I Have A Squashfs Question.

[hightokeinyoda]

I have approximately 2TB of media that i would like to make a backup of and store on a local backup server.

due to circumstances beyond my control it is rather limited in space approximately 1TB of storage capacity.

i was wondering if i could use squashfs to make a compressed copy of the 2TB media partition so i could store it on the 1TB backup server.

ive read squashfs is highly efficient and effective at comprising a full linux live distribution.

my question really boils down to this, will the resulting compressed copy fit on the 1TB drive?

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[Snowhog]

This might be helpful: https://www.tldp.org/HOWTO/SquashFS-...gandusing.html

[jlittle]

Firstly, if by "media" you mean music, pictures, and video, they are typically already compressed, and any further lossless compression will be marginal, nowhere near the 50% you seek. To get that I imagine you'd have to recode the media at lower quality settings, a complex task requiring expertise in each media format you have.

Secondly, squashfs is optimized for decompression on "constrained" environments so that it will run well on anything. IMO you should be looking at compressors generally. IME

• 7z (using p7zip) has the highest compression ratio, but xz (using xz -T 0) is close behind
• p7zip used to be slower than xz on my computer, but running some tests now p7zip is slightly faster
• 7z and xz are both much better than gzip on some types of data
• gzip is much faster. (p7zip and xz -T 0 use all 8 threads my CPU has, gzip is faster using just one. If p7zip and xz had to run single threaded they'd be really slow.)
• on a directory with about 1 GB of photos, every method I tried saved only 5 MB; no use at all

[oshunluvr]

Just generally and IMO, you'll never get near 50% compression no matter what unless everything is a text file.

[jlittle]

Having slept on it, I think you've thought of squashfs because you want what's called "transparent compression", store the data and the fs compresses them behind the scenes.

NTFS and zfs have been able to do this for a long time, and btrfs can do it now, but ext4 and xfs don't (IIUC something called LVM VDO hasn't landed in Ubuntu yet, being a red hat thing, and you can have ext4 or xfs on top of zfs, I suppose).

But, images, video, and music are already compressed, and fs compression won't help.

[hightokeinyoda]

Having slept on it, I think you've thought of squashfs because you want what's called "transparent compression", store the data and the fs compresses them behind the scenes.

NTFS and zfs have been able to do this for a long time, and btrfs can do it now, but ext4 and xfs don't (IIUC something called LVM VDO hasn't landed in Ubuntu yet, being a red hat thing, and you can have ext4 or xfs on top of zfs, I suppose).

But, images, video, and music are already compressed, and fs compression won't help.

thanks pal, looks like its time to stock up on some good capacity hdd's and a new backup server or two

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