Poor write performance with WD RED HDs

[shaun.arundell59]

I have an external disk enclosure connected to my windows server by Thunderbolt 3. The unit has 5 x 3.5 inch disks connected via sata III. It has 2 Iron wolf drives – a 8TB and 10TB and 3 WD red drives 5TB, 8TB and 9 TB.

The read performance on all drives is OK, all are better than 100MBs. The write performance on the Iron wolf drives is good, approx 170 MBs. The write performance on the WD reds is crap, 25MBs – 50 MBs, 70MBs on the 10TB drive. All disk are at between 50% and 90% full with the Iron wolfs over 90%.

I've looked at write caching (all off), fragmentation (0%), which port connected too (makes no difference), all disk have 512 sectors internally, 4K sectors externally.

Any ideas why the WD reds are so crap in this scenario ?

 

[Abula]

WD Reds are usually slower being 5400rpm drives but your sustained seem a little lower than normal for reds.

 

[drescherjm]

Are you writing large files (perhaps a few GB) sequentially?

 

[IdiotInCharge]

Are you writing large files (perhaps a few GB) sequentially?

This, and I'd more suspect some goofiness surrounding the SATA controller used in the controller.

Your average 3.5" spinner can hit 200/200MB/s sequentially without issue.