Bug 139336

Summary: [request] ZFS documentation suggestion
Product: Documentation Reporter: Bernard Steiner <zdbs>
Component: Books & ArticlesAssignee: Allan Jude <allanjude>
Status: Closed FIXED    
Severity: Affects Only Me    
Priority: Normal    
Version: Latest   
Hardware: Any   
OS: Any   

Description Bernard Steiner 2009-10-03 15:20:01 UTC 
In the light of possible file system compression as included in (e.g.) ZFS,
may I request that the accompanying how-to to (e.g.) ZFS should mention
whether or not it is advisable to have compression turned on for directories
containing executables and/or shared libraries. (I have a hunch that it is
not..)

If it turns out that this is not advisable, may I suggest that static/
archive versions of libraries (.a) be installed and linked from a directory
different to that of the corresponding dynamic/shared (.so) libraries.
Comment 1 Gavin Atkinson freebsd_committer freebsd_triage 2009-10-03 17:05:16 UTC 
Responsible Changed
From-To: freebsd-bugs->freebsd-doc

I think this is probably best as a doc PR
Comment 2 fjwcash 2011-11-22 22:40:59 UTC 
Using ZFS compression on filesystems with binaries, executables, shared
libraries, and/or static libraries works without issues.  Been using it
here since ZFSv6 with both lzjb and gzip-9 compression without any issues.
 And have also been using it with deduplication enabled without issues.

FreeBSD 7.2 through to 9.0-RC2 (and all versions in between).
ZFSv6 through ZFSv28 (and all versions in between).

-- 
Freddie Cash
fjwcash@gmail.com
Comment 3 Allan Jude freebsd_committer freebsd_triage 2014-05-23 16:05:01 UTC 
ZFS compression is completely transparent, so the OS and applications
running on top of it are unaware of it. It is safe to compress any files
on your system.

With the new LZ4 option in ZFS v5000 (FreeBSD 9.2, 8.4 and 10.0 or
later), the overhead of the compression is much smaller. In addition to
being able to compress at 500mb/s/core and decompress at 1500mb/s/core
on a low end i3 laptop processor, LZ4 also has an 'early abort' feature,
where if the compression ratio of the block is less than 12.5% after the
first ms of attempting to compress it, it aborts and writes the block
uncompressed. This means it will not waste a lot of CPU time trying to
compress already compressed files like .tar.gz or .mp3

This is documented here:
http://www.allanjude.com/zfs_handbook/zfs-term.html#zfs-term-compression

And should be committed to the handbook shortly.

-- 
Allan Jude
Comment 4 Allan Jude freebsd_committer freebsd_triage 2014-05-23 16:29:50 UTC 
State Changed
From-To: open->closed

take and close. The question has been answered and the new handbook  
chapter further clarifies this for the future
Comment 5 Allan Jude freebsd_committer freebsd_triage 2014-05-23 16:29:50 UTC 
Responsible Changed
From-To: freebsd-doc->allanjude

take and close. The question has been answered and the new handbook 
chapter further clarifies this for the future