple mount points. Each mount point would point to a different disk partition.

 

I could create a Retrospect backup script that would use G: as its source. My intent would be to get Retrospect to backup G: and all the partitions that G:'s mount points point to. If this works, it would eliminate the extra back-and-forth tape motions during backup. It might also simplify complete recovery from disk failure, since I could restore G: from tape, and this would (presumably) restore all the partitions that G:'s mount points point to.

 

Is this supported in Retrospect Pro? Is it advisable?

[AmyJ]

Sure - that will work. Check out the following article for a little additional info:

 

http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27422

[BitPusher]

Hello Amy,

 

I am a user of Retrospect Professional V6.0 and I have been following this thread because I would also like to find a way to minimize some of the tape rewind time for my 12 partitions.

 

In your reply to post #28327 from arnstein, you seemed to indicate that he could use the Windows Mount Points to back up the data for his entire system by backing up the drive containing all of the Mount Points to other volumes which would essentially write all of the data and then rewind once to verify that data.

 

Doing some experimenting with Mount Points and Retrospect tonight, it doesn't appear that what he (and I) want to do will work with Retrospect Professional V6. Both my printed an online documentation indicate that if a volume is backed up that contains Mount Points, the data of the mounted volumes will NOT be backed up unless they are individually specified. In other words, backing up a volume with Mount Points only backs up the "empty" Mount Point Folders and not the data in the volumes to which they link. If this is the case, it seems to me that for each of the individually specified mounted volumes will be backed up, then rewound, then verified which would result in the same situation as not using Mount Points.

 

Have I overlooked something or is this maybe a feature that only works in Retrospect Professional V6.5? If following the Mount Point "links" is a new feature in Retrospect Professional V6.5 I will be upgrading tomorrow. If not, I would like to see a new feature added to a future version that will give the option of backing up and verifying data by following the Mount Point "links".

 

In any event, would you please clarify your response to this issue.

 

Thank You,

Carl E. Johnson

[AmyJ]

I misread the post, and was thinking of mounted volumes, rather then mount points. We treat mount points like empty folders, meaning that we don't resolve the mount point back to the source.

[BitPusher]

Thanks for the prompt clairification Amy.

 

It would be nice if Retrospect would follow the Mount Point links, but in the meanwhile when I get some time I will try to combine some of my partitions to ameliorate the amount of tape rewind time.

 

Thanks again,

Carl E. Johnson