Is it normal for scrub to increase swap usage?

[junior466]

As the title says, I've noticed that exactly the time a scrub starts, swap usage increases and stays there until a reboot.
Example:

I've been doing some research on an issue I've been having with my system throwing the error freenas swap_pager_getswapspace: failed so research lead me here.
I am trying to find out if eventually scrubs will cause swap to increase to a point where any extreme load in my system will cause swap space to be used completely causing this error?

Just brainstorming since I am yet to find the reason for the error. As I described in the thread linked above, no jails or plugins. Just serving simple SMB/NFS shares.

Build FreeNAS-11.1-U6
Platform Intel(R) Xeon(R) CPU E5-2403 0 @ 1.80GHz
Memory 16GB

 

[Chris Moore]

You must be running a VM or something that is using memory. It is not JUST the scrub that caused the memory usage.
Also, please provide the rest of your hardware description per the guide here:

https://forums.freenas.org/index.php?threads/updated-forum-rules-12-5-18.45124/

 

[junior466]

Not running jails or VMs.



My hardware:

• PERC H310 Adapter RAID Controller (IT mode)
• Intel Xeon E5-2403 1.80GHz, 10 M Cache, 6.4GT/s QPI, No Turbo , 4C, 80W
• (2X) 8GB RDIMM, 1600MT/s, Low Volt, Dual Rank, x4 Data Width ECC

Mirror pool two vdevs.

 

[toadman]

Happened to me before. i.e. I saw some swapping I didn't think should be happening. See the following for some sysctls that helped the ability of the system to respond to memory pressure. A few of us have had success with these settings. Took a bit of time to tune to the right value. Haven't had a swap issue since. (And yes, issue occurred on the 11.1.x versions as well. Also resolved there.)

https://forums.freenas.org/index.php?threads/swap-with-9-10.42749/page-5