Slow write performance

[chrisnavigation]

Hi all,

Building a TrueNAS CORE for the first time. I've got 8 x 16TB drives setup in one Pool and single VDEV setup as Z2. The server is a Supermicro 12 bay 2U server with onboard network card 1gbps.

To initially test the the disk performance, I've provisioned an Ubuntu virtual machine in Bhyve on the TrueNAS, and have installed KDiskMark on the VM to test the disk read and write performance.

What could be causing the write speeds to be this slow?

Thanks!

 

[Arwen]

Please supply the full hardware configuration, and how the disks are wired up to the server, per forum rules.

 

[Davvo]

Please read the following resources:

Introduction to ZFS

This is a short introduction to ZFS. It is really only intended to convey the bare minimum knowledge needed to start diving into ZFS and is in no way meant to cut Michael W. Lucas' and Allan Jude's book income. It is a bit of a spiritual...

www.truenas.com

ZFS Storage Pool Layout

This resource was originally created by user: @Davvo on the TrueNAS Community Forums Archive. https://www.truenas.com/community/resources/zfs-storage-pool-layout.201/download [1] This amazing document, created by iXsystems in February 2022 as a “White Paper”, cleanly explains how to qualify...

www.truenas.com

Resource - The path to success for block storage

ZFS does two different things very well. One is storage of large sequentially-written files, such as archives, logs, or data files, where the file does not have the middle bits modified after creation. This is optimal for RAIDZ. It's what most...

www.truenas.com

Some insights into SLOG/ZIL with ZFS on FreeNAS

What is the ZIL? POSIX provides a facility for the system or an application to make sure that data requested to be written is actually committed to stable storage: a synchronous write request. Upon completion of a sync write request, the underlying filesystem is supposed to guarantee that a...

www.truenas.com

Could be pool layout (mirror is best for VMs) and the testing being made in a VM that doesn't have access to the full resources of your system, maybe even you using syncwrties without a SLOG. Just educated guesses since we don't have your hardware specs.