Hi,
gzip/zlib compression is very bad for performance, so it can be interesting for closed indices, but for live data I would not recommend it.
Also, you must know that:
Compression using lz4 is already enabled into indices,
ES/Lucene/Java usually read&write 4k blocks,
-> hence, compression is achieved on 4k blocks. If your filesystem uses 4k blocks and you add FS compression, you will probably have a very small gain, if any. I've tried on ZFS:
Filesystem Size Used Avail Capacity Mounted on
zdata/ES-lz4 1.1T 1.9G 1.1T 0% /zdata/ES-lz4
zdata/ES 1.1T 1.9G 1.1T 0% /zdata/ES
If you are using a larger block size, like 128k, a compressed filesystem does show some benefit:
Filesystem Size Used Avail Capacity Mounted on
zdata/ES-lz4 1.1T 1.1G 1.1T 0% /zdata/ES-lz4 -> compressratio 1.73x
zdata/ES-gzip 1.1T 901M 1.1T 0% /zdata/ES-gzip -> compressratio 2.27x
zdata/ES 1.1T 1.9G 1.1T 0% /zdata/ES
But a file system block larger than 4k is very suboptimal for IO (ES read or write one 4k block -> your FS must read or write a 128k block).
On 21 juil. 2014, at 07:58, horst knete baduncle23@hotmail.de wrote:
Hey guys,
we have mounted an btrfs file system with the compression method "zlib" for
testing purposes on our elasticsearchserver and copied one of the indices
on the btrfs volume, unfortunately it had no success and still got the size
of 50gb
I will further try it with other compression methods and will report here
Am Samstag, 19. Juli 2014 07:21:20 UTC+2 schrieb Otis Gospodnetic:
Hi Horst,
I wouldn't bother with this for the reasons Joerg mentioned, but should
you try it anyway, I'd love to hear your findings/observations.
Otis
Performance Monitoring * Log Analytics * Search Analytics
Solr & Elasticsearch Support * http://sematext.com/
On Wednesday, July 16, 2014 6:56:36 AM UTC-4, horst knete wrote:
Hey Guys,
to save a lot of hard disk space, we are going to use an compression file
system, which allows us transparent compression for the es-indices. (It
seems like es-indices are very good compressable, got up to 65%
compression-rate in some tests).
Currently the indices are laying at a ext4-Linux Filesystem which
unfortunately dont have the transparent compression ability.
Anyone of you got experience with compression file systems like BTRFS or
ZFS/OpenZFS and can tell us if this led to big performance losses?
Thanks for responding
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