[pve-devel] [PATCH docs] Add section 'Compression in ZFS'

[Fabian Ebner]

Signed-off-by: Fabian Ebner <f.ebner at proxmox.com>
---
 local-zfs.adoc | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/local-zfs.adoc b/local-zfs.adoc
index 15a88bb..69979b5 100644
--- a/local-zfs.adoc
+++ b/local-zfs.adoc
@@ -180,7 +180,7 @@ underlying disk.
 
  zpool create -f -o ashift=12 <pool> <device>
 
-To activate compression
+To activate compression (see section <<zfs_compression,Compression in ZFS>>):
 
  zfs set compression=lz4 <pool>
 
@@ -433,6 +433,31 @@ change-key` commands and the `Encryption` section from `man zfs` for more
 details and advanced usage.
 
 
+[[zfs_compression]]
+Compression in ZFS
+~~~~~~~~~~~~~~~~~~
+
+You can enable compression on a ZFS dataset with:
+
+ zfs set compression=<algorithm> <dataset>
+
+The `lz4` algorithm is recommended, since it is highly performant. Other
+algorithms like `lzjb` and `gzip-N`, where `N` is an integer from `1`
+(fastest) to `9` (best compression ratio), are also available.
+
+Once enabled, ZFS compresses all *new* blocks before writing them (and
+decompresses them after reading). If your CPU can compress/decompress the
+data as quickly as it comes in, having compression enabled can even increase
+I/O performance. Data that existed before compression was enabled will not
+be compressed automatically.
+
+You can disable compression at any time with:
+
+ zfs set compression=off <dataset>
+
+Again, only new blocks will be afffected by this change.
+
+
 ZFS Special Device
 ~~~~~~~~~~~~~~~~~~
 
-- 
2.20.1