Slow HDD

[dawuki]

Hi yesterday I will getting write speeds of about 50MiB
View attachment 64159
However, today it has been really slow only achieving around 10Mib

Is this normal or did I do something wrong. This occurred after i turned it off for the night.

ASUS Z170-A
Intel i7-6700 3.4Ghz
4tb Seagate Barracuda, 16gb Generic USB (Boot)
INTEL I219v gigabit lan

Thanks for you help in advance!
Dawuki

 

[LarsR]

If this ST4000DM004 is the model Number of the Seagate Baracuda Drive then it's an smr drive that dont work with truenas/zfs.
What you want are CMR Drives like the Seagate Ironwolf, Ironwolf pro, Exos or Western Digital Red Pro series.

 

[dawuki]

How come it was at around 50MiB and now it has dropped to 10MiB?

 

[sretalla]

How come it was at around 50MiB and now it has dropped to 10MiB?

SMR (more specifically DM-SMR) disks have a temporary storage area on the drive which isn't SMR. As data is copied to the disk, it will fill that area, then later (at a time decided by the drive) will move the data off to the SMR area (which is a slow operation).

During the move to the SMR area, the drive is busy, but will not show that to the OS.

If you continue to copy data to the drive until the non-SMR area fills completely, there's no other choice than for the drive to move some of that data into the SMR area to make room for new data... of course, this makes the drive busy doing 2 different kinds of operations (one copying new data to the non-SMR area and another taking data out of that area and putting it into the SMR area).

I suspect what you experience here is the difference in speed between writing data to the (not yet full) non-SMR area of the drive and then subsequently to the completely full non-SMR area (involving the additional work for the drive), slowing it all down.

I can't look at the internal actions on your drive to confirm that, but it makes sense to me.