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I am doing a backup of my work and I'm looking for a program that can more efficiently compress files. The windows default compression program works fine, but it doesn't work as "smart" as i would like.

My files are basically entire snapshots of my work taken over the past few months as I do my regular complete backups. not a whole lot changes between the backups and many files are simply copies of each other.

My entire file set is approximately 15GB uncompressed, while individual snapshot backups (compressed using standard compression programs) are approximately 150 to 200 MB each (they typically increase in size with more recent dates). The total size of all the compressed snapshots is about 3GB. Due to the nature of the files, I expect a "smart" compression program to take the entire volume down to around 400-500 MB, that is, taking into account reasonable inefficiencies and extra space to compress the differences in the files.

Is there a compression program that will take advantage of the fact that many files are identical to achieve a much higher compression ratio than the standard windows compression program?

Thanks -Faken

Edit: Just finished a best compression of the entire volume using standard windows compression. It is only 10MB better than the compressed snapshots combined. In my opinion that is unacceptable knowing the nature of the files.

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On what version of windows? – John T Sep 4 '09 at 6:12
Heh, its vista... – Faken Sep 4 '09 at 6:16
Wouldn't switching to version control instead of those backups be better? I'm using git also for binary files and it works really well. I don't think it could compress it as good as 7z, but does it matter if it takes 150 MB or 300 MB? If not, I'd go for the easy of use and flexibility. – maaartinus Mar 14 '11 at 5:10
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3 Answers

up vote 5 down vote accepted

7-zip supports solid compression if I remember correctly, so it should compress a lot of nearly identical files very well.

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+1, and consider the default 7z format. – nik Sep 4 '09 at 6:12
I'll give it a try, I'll get back to you with the results. – Faken Sep 4 '09 at 6:12
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After 1 hour of compression at the highest settings I got a file size of 133MB. This is very impressive! My original aggressive estimate (which I didn't state) was a file size of about 150MB (this is opposed to my stated conservative estimate of 400-500MB). Looks like I'll be converting to 7z from now on! – Faken Sep 4 '09 at 7:17
Even if you need to stick to standard Zip format, 7-zip has a better yield than other popular compression tools (WinRAR, WinZip) with the highest efficiency setting. – christophem Sep 4 '09 at 9:06
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up vote 2 down vote

Windows Vista comes with Backup and Restore Center. It will do incremental backups of your files to avoid wasting space and having to create multiple backups. From the linked page:

Previously backed-up versions of files use only a bare minimum of disk space. If only a small part of a file changes (such as one slide in a presentation), only that portion gets tracked and saved.

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up vote 0 down vote

7-zip has one of the best compression algorithm around. I don't believe there's currently anything that beats 7-zip in compression (algorithm) so far.

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