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A bit of story: I am hosting a few modified Linux distribution images, around 700MBs each. My server's free disk space is the main concern here, my current archive uses up roughly 16/20GBs of my disk space and I plan to add a few more in the near future.

Is there a method (readily available, say for the end-user's simplicity of extracting it) that can reduce the size of the images? Is there a type of compression? I have remembered some type of free format which can reduce sizes, but for the life of me cannot reference any (other than non-free Windows applications)

My goal is to reduce sizes by atleast 20%, 7-zip appears to only be able to compress it around 2% (on a compression level speed I am comfortable with, 5 out of 9).

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up vote 2 down vote accepted

Most distros are already crammed in the iso's; the bzip2'd data will not compress much further.

Why are you not comfortable with 7zip's maximum compression? It's a one-time thing after all. However, it will most likely not bring you from 2 to 20% reduction.

My best bet would be to reduce the contents of the iso. Presumably you are making a specific purpose live cd from which you can strip some big packages (openoffice?)? Or if it's some installable image, perhaps you can depend on the packages from the mother-distro's mirrors?

Another option is to increase diskspace or outsource part of the hosting to a service like S3.

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Ah - in the end my server is just a VPS, not a file host. A CDN seems more suited, just wanted to see if I can juice my server to do all it can do - so no wasted resources. Thank you. – Robert Renu. Jan 23 '11 at 8:58

I doubt it will do any good. Many of the distibution images are already compressed.

7zip is quite powerful and others won't do much better. Maybe you could serve images from network drive?

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Yes, it does seem there is not much more I can do. CDN it is. – Robert Renu. Jan 23 '11 at 8:58

Space is pretty cheap... If 16 to 20 GB is causing an issue, then I'd say you're in need of more. Consider a USB disk to store them. A NAS may be a good idea, too, if you want something more robust and available than adding storage with USB.

If your custom ISOs are all based on the same distos (or set of distros), you could consider making delta files of the original ISOs. This may save more space than compression.

But, really, add space. 20GB is nothing these days.

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Sadly my VPS host (Linode) requires me to purchase another node just for another 20GBs disk space or 200GBs bandwidth (or +6 for $120/year!), I hate that, why I was looking for a quick fix. – Robert Renu. Jan 23 '11 at 9:13
In that case I'd go with third-party storage as Joris said. – Cakemox Jan 23 '11 at 9:16

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