Question about file compression

[Charlie98]

Windows offers a choice to 'compress this drive to save disk space' in drive management... is this generally a good idea? I understand the theory of file compression (sort of) and, as they say, nothing is free. What are the downsides?

I'm thinking primarily of file compression for on my HTPC rig. Would further compressing video files affect playback? I'm going to guess an M4v file is already fairly well compressed already...

 

[_Rick_]

That last bit is the crucial one.

I used to use compression, back when I only had 1.2GB of HDD, as freeing up hard drive space was absolutely paramount to anything else. But since then I've become very skeptical of real-time on-disk compression (and that's one of the reason's I did not buy a sandforce-based SSD). You might gain about .2% or so of additional compression, at the cost of quite a bit of CPU usage, which would indeed impact the playback capability - but probably in a very minor fashion, on that Pentium.

I would recommend - especially since you have 3 PCs in your household - to centralise storage, which reduced "wasted" free space. Basically get a mid-end NAS that takes all your HDDs (you might even want to build it yourself) and stick all disks inside. With LVM or ZFS, or some other magic tools, it should be quite easy to dynamically grow storage, add and replace disks, etc.
It also means you only have to run backups on a single machine.
But I really wouldn't bother with compressed FS in anything but special use cases, such as an SD card to which you write logs in text format, for example...

 

[Charlie98]

I've considered building a file server or NAS... but I don't know enough about it, quite honestly. I probably started buying components for my next build a little prematurely, before considering a FS/NAS.

 

[Lorne]

Video files, Image Files and music files rarely compress at all and will actually slow the system more, I am unsure about ISO because I havent tested those.
Somone chime on this?
The only time I have used the compression setup is right after a clean install then turn it back off again when its done.

What I have notice on the newer hardware is compression doesnt do much any more but give a small portion of drive space back.
But on older hardware especially laptops is that compression helps throughput of the slower HDD (Small file to load) by throwing more of the workload onto the CPU (decompressing the file before run).

 

[alzan]

Video files, Image Files and music files rarely compress at all and will actually slow the system more, I am unsure about ISO because I havent tested those.
Somone chime on this?
The only time I have used the compression setup is right after a clean install then turn it back off again when its done.

What I have notice on the newer hardware is compression doesnt do much any more but give a small portion of drive space back.
But on older hardware especially laptops is that compression helps throughput of the slower HDD (Small file to load) by throwing more of the workload onto the CPU (decompressing the file before run).

Just from a quick Google lookup and perusal it appears ISO's are not compressed which matches my limited experience with them. The reigning opinion in the links I read say that while you can compress an ISO it would be useless as anything other than a backup in that form.

I've never found any value to trying to further compress video/music/image files.

 

[sm625]

Any core 2 era or newer machine with any type of HDD or SSD will perform the same or even faster using compression. Sure, it takes cpu cycles to compress data, but on the other hand you save time by reducing the amount of data that has to go out over the slow SATA port.