Slow write performance to a single disk pool

maoravni

Cadet
Joined
Oct 31, 2018
Messages
4
I'm a noob to TrueNAS. I have a NAS running OMV and I've purchased new disks for it. I'm considering upgrading to TrueNAS, but first, I need to back up my data.

I have installed one drive on a Xeon machine running ESXi, installed TrueNAS Core on a VM and directly attached the new drive to the VM.

The purpose of the setup is simple: backup the data on the NAS and fiddle around with TrueNAS and get to know it.

The network is simple 1GB ethernet.

When backing up data to the drive I see write rates of ~30MB/s. The disk is showing as 100% busy.

When writing data after idling the network is saturated for a few moments and then goes back to the same rate.

I have verified that this is related to the amount of RAM available to the OS by changing the VM settings. Setting a different number of CPUs doesn't affect the speed either.

It's probably something I'm missing in my (non)-understanding of ZFS. Can someone please enlighten me?

Should I go through the trouble of booting from a USB drive and not from ESXi for this task? Will I get better write rates?

And another performance question:
I know the NAS is sub-par, but what's the experience that I should expect from an Atom D525 with 8GB RAM and 5x10TB disks?

TrueNAS will only be a NAS. Nothing else will run on it. The only use for it is the storage of media and important files for redundancy. (I know this is not backup. I backup regularly to a backup provider).
 

maoravni

Cadet
Joined
Oct 31, 2018
Messages
4
Forgot to add some actual hardware:
The server running the VMs is a dual Xeon E5-2620 with 64GB, 16 cores, 32 threads. Can't remember the manufacturer of the motherboard.
The case has 2x3.5 HDD bays so it can't perform as a NAS without HW upgrades.
The server has 2x1GB NICs.
The new disks are 10TB HGST CMR. slightly used.

The pool has compression off and no atime.
Reading from the pool I can saturate the connection.
 
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