After growing pool drives continue to do active writes, is there a FreeNAS reason?

[SmoothRunnings]

FreeNAS v11.1 U6
Dell R510
Dual 6core CPUs
64GB of RAM
Perc H200 IT Mode controller
14 x Seagate Constellation.2 2.5" 7200RPM SAS drives (ST910000640SS)
Pool configuration 14 drives in a raidz2

The drive has been resilvered, when I do a zpool status nothing appears to be running (scrub etc) but when I look at the Disk logs in Reporting the drives are being constantly written to. The drives activity lights on the server are on. Not sure why this is happening, does FreeNAS do something else in the background?

Here is a screen shot of the Disk log showing I/O on the first 3 drives, its the same for the remainder.


Thanks

 

[kdragon75]

Do you have any jails or VMs?

 

[SmoothRunnings]

Do you have any jails or VMs?

Nope. I use my FreeNAS server as a SAN box. It connects directly to my ESXi Host via Intel D520 10Gbe fiber over iSCSI.

 

[Chris Moore]

Here is a screen shot of the Disk log showing I/O on the first 3 drives, its the same for the remainder.

https://imgur.com/UAw1RUX

Please upload images directly to the forum.

No need to put them someplace else. Just copy and paste, that is what I did.

That activity is in the "k-Byte" range, so it isn't as much as you might think. The chart automatically scales.
FreeNAS, by default, uses the storage pool as the place to write the system dataset, which holds data that is constantly accessed. If you want your main storage pool to be quiet, you have to put your system dataset, syslog and reporting database someplace else. I have a mirrored pair of drives in my system that is just for that and they are typically in the .1 to .2 M-Byte range, with spikes to 1 MB, because the writes are to just two drives instead of spread across the entire pool. Even for an idle system, this is not unusual.

 

[Chris Moore]

PS. It is this kind of activity that would quickly kill a USB stick back in the day, before they started automatically moving the system dataset to the storage pool.

 

[SmoothRunnings]

If you want your main storage pool to be quiet, you have to put your system dataset, syslog and reporting database someplace else. I have a mirrored pair of drives in my system that is just for that and they are typically in the .1 to .2 M-Byte range, with spikes to 1 MB, because the writes are to just two drives instead of spread across the entire pool. Even for an idle system, this is not unusual.

Sorry about the image, lol.
I was used to Reddit. :)

Is the syslog and reporting database related to the ZIL and L2RAC?

Thanks

 

[Chris Moore]

Is the syslog and reporting database related to the ZIL and L2RAC?

No.
The ZIL (ZFS Intent Log) is another thing that writes to the storage pool, but you don't get to choose about that, unless you get a SLOG (Separate LOG Device) which is normally a very fast (PCIe / NVMe) SSD of some sort and you only need that if you are doing sync writes.
The L2ARC doesn't exist, unless you install a separate device for it also. You have ARC (Adaptive Replacement Cache) in RAM, but not L2 (Level 2) ARC.
L2ARC is also only useful in certain circumstances and it is usually more benefit to just add RAM for regular ARC which is super fast.