Are there any good reason not to use ZFS Compression ?

Are there any good reason not to use ZFS Compression,
I got a quad core xeon and 12 GB ram I can se I get 2-3 GB off af BLU-RAY iso files.
that will be compres are bluray iso and dvd iso and tv show I rip to mkv it will be stream to my popcorn hour can it give som problems when it compres will resilver off the raidz take longer when it are compres ?

(this is what i think, i'm not a guru)
It doesn't really matter to raid if your data is compressed or not, it's just bits. (when resilvering)
The only diffirence it makes is the cpu usage -> slowdown when compressing & decompressing.
I think the only way to find out if it will work out for you is to give it a go

I would bet money there is no way you get 1-2 GiB compressed away from a blu-ray-video. Unless there is some metadata/additional stuff on a bluray that is compressible...

I would not go that road, it loads your cpu with hardcore compressing-load on data that has been already compressed by the most advanced video-codecs...

hotzen said:

I would bet money there is no way you get 1-2 GiB compressed away from a blu-ray-video. Unless there is some metadata/additional stuff on a bluray that is compressible...

Click to expand...

Well, he did say ISO, just a disk image, so thats uncompressed afaik. You could compress a few gigs off a huge ISO i think..

so I just make a new test lzjb it only give me 1GB off 300 blu-ray iso 33GB whit out Compression and whit lzjb 32GB whit Gzip-9 30GB and the cpu load are low when streming the gzip

Depends what is on the ISO. Generally stuff on opticals is compressed anyway, like movies or data files. The only thing compressible would be text files and binaries (.exe/.dll).

Compression is sexy on folders with text-only documents. So 20MB is compressed to 90 kilobytes; that sort of thing. For mixed data the lowest compression could shave off a few percent. Generally, it is not worth the performance loss and if you want a few gigabytes more space then buy an extra disk. That allows you to run without slowing technologies like compression and de-duplication. Those should be used only when they make sense; on data that could use it.

ok so the drawbacks are biger in the benefit thx for the help

Yes, typically only enable compression on specific datasets (directories) that you expect to be able to compress fairly. On large bulk data that is usually compressed already, i wouldn't enable ZFS compression for performance reasons.