HDD I/O permament writes, what causes it?

Guys,

I see in reports that the HDDs are constantly writing all time, also hear HDDs are working.
I have disabled all applications and also blocked inbound firewall but anyway it still writes something non stop.


Any ideas?

ok, partially it was NFS service.

Anyway, seeing where this activity is going (I mean, file system level) would be just great.

If that HDD Pool was the First one you’ve created it’s most likely the system Dataset which writes log Data to the pool. You can Switch the system Dataset to your Boot ssd

omg, yes my primary data pool is used by system. Can you tell how to move it?

But the ix-applications dataset and all other datasets used by application I have already installed are located on this disk, do you mean moving all these data to ssd?

ok I found this:

As I understand from the manual page this dataset is used by system to store cache, logs and user permissions data, right?

So it’s ok to move this dataset to ssd and my current app installations on my HDD pool will be intact?

Yes, it’s perfectly save to move the system Dataset off the HDD Pool and to either a SSD datapool or your boot drive

ok, I have 512gb ssd, 2gb swap size is default value, I can’t find this in manuals, is it enough with 16gb of ram, or increase it to say 16gb or more, how do you think?

Move to SSD, but there is something still writing every other second to the primary pool…

@Lev While my crystal ball has yet to be fixed, can you tell us what version of TrueNAS you are running? Based on the screen posts I have to assume it at least one of the SCALE versions.

So you moved the system dataset. Have you disabled all services? Do you have any jails/vms and have you disabled those?

Did you unplug the Ethernet cable? If it stops then you know you had some sort of traffic. It could be as simple as a Windoze computer just verifying the share is still available.

Now for the part I hope it isn’t… What are the manufacturer and model numbers of your drives? Why do I ask? Is one or more SMR drives? After you put data on them they may just put data wherever they can but it is not optimized for an SMR drive, so when the drive is not busy, it starts rewriting your data to organize it properly.

hey thanks for help,

Truenas: Dragonfish-24.04.2
SSD: Samsung 870 EVO
HDDs: 2x WD120EFBX (primary pool), 2x WD80EFAX (secondary pool)

After LarsR’s suggestion, I moved system dataset to SSD and this helped a bit, but besides logs and cache files, something is still there, continuously writing to my primary pool, secondary pool is dead silent, all services/apps stopped. I didn’t physically detached ethernet cable but blocked all incoming traffic to it.

I can see constant activity in the reporting page that it’s writing but I can’t determine what and where it exactly writes data.

I moved the “Applications” to a different pool, and it moved the disk writes to that drive.

So to me, it seems that Applications is responsible for the constant small writes (even when no Applications are running).

From TrueNAS SCALE Constant Disk Writes

Seems like I’m not alone.

Why should application write data while it’s disabled?

Kubernetes.

May be better when it’s based on Docker in Electric Eel.

If you’re not using the apps, then unset the apps pool