Compression To Disk

[rsinsheimer]

Just updated from 7.6 to 7.7, hoping this issue was fixed, but no.

 

I have >700 GB of photographs in uncompressed form (TIFs and PSDs) that I back up with Retrospect.

 

These are highly compressible file formats -- if you .zip one of these they'll drop to 1/4 the size -- or less.

 

For whatever reason, when I turn on compression in Retrospect the saved size of the data set goes up about 30%.

 

Does anyone have any idea why that might be, and if there's a work-around? While backup space these days is relatively cheap, I'd rather not have to add more drives (I'm backing up onto a 1TB external USB drive, if that makes any difference) as the data set gets bigger.

 

-- Roger

[Lennart_T]

For whatever reason, when I turn on compression in Retrospect the saved size of the data set goes up about 30%.

Is that with a new or recycled media set in BOTH cases?

[Cygnis]

Does anyone have any idea why that might be, and if there's a work-around?

 

No direct workaround as far as I know, but here's a thread from the old Retrospect forum containing some background information:

http://forums.dantz.com/showtopic.php?tid/34710/pid/142557/post/last/m/1/

 

If you are using automated backups, and saving other types of data that do compress down well (i.e. not just the photographs that don't), you could backup using two different scripts: one with compression enabled, and one without. But that might be inconvenient and not worth the hassle.

 

Another option (again, probably very inconvenient) would be to ZIP them outside Retrospect before backing them up, but that would be a pretty big job with so many files, unless you can automate it somehow.

 

Is there any particular reason you don't compress the TIFs? I've always found LZW compression (which is lossless, and presumably available in many programs) to be fast and widely compatible. (Not that this will help you for all those existing images, but it might be a good option for future ones.)

Edited October 26, 2011 by Cygnis