(SOLVED) unRAID 6.9.2 - slow Array write speed - high IO-Wait

[Reclaim]

Hi all,

 

i have problems with high IO-Wait Times (30-50%) when writing to the Array directly. Write Speeds at the first 10 Seconds are at 170 MB/s then it drops to < 10 MB/s. Sometimes it also hits 0 Byte/s for a couple Minutes.

The Problems are on SMB, on Terminal, on VM´s, on Mover and on Docker Containers.

Reads from the Array are fine, no IO-Wait.

Writes/Reads from Cache is also fine.

 

I tried so far:

Added a new Disk to the Array - PreClear Speeds at >20% was also very low.

New SATA-Cables

BIOS Upgrade

Disk Shares instead of User Shares

reconstruct write

 

On the Screenshots you can see the Speeds while copying files from the Unassigned Device to the Array. Also I took a Screenshot from "top" and from the PreClear report.

 

I hope you can help me with this.

Thanks!

 

Setup:

Gigabyte Technology Co., Ltd. W480M VISION W

American Megatrends Inc., Version F20
BIOS dated: Mon 19 Apr 2021

 

Intel(R) Core(TM) i5-10400 CPU

32 GB RAM

3x ST8000DM004 in Array (1 Parity, 2 Disks)

2x CT1000MX500SSD1 in Cache

1x ST2000LM007 as Unassigned Device

 

 

 

 

 

Edited July 20, 2021 by Reclaim

[JorgeB]

27 minutes ago, Reclaim said:

ST8000DM004

These are SMR and write performance can downgrade, sometimes a lot.

[Reclaim]

Well, I didn´t know that this are SMR Drives.

Thank you for the hint.

 

But is it normal that the write Performance is this bad? I mean <10MB/s. Is it because I encrypt the Drives?

What you Guys recommend me, swap all Drives out?

[JorgeB]

Write performance with SMR drives can downgrade by a little or a lot, some models behave better than others, that one appears to be one of the worst, and not consistent, i.e., one disk can perform OK and another same of model can perform extremely bad.

[Reclaim]

Thanks, i will look for new HDD´s.