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mcmeini

Software Compression doesn't work

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Hello!

 

 

I have a Problem with my Retrospect Professional 7.7.562 (64-bit).

 

Although I have activated the Software compression in the backup script, the data of the automatic backup isn't compressed on the external hard disk where I save the backup.

 

I have to save 1,79 TB of data and the external hard disk for backup has a space of 1,81 TB and retrospect ask for a second drive. This also after a recycling backup.

 

What is wrong that it doesn't work?

 

 

Thank you and best regards

 

Anton

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Files that already are compressed can't be compressed more. Such files are video files, most music files, most picture filer and zip files. Just to name the most common files.

 

Files that compresses best are pure text files (not to be confused with word processor documents).

 

So, what kind of files are you trying to backup?

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It is a mixture of amost every filetypes (pictures, videos, music, documents, zip files).

 

There a approximately half or at least one quarter of the files documents (word, text, webpages and so on).

 

I can't imagine that retrospect isn't able to save it with compression. At the end of the backup it says 0 % compression.

 

I also tried it with the current version 12. There is the same problem.

 

Thank you

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There a approximately half or at least one quarter of the files documents (word, text, webpages and so on).

 

 

 

Is that in terms of file count or byte count?

 

If you have a hundred video files and a hundred text files, the latter tends to be much smaller. So the resulting compression may very well be 0% (rounded down).

 

If you have 100 GB of video and 100 GB of text files, you should see maybe 25-40% compression. (Note that word processing documents are not text files in this context.)

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It is in terms of byte Count. I have looked it up in the windows explorer and there are approximately 1,5 TB of Videos, 200 GB documents, 10 GB Music and the rest is other file types.

 

In my opinion there should be at least 5 % compression.

 

The data hard disk of the computer is full with 1,79 TB and the external back drive has a capacity of 1,81 TB. After a recycling backup, the external backup disk is full, so there is no compression (like the program retrospect says it too) . A second normal backup is therefore not possible.

 

What is wrong that it doesn't work?

 

Thank you

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Try backing up only the documents and see if you get any compression.

 

In addition to the raw data of the file's contents, Retrospect must also backup a lot of metadata: File name, file path, dates, permissions and ACLs for instance.

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(Sorry for the late reply, I did not get notified of you reply by email for some reason.)

 

The conclusion is that software compression does indeed work, but that your full backup contains too few compressible files to be of any significance. 

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It's possible that mcmeini is confused by the two different possible ways of calculating storage capacity, as described in this post.  It's early in the morning for me, but it appears that at least the Retrospect Mac version of the Dashboard uses the "disk drive vendor" way in the Backups pane daily totals, but uses the "computer people" way in the Storage pane totals.  That would mean that mcmeini doesn't have as much available space on his/her external HDD as he/she thinks.

 

This post was sponsored by the World Disk Drive Vendors Association, which would like mcmeini to purchase an additional external HDD (insert appropriate smiley here).  It could instead have been sponsored by Retrospect Inc., who would no doubt like mcmeini to upgrade to Retrospect Windows 12 (insert appropriate smiley here) so he/she could take advantage of the improved Backup Set grooming described in the first bulleted item here or the second bulleted item here.

 

P.S.: It was too early in the morning for me; I got the "ways" reversed during my walk from my Mac Pro "backup server" to the MacBook Pro from which I post—so I have now corrected the second sentence in the first paragraph.  However my general point is unchanged; Retrospect uses the "disk drive vendor" calculation way—which gives a higher number of TBs—in some places, but uses the "computer people" calculation way—which gives a lower number of TBs—in other places.  mcmeini should beware of this.

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