Why is TrueNAS writing 9GB/day to my boot drive?

TrueNAS General
1

After looking into another issue yesterday (I was hearing a constant “clicking” as if the HDD head was doing something despite no disk activity. That’s now gone, on it’s own…) but through that whole process I became aware that my boot drive nvme was getting CONSTANT writes:

https://imgur.com/a/xuimhyb

(also includes hopefully some other relevant screenshots. Can grab additional data if helpful!)

Averaging basically 110KB/s, that’s 9GB+ a day? Of what!?

Setup overview:

  • TrueNAS v25.10.1 on a Terra Master F4-425 Plus

  • TrueNAS installed on to 16gb nvme (this is getting the constant writes)

  • 2x 16TB drives in a mirror (shucked seagate expansion drives)

  • Pretty fresh, simple, barebones install.

    • No apps, no VMs. Using SMB (though no active connection)

You can see the writing has been constant, even while I’ve been sleeping. CPU usage is similarly not “idling” (nothing happening or earlier 7am while I’m sleeping!) and randomly spiking up for a moment. But you can see my mirrored 16TB drives are getting zero activity, as expected. Not in screenshots, but network is also getting basically zero traffic - as expected.

I’ve not yet set up any data protection, snapshot, or other automated tasks.

Looking online I do see a bunch of posts over the years about similar constant write issues but mostly I wasn’t able to find any answer or explanation, and I think at least some of those were NOT on the system/boot drive.

2

Do you have the boot-pool set for your System Dataset Pool? System, Advanced Setting then look for Storage

3

On which pool is the system dataset?

System: Advanced Settings: Storage

1 Like
4

Truenas is very chatty. Dont ask me what exactly is written that amounts to 10GB/ day.

But even a cheap NVMe with 40TBW will last almost a decade like that. How many TBW does your 16GB drive have ?

5

System Dataset Pool: Storage

Resilvering At Higher Priority: Never

6

It’s the cheap intel optane M10 16gb drives. Looks like datasheet is 365. Which, yeah, is tons. I guess from that aspect I’m not as worried. Plus it’s just the boot drive, which was under $10 and could easily be replaced even temporarily. Would still love to know if this is “normal” or downright fully expected, vs maybe I should be making some adjustments - or maybe something is actually WRONG

7

Its normal. Thats why its not recommended anymore to use a USB stick as a boot disc.