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Compression not working


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I do an immediate File Backup of my internal HD on my external Firewire HD. I set Retrospect to "All Files" and Compression to on, as I have done many times before, in particular I remember verifying this a few months ago by noting that the size of Backup Set A is much smaller than all the files on my internal HD. However, this time I find that the file, at 104 GB, is very slightly bigger! Just before the backup process started I saw a confirmation from Retrospect that Compression was on, and during the backup process Retrospect's dialogue box reported on the current degree of compression which started at 50% and fell to about 25% after 20 minutes, when I went to bed. The only recent difference is that I replaced my external Firewire HD (partitioned) by an identical model but bigger with Retrospect using a Partition of 150 GB.

 

Why will it not compress please?

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Can we assume, since you are comparing the size of your backup set to the size of your source volume, that you are performing Recycle Backups? (A Normal Backup will add new or changed files to the backup set without deleting the previous versions, so the backup set will continue to grow, whether or not the files added to it are compressed.)

 

Have there been any changes to the files on your source volume, such as the inclusion of files that were already compressed by some other software?

 

How often have you compared the size of your file backup sets to the source volume?

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1. Can we assume, since you are comparing the size of your backup set to the size of your source volume, that you are performing Recycle Backups? (A Normal Backup will add new or changed files to the backup set without deleting the previous versions, so the backup set will continue to grow, whether or not the files added to it are compressed.)

 

2. Have there been any changes to the files on your source volume, such as the inclusion of files that were already compressed by some other software?

 

3. How often have you compared the size of your file backup sets to the source volume?

 


 

1. No. I am performing an Immediate File Backup. (I haven't come across Recycle Backups.) Also, because I had installed a new Firewire external HD, the drive was empty, so it was an Initial Backup (I think it's called that) - it was not an Incremental Backup.

 

2. No changes (except of course the contents of files changed as I used the computer).

 

3. The last time I compared was about six months ago, and several times previously over about a year (using the old HD). The backups were about half the size of the total of files backed up.

 

I did not mention in my earlier post that after the backup was complete, Retrospect's dialogue box recorded a compression of 0%. I have made two backups in case the first was unique, starting each with an empty backup HD. Same result.

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