SMR Disk performance - TS453D

Questions about SNMP, Power, System, Logs, disk, & RAID.
vskal
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Joined: Sun Jul 05, 2020 4:57 pm

Re: SMR Disk performance - TS453D

Post by vskal » Tue Jul 14, 2020 5:56 am

I have been offered to RMA with WD Red Pro 4TB Model: WD4003FFBX
Even though an overkill for my NAS I think it is a great offer and think I should take it.
Just the 5 years warranty is so great !

vskal
Starting out
Posts: 27
Joined: Sun Jul 05, 2020 4:57 pm

Re: SMR Disk performance - TS453D

Post by vskal » Fri Jul 17, 2020 8:11 pm

Replacement HDD's have arrived from WD and array is rebuilding.

The part number for both is WD4003FFBX but the sticker is different as you can see.
InkedIMG_5883_LI.jpg
It doesn't write WD Pro. It also writes "Recertified May2020" and I hope they are not repaired drives.

Registered both with WD and I will check if the 5 year warranty is valid once I return the old disks.
At least now I have CMR disks. The old SMR is on the left while the right disks, with the thicker platter space, is the new CMR.
IMG_5885.jpg
IMG_5886.jpg
When the array rebuild completes, I will test and post the HDD performance test.
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vskal
Starting out
Posts: 27
Joined: Sun Jul 05, 2020 4:57 pm

Re: SMR Disk performance - TS453D

Post by vskal » Sun Jul 19, 2020 7:27 am

Test results follow, still trying to understand if the original SMR disks had a performance issue.
Array: RAID 1

SSH Tests
With 2x WD Red 4TB (SMR)
Throughput RAID_Throughput Disk Type
23.04 MB/s 245.35 MB/s WDC WD40EFAX-68JH4N0
23.11 MB/s 245.35 MB/s WDC WD40EFAX-68JH4N0

With 1x WD Red 4TB SMR & 1x WD RED Pro
237.81 MB/s 247.49 MB/s WDC WD4003FFBX-68MU3N0
20.42 MB/s 247.49 MB/s WDC WD40EFAX-68JH4N0

With 2x WD RED Pro
237.56 MB/s 296.25 MB/s WDC WD4003FFBX-68MU3N0
243.99 MB/s 296.25 MB/s WDC WD4003FFBX-68MU3N0

Both WD Red SMR disks had a very low (23 MB/s) throughput.
When the WD Red Pro were introduced in the array, the qcli test showed a tenfold throughput increase from the Pro disk.
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In parallel, together with the above SSH tests, I was using QNAP’s Disk Performance Test from the Storage & Snapshots application -> Disks/VJBOD
QNAP Application Disks/VJBOD Performance Test
With 2x WD Red 4TB (SMR)
Disk 1 - Sequential Read: 383,83 MB/s IOPS Read: 327
Disk 2 - Sequential Read: 158,87 MB/s IOPS Read: 106

With 1x WD Red 4TB SMR & 1x WD RED Pro
Disk 1 - Sequential Read: 241,41 MB/s IOPS Read: 187 - WD Red PRO
Disk 2 - Sequential Read: 173,20, MB/s IOPS Read: 116 - WD Red SMR

With 2x WD RED Pro
Disk 1 - Sequential Read: 214,68 MB/s IOPS Read: 189
Disk 2 - Sequential Read: 240,74 MB/s IOPS Read: 187

The first test numbers for Disk 1 were way off the realistic potential of the HDD and they surely do not correlate with its “exceptional” performance in the SSH test above !
Maybe the SMR controller and cache are the cause of this inaccuracy in the results.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Finally, some observed differences between Red’s and Red Pro’s
Array Build Time (RAID 1)
9,5 hours - reading from Disk 1 (WD Red) and writing to Disk 2 (WD Red PRO) – Disk Throughput 88,1 MB/s
7 hours - reading from Disk 2 (WD Red PRO) and writing to Disk 2 (WD Red PRO) – Disk Throughput 154,9 MB/s


SMART reporting Temperature
WD Red 4TB (SMR): 39 - 44 0C
WD Red PRO: 44 -49 0C
Red Pro disks run significantly hotter!

vskal
Starting out
Posts: 27
Joined: Sun Jul 05, 2020 4:57 pm

Re: SMR Disk performance - TS453D

Post by vskal » Tue Jul 21, 2020 6:50 pm

Finally, I safely erased the two red SMR disks, preparing them for return to WD.
I thought why not do a final test?
These disks are 3 & 4 and are not in a RAID array anymore.

At last, the WD Red's SMR now seem to show more reasonable results: approximately 180MB/s and 120 IOPS compared to the wrong values of my OP at 383MB/s and 187 IOPS
Screenshot (33).png
[~] # qcli_storage -T force=1
Enclosure Port Sys_Name Throughput RAID RAID_Type RAID_Throughput Pool
NAS_HOST 1 /dev/sdc 239.37 MB/s /dev/md1 RAID 1 299.36 MB/s 1
NAS_HOST 2 /dev/sda 242.33 MB/s /dev/md1 RAID 1 299.36 MB/s 1
NAS_HOST 3 /dev/sdb 144.82 MB/s -- -- -- --
NAS_HOST 4 /dev/sdd 143.37 MB/s -- -- -- --

Also, in the SSH test, the throughput now shows a more reasonable value of 140MB/s compared to 22MB/s of my OP tests.

So, not being in RAID or erasing the drives, or changing their position seems to have corrected the problem and tests now output normal values.

I am curious if the SMR cache and device managed driver are responsible for the results or if it were my disks actually under-performing?
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