[ZFS write speed issue (array disk, no parity) on 6.12.0-rc6]

On 9/19/2023 at 8:38 AM, JorgeB said:

If the drive is really in a pool, not the array,  it can't be the same problem, since the md driver is not used, maybe it's an SMR drive? If not suggest creating a new thread in the general support forum and post the diagnostics. 

 

I was led to believe that the md driver was used when not setting up exclusive access to for the share. But I guess that I was mistaken. 

 

It's not SMR, but a slow 2.5" drive only just capable of Gb transfer rates. 

 

I will do some more tests with and without zfs. I will probably let zfs go anyway for now as the drives with zfs keep spinning up. I use the B460 chipsets SATA controllers.

[ZFS write speed issue (array disk, no parity) on 6.12.0-rc6]

On 9/3/2023 at 9:58 PM, JorgeB said:

It works fine with a single device pool, I believe the Unraid driver (md driver) needs some tuning to perform better with zfs.

 

I think that I see the same problem on a single pool drive, I use a 500GB 7200rpm 2.5" disk for always on services as I have a cctv software that's rumored to chew up SSD drives.

 

The symptoms are one or two pegged cores on the dashboard but nothing out of the ordinary is shown in htop. The transfer runs at full GB speed, 112-113MB/s. But stopps drops to 0 once in a while.

 

The same transfer to a nvme drive use much less CPU.

 

For some reason I can't get iotop or the stats plugin to show any transfer speeds.

 

I have not done any zfs tuning yet. I have never had to do that on a modern computer with GB ethernet but I have seen erratic performance with ZFS when using too old hardware for testing.