So.... what's stopping you doing a quick test to find out what is best for you? Take a chunk of your data, and copy it into a few volumes, each with a different compression config, and compare the results. Although reading the stuff you posted -- it really sounds like the only sensible options are lz4 or gzip. I ran a quick test using (non-zfs) equivalents of various compression tools, over a 2.0G filesystem image. (ie. hoping that represents a fair variety of binary+text files) lz4 1.7s 221M lz4 -6 10s 189M gzip 25s 151M bzip2 54s 135M 7z 147s 102M xz 253s 103M So if space is really at a premium, you're better off using an archive tool to compress everything, rather than zfs' built-in compression. You can store almost twice as much that way! But otherwise, gzip is better than lz4, but at significantly slower performance. -Toby On 19 November 2014 12:17, Peter Ross <Petros.Listig@fdrive.com.au> wrote:

Hi all,

I want to reorganize some backups and use ZFS snapshots copied to a "backup NAS" (I am having).

Traditionally some zfs were sent as a .tgz to the NAS.

I want to use ZFS compression on the box instead and look for the best method to compress it. Space savings are important, speed isn't.

Below the man page describing the compression methods available.

Do you have experience to recommend a method working well?

I do not want to "muck around" and change too much because it is Terabytes worth of data and I do not want to reconfigure too often.

I do not use compression on my production systems a lot so I do not have too much experience with it.

I have a few "not frequently used/non-critical" filesystems with lz4 - but that's it. Speed-wise it did not seem to matter much compared to uncompressed filesystems (but I did not benchmark properly)

Thanks for any advice Peter

compression=on | off | lzjb | gzip | gzip-N | zle | lz4 Controls the compression algorithm used for this dataset. The lzjb compression algorithm is optimized for performance while providing decent data compression. Setting compression to on uses the lzjb com- pression algorithm. The gzip compression algorithm uses the same com- pression as the gzip(1) command. You can specify the gzip level by using the value gzip-N where N is an integer from 1 (fastest) to 9 (best compression ratio). Currently, gzip is equivalent to gzip-6 (which is also the default for gzip(1)). The zle compression algo- rithm compresses runs of zeros.

The lz4 compression algorithm is a high-performance replacement for the lzjb algorithm. It features significantly faster compression and decompression, as well as a moderately higher compression ratio than lzjb, but can only be used on pools with the lz4_compress feature set to enabled. See zpool-features(7) for details on ZFS feature flags and the lz4_compress feature.

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