8 laptop HDDs getting low speeds

[Johnnnnnnnnnny]

Hi,
I have finished my first FreeNas build in order to recycle some old laptop HDDs and would love some advice tunning the performance.

My specs:

• ASUS B450m TUF
• FreeNAS-11.2-U8
• Ryzen 2200g @2.8 Ghz
• 16GB DDR4 @ 3200 Mhz
• Dell Perc H310 flashed to IT firmware
• Intel X550 T2
• Boot SSD 128GB
• Storage 8 x 500GB laptop HDD on HBA 310 in RAID-Z array
• Cache 2 x Sata 128GB SSDs Silicon Power connected to motherboard SATA ports.

I`m getting around 200MB/s sequencial reads from the HDDs and around 360MB/s when the files are cached.
Writes begin at 800MB/s but after couple of seconds they drop to around 180MB/s

I was hoping for around double the speeds when I did my research so I would love to find where my bottleneck is.

I know it`s not the network because I was getting around 800MB/s reads and writes when I tested my cache drives in a striped pool.
I also know that I was getting around 130MB/s from those 8 HDDs in RAID-Z2 array and around 200MB/s in RAID-Z array
Cpu utilization goes up to 22% when copiing and memory usage is always around 15GB.
How would I proceed to diagnose whhere the bottleneck is?
Many thanks.

 

[JaimieV]

You're using a single RAIDZ? That'll be the limitation. It'll be running at pretty much the speed of one drive, any write has to wait for the slowest drive to complete before moving on to the next write.

Go to a mirrored pairs config, that'll get you the most speed and most iops. Take a read of these two for the best way to shape your pool:

https://constantin.glez.de/2010/06/04/a-closer-look-zfs-vdevs-and-performance

ZFS Raidz Performance, Capacity and Integrity Comparison @ Calomel.org

(I'm using 9 drives in a pool made of three RAIDZ1 and get ~900meg/sec over 10gigE)

Your two "cache" SSDs may not be helping you. L2ARC is something I have skipped entirely as I have lots of RAM, but there are black arts to it and it probably doesn't do what you think it does. Info here:

Use cases for L2ARC

I’m having a lively discussion with @microserf elsewhere in this forum, and we’re hijacking a question about “what should be my first motherboard”. I’m taking this discussion here. The two positions: I can’t think of a home / enthusiast use case that would ever justify an L2ARC. Certainly not...

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