Starting with Solaris 11.3 ZFS supports lz4 compression. Lets verify the impact to performance if we enable lz4 compression with 2 concrete sample files.
First a zip file containing Solaris 11 SRU Updates and second a simple text logfile.
We disable the ZFS Cache to see the impact of I/O and compression
# zfs set primarycache=metadata v0123_db/source
# zfs set primarycache=metadata compressed/fs
# zfs set primarycache=metadata uncompressed/fs
Test 1 - zipped file
# time cp p25604852_1100_Solaris86-64_1of4.zip /uncompressed
real 1m27.571s
user 0m0.002s
sys 0m4.361s
-bash-4.4$ zfs get compression,compressratio,used uncompressed/fs
NAME PROPERTY VALUE SOURCE
uncompressed/fs compression off inherited from uncompressed
uncompressed/fs compressratio 1.00x -
uncompressed/fs used 1.35G -
# time cp p25604852_1100_Solaris86-64_1of4.zip /compressed
real 1m27.427s
user 0m0.002s
sys 0m4.408s
-bash-4.4$ zfs get compression,compressratio,used compressed/fs
NAME PROPERTY VALUE SOURCE
compressed/fs compression lz4 inherited from compressed
compressed/fs compressratio 1.00x -
compressed/fs used 1.34G -
We see the same duration, no performance loss and because the file is zipped
nearly no space savings.
Test 2 - Log file with Text
# time cp framework.log /uncompressed/
real 0m24.608s
user 0m0.001s
sys 0m1.241s
-bash-4.4$ zfs get compression,compressratio,used uncompressed/fs
NAME PROPERTY VALUE SOURCE
uncompressed/fs compression off inherited from uncompressed
uncompressed/fs compressratio 1.00x -
uncompressed/fs used 390M -
# time cp framework.log /compressed/
real 0m24.495s
user 0m0.001s
sys 0m1.260s
-bash-4.4$ zfs get compression,compressratio,used compressed/fs
NAME PROPERTY VALUE SOURCE
compressed/fs compression lz4 inherited from compressed
compressed/fs compressratio 6.37x -
compressed/fs used 61.4M -
Good compression (6x). We save 330MB of disk space here.
No impact to duration. The SPARC S7 core is fast enough.
And now Read Performance
# time cp /compressed/framework.log /tmp; time cp /uncompressed/framework.log /tmp
real 0m17.415s
user 0m0.001s
sys 0m1.354s
real 0m24.479s
user 0m0.001s
sys 0m1.389s
Better results from compressed filesystem. CPU decompression is faster than doing I/O. Need to read 6x the data from uncompressed zfs filesystem.
Summary
With above samples we don't see negative impact when enabling lz4 compression. If you use compressable text files you save lots of disk space while gaining read performance. We start using lz4 on our ZPOOLs by default now.
