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Fully use RAM/CPU with (single) zip compressed profiles?

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Joined: Tue Nov 08, 2011 2:13 pm

Fully use RAM/CPU with (single) zip compressed profiles?

Post by morice »

I've been looking to create a few simple profiles that periodically create a single zip file stored by date, but i'm always a bit disappointed by the speed of it. It doesn't seem to be as efficient as it could be.

It appears to be using the Volume Shadow Copy Service (VSS), but i'm not sure how that works. Resource Monitor doesn't actually show a drive letter for the Shadow Volume activity, so is this something virtual?

In any case there seem to be two parts to the process: collecting the files, and then the slowest part is compressing. But there is a huge bottleneck with this, because the CPU is only at 10%, the drive's not doing much, and plenty of RAM is available.

On the other hand when using 7-zip for example, the archive is created immediately at close to 100% CPU usage - no additional steps. Completing the same thing in a fraction of the time.

Is there no way for Syncback to use such a super-efficient method?

For example, 1036 very small files in various folders using Syncback:
Deflate Level 0 - about 0:14
Deflate Level 1 - about 0:30
LZMA Level 1 - about 1:08
LZMA Level 5 - about 2:33

With 7-zip, LZMA Level 5 takes about 20 seconds. Matching the almost 10x difference in CPU usage.

One difference of course, when a file was in use. 7-zip couldn't do it. VSS presumably solves that, but is that causing the bottleneck?

Even at the cost of failing when files are in use, i would certainly welcome another option.
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