Explanation of Disk Tunables

[Taddeusz]

I've been messing around with my tunables lately. I had them modified them to the recommended settings for larger arrays to:

md_num_stripes: 4096
md_sync_window: 2048
md_sync_thresh: 2000

I decided to start messing with them because I've noticed that when I'm moving around large files from my array to my cache it appears to burst reading and writing. I have 9 drives (8+parity) and 16GB of RAM so I decided to doubled md_num_stripes to 8192 (I figure that it's using 256MB for stripes now). I performed the same file move and it's now continuously reading from the array while writing to the cache.

 

I don't know if I should also modify the sync settings? There doesn't seem to be a very good description of the tunables. And I know there's the tunables tester but it's kind of old now.

 

I do plan on adding another 16GB of RAM so memory shouldn't be a problem. Just wondering if I can more easily determine the optimal settings for my Unraid server?

[JorgeB]

11 hours ago, Taddeusz said:

There doesn't seem to be a very good description of the tunables.

Original tunables:

https://lime-technology.com/forums/topic/4473-unraid-server-release-45-beta8-available/?do=findComment&comment=41691

 

Sync thresh

https://lime-technology.com/forums/topic/42369-unraid-server-release-614-available/?do=findComment&comment=416597