No swap file, all BTRFS drives, how to proceed to have swap mem?

[b0m541]

Hi all,

 

I just realize that my unraid machine does not have swap enabled.

I did not find much information here in the forum.

 

Does unraid by default use a swap file or do I need to enable that manually somewhere?

 

I also found that swap files are not supported on BTRFS on Linux earlier than version 5, which is a pity, because all my drives use BTRFS, also the SSD Cache drives.

 

I never had memory problems, but with recently more docker containers, some of which use a a few hundred MB RAM, I seem to reach a limit, CPU and Storage get very busy when memory fills up. I first thought that this is caused by swap thrashing, and then saw that the machine does not use swap at all....

 

What is the recommended route to go?

 

Put swap on HDD oder SSD? For that I would need to reformat a drive or the cache pool from BTRFS to XFS.

 

Am I overthinking this? Will unraid select the best location and create a swap file when it finds a non-BTRFS formatted drive?

 

If the best way would be to take the cache SSD pool from BTRFS to XFS, what is the recommended strategy to get from a) to b)?

Note: I have empty drives lingering in the array, would be easy to reformat one from BTRFS to XFS, but I guess putting swap on the cache pool is better?