compression and atime

[Mike83]

Hi

Does anyone know what these are for? I have checked the wiki page, I think I'm getting an idea about compression, its for if you are storing uncompressed things, it mentions a performance gain though? Is that the write speed to the server? How come it doesn't show the file as compressed when you put a uncompressed file onto a server? Is it doing it in the background? So it will show a 600mb file on your server, but really only be taking up 400mb?

Do most people use compression? I get about 42mb/s using lzjb and 82mb/s using inherit

Also I can't find much info on atime, except "controls whether the access time for files is updated when they are read; setting this property Off avoids producing write traffic when reading files and can result in significant performance gains, though it might confuse mailers and other utilities such as make"
I am just using this as a homeserver, I don't know if I will use mailers or make (whatever they may be!) what settings do most people use?

Thanks

 

[Joshua Parker Ruehlig]

Hi

Does anyone know what these are for? I have checked the wiki page, I think I'm getting an idea about compression, its for if you are storing uncompressed things, it mentions a performance gain though? Is that the write speed to the server? How come it doesn't show the file as compressed when you put a uncompressed file onto a server? Is it doing it in the background? So it will show a 600mb file on your server, but really only be taking up 400mb?

Do most people use compression? I get about 42mb/s using lzjb and 82mb/s using inherit

Also I can't find much info on atime, except "controls whether the access time for files is updated when they are read; setting this property Off avoids producing write traffic when reading files and can result in significant performance gains, though it might confuse mailers and other utilities such as make"
I am just using this as a homeserver, I don't know if I will use mailers or make (whatever they may be!) what settings do most people use?

Thanks

I use compression on datasets that hold uncompressed files that would take less space with compression, like a dataset with lots of documents / text files. It increases cpu use (i wouldn't use it with very low power cpus), but alot could possibly increase read/write speed because less is read/written from/to disk. Yes, all the compression is in the background. It also saves space, so that may be helpful.

As for atime, I disable it on all my datasets except for my plugins jail dataset (incase the jail has files it wants to track last read time).
What atime does is log to disk the last time a file was read, this could really decrease performance in some cases. Alot of people use noatime (disable atime) on linux / freebsd systems on ssd (to increase lifetime) and harddrives (to lower the random writes needed). I really recommend disabling atime on any data you don't closely need to monitor, unless you really need to know the last time files were opened, not just changed.