Linux – btrfs: how to calculate btrfs compression space savings

btrfslinux

I've enabled compression (mounted with compress=lzo) for my btrfs partition and used it for a while.

I'm curious about how much benefit the compression brought me and am interested in the saved space value (sum of all file sizes) - (actual used space).

Is there any straightforward way to get this value, or would I have to write a script that sums up e.g. df output and compres it to btrfs filesystem dfoutput?

Best Answer

In Debian/Ubuntu:

apt install btrfs-compsize
compsize /mnt/btrfs-partition

In Fedora:

dnf install compsize
compsize /mnt/btrfs-partition

output is like this:

Processed 123574 files, 1399139 regular extents (1399139 refs), 69614 inline.
Type       Perc     Disk Usage   Uncompressed Referenced  
TOTAL       73%      211G         289G         289G       
none       100%      174G         174G         174G       
lzo         32%       37G         115G         115G

Related Solutions

Clear unused space with zeros (btrfs)

The correct and "smart" way to clear the free space is using:

fstrim /mountpoint

Use this on a mounted filesystem.

It's important to note that there is no security advantage to this. If you wish to clear your disk for security, back up your files, zero the entire disk with a command like "shred" and then restore your files.

However the solution works fine if your disk is a thin provision on a sparse filesystem and you wish to recover the unused space.

Ubuntu – How to enable btrfs zstd compression

You also need to update btrfs-progs to a version that supports zstd. Zstd support was initially added in version 4.13.

Best Answer

Related Solutions

Clear unused space with zeros (btrfs)

Ubuntu – How to enable btrfs zstd compression

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