Slow write speed to ZFS z2 (~700kb /s) and normal read speed (sat 1gbit). Reboot fixing it for a while

[whizzle]

Dear all,

I have tried searching the forum, but could not find a solution to my problem.

I have this strange issue that my write speed drops to very low numbers ~700kb/s. Read speed is still normal ~112mb/s saturating my 1gbit link.
Strangely if i reboot the server. Both write / read speed is normal again at 112mb/s, but after a while (normally a couple of days) issue of slow write speed comes back.

I tried scrubbing the pool couple of times with zero errors
I also did long SMART tests on all drives, all is ok

Any thoughts on what other troubleshooting steps I could take?


My hardware:

• Motherboard make and model: fujitsu d3644-b
• CPU make and model: Pentium G5600
• RAM quantity: 32gb ECC
• Hard drives, quantity, model numbers, and RAID configuration, including boot drives: boot drive is SSD mirror, ZFS pool: 6x 4tb WD RED (EFRX model)
• Hard disk controllers:
• Network cards: onboard

Thanks in advance for taking the time to help guide me.

regards,
whizzle

 

[sretalla]

Version of TrueNAS?

What are you writing? small numbers of big files? large numbers of small files? a mix?

Have you looked at htop while the problem is happening?