Default zfs compression

[ieronymous]

I d like to know which is the type of compression used when you set it to auto upon installation, since running the command
:~# zfs get compression rpool
NAME PROPERTY VALUE SOURCE
rpool compression on local
doesnt give any info.

PS I know that I can manually set it with zfs set compression=lz4 zpool_name but how can I check the type of compression afterwards

Thank you

 

[aaron]

From man zfsprops:

     compression=on|off|gzip|gzip-N|lz4|lzjb|zle|zstd|zstd-N|zstd-fast|zstd-fast-N
       Controls the compression algorithm used for this dataset.

       Setting compression to on indicates that the current default compression algorithm should be used.  The
       default balances compression and decompression speed, with compression ratio and is expected to work well
       on a wide variety of workloads.  Unlike all other settings for this property, on does not select a fixed
       compression type.  As new compression algorithms are added to ZFS and enabled on a pool, the default com‐
       pression algorithm may change.  The current default compression algorithm is either lzjb or, if the
       lz4_compress feature is enabled, lz4.

So the default should be lz4

 

[ieronymous]

From man zfsprops:

     compression=on|off|gzip|gzip-N|lz4|lzjb|zle|zstd|zstd-N|zstd-fast|zstd-fast-N
       Controls the compression algorithm used for this dataset.

       Setting compression to on indicates that the current default compression algorithm should be used.  The
       default balances compression and decompression speed, with compression ratio and is expected to work well
       on a wide variety of workloads.  Unlike all other settings for this property, on does not select a fixed
       compression type.  As new compression algorithms are added to ZFS and enabled on a pool, the default com‐
       pression algorithm may change.  The current default compression algorithm is either lzjb or, if the
       lz4_compress feature is enabled, lz4.

So the default should be lz4

Thanks but there got to be a way to check it

 

[Dunuin]

Thanks but there got to be a way to check it

I don't see the point. If you want to make sure that lz4 is used and not lzjb, why not setting "compression=lz4" for that pool directly? All childs will inherit that compression so you know what exactly will be used.

Edit:
If you really want to check it:
zpool get all YourPool | grep feature@lz4_compress
That will tell you if the "lz4_compress" feature is enabled. If it is enabled lz4 should be used by default if you refer to the documentation:

The current default compression algorithm is either lzjb or, if the lz4_compress feature is enabled, lz4.

 

[ieronymous]

I don't see the point.

No other than I want to know once more ......

Edit:
If you really want to check it:

I like the edit part

 

[Tmanok]

As mentioned by LnXBill about 5 years ago, you can verify compression with the get feature command offered in OpenZFS on Linux.

root@proxmox:/# zpool get feature@lz4_compress rpool
NAME   PROPERTY              VALUE                 SOURCE
rpool  feature@lz4_compress  active                local

https://forum.proxmox.com/threads/what-is-the-zfs-defaultcompression-when-i-say-on.38730/
Cheers,

Tmanok

 

[LnxBil]

Funny what you once knew ...

 

[Tmanok]

Funny what you once knew ...

Sometimes I return to old posts and think "This is fascinating!" only to find out that I posted the solution or a follow-up comment a couple years ago. :O Hah!

 

[Dunuin]

Sometimes I return to old posts and think "This is fascinating!" only to find out that I posted the solution or a follow-up comment a couple years ago. :O Hah!

Yeah, sometimes when I search for a solution for a problem all google can find are thread posted by me in some forums along time ago.

 

[Tmanok]

Yeah, sometimes when I search for a solution for a problem all google can find are thread posted by me in some forums along time ago.

To some, that's adequate documentation Hahaha... For me, I mix between Google Search and Confluence. Impossible to document all possibilities into Confluence, good to have PVE forums from time to time.

 

[LnxBil]

Yeah, sometimes when I search for a solution for a problem all google can find are thread posted by me in some forums along time ago.

same! Therefore I also reply to my own threads if I find a solution for the future-me to find and enjoy.

 

[Tmanok]

same! Therefore I also reply to my own threads if I find a solution for the future-me to find and enjoy.

Goodness, we sound so senile and yet it's so true!