Archive-Team
/
zfs
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 103 Wiki Activity

zfs(8): improve document of compression behaviours 

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed by: Allan Jude <allanjude@freebsd.org>
Reviewed-by: bunder2015 <omfgbunder@gmail.com>
Signed-off-by: DHE <git@dehacked.net>
Closes #4660 
Closes #8423
This commit is contained in:
DeHackEd 2019-02-25 14:10:16 -05:00 committed by Brian Behlendorf
parent 8eef997679
commit ba7b05cb25
1 changed files with 13 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
man/man8/zfs.8
View File

@ -1275,6 +1275,19 @@ compression algorithm compresses runs of zeros.
This property can also be referred to by its shortened column name This property can also be referred to by its shortened column name
.Sy compress . .Sy compress .
Changing this property affects only newly-written data. Changing this property affects only newly-written data.
.Pp
When any setting except
.Sy off
is selected, compression will explicitly check for blocks consisting of only
zeroes (the NUL byte). When a zero-filled block is detected, it is stored as
a hole and not compressed using the indicated compression algorithm.
.Pp
Any block being compressed must be no larger than 7/8 of its original size
after compression, otherwise the compression will not be considered worthwhile
and the block saved uncompressed. Note that when the logical block is less than
8 times the disk sector size this effectively reduces the necessary compression
ratio; for example 8k blocks on disks with 4k disk sectors must compress to 1/2
or less of their original size.
.It Xo .It Xo
.Sy context Ns = Ns Sy none Ns | Ns .Sy context Ns = Ns Sy none Ns | Ns
.Em SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level .Em SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level