SATA WD Gold 20TB - WD203KRYZ transfer read speed very slow.

Unfortunately WD support is not available or rejected my posting.
Expensive drive with read transfer speed below 1 MB/s is useless.
Any ideas if it's a drive design fault or software issue?

WD Gold 20TB - WD203KRYZ-01CMFB0.Windows 11 Pro 25H2.
Formatted NTFS single volume Basic Data Partition.

When attempting to create backup of 1-2 GB files by copying to other drive, then reading speed appears to be as low as 0.1-5 MB/s, with some peaks up to 100 MB/s.
Windows 11 performance reports 100% drive activity, when there are different target drives receiving only small percent of this activity.
Testing:
1. Copying older files from this same drive - transfer speed 100-150 MB/s
2. Source drive WDC WD40EFAX-68JH4N1 same content - transfer speed 100-150 MB/s.

80% of 1-2 GB video clips stored during disk installation on 2025 and 20% later.
Now reading of earlier files happens up to 150 MB/s but later files transfer speed varies between 0.1- 10 Mbps with rare 100 MB/s peaks.

My first assumption was disk fragmentation but Windows 11 "defrag app" reports "0" due to weekly automatic defragmentation.

Drive installed on October 2025. Drive is Bitlocker encrypted due to company policies.
Now there is left about 300 GB of spare space on this drive.


WD Gold 20TB WD203KRYZ-01CMFB0 : 20000.5 GB

----------------------------------------------------------------------------
CrystalDiskInfo 9.2.3 (C) 2008-2024
----------------------------------------------------------------------------

OS : Windows 11 Pro 25H2 [10.0 Build 26200] (x64)
Date : 2026/10/30 19:06:28

----------------------------------------------------------------------------
(03) WDC WD203KRYZ-01CMFB0
----------------------------------------------------------------------------
Model : WDC WD203KRYZ-01CMFB0
Firmware : 01.01H01
Serial Number : *********
Disk Size : 20000.5 GB (8.4/137.4/20000.5/20000.5)
Buffer Size : Unknown
Queue Depth : 32
# of Sectors : 39063650304
Rotation Rate : 7200 RPM
Interface : Serial ATA
Major Version : ACS-4
Minor Version : ACS-4 published, ANSI INCITS 529-2018
Transfer Mode : SATA/600 | SATA/600
Power On Hours : 10453 hours
Power On Count : 26 count
Temperature : 41 C (105 F)
Health Status : Good
Features : S.M.A.R.T., APM, NCQ, Streaming, GPL
APM Level : 00FEh [OFF]
AAM Level : ----
Drive Letter : G:

-- S.M.A.R.T. --------------------------------------------------------------
ID Cur Wor Thr RawValues(6) Attribute Name
01 100 100 __1 000000000000 Read Error Rate
02 148 148 _54 000000000032 Throughput Performance
03 _83 _83 __1 000701680163 Spin-Up Time
04 _99 _99 __0 000000000202 Start/Stop Count
05 100 100 __1 000000000000 Reallocated Sectors Count
07 _97 _97 __1 000000020000 Seek Error Rate
08 136 136 _20 000000000010 Seek Time Performance
09 _99 _99 __0 0000000028D5 Power-On Hours
0A 100 100 __1 000000000000 Spin Retry Count
0C 100 100 __0 00000000001A Power Cycle Count
16 100 100 _25 000000640064 Current Helium Level
C0 100 100 __0 0000000006CD Power-off Retract Count
C1 100 100 __0 0000000006CD Load/Unload Cycle Count
C2 _52 _52 __0 002F00110029 Temperature
C4 100 100 __0 000000000000 Reallocation Event Count
C5 100 100 __0 000000000000 Current Pending Sector Count
C6 100 100 __0 000000000000 Uncorrectable Sector Count
C7 100 100 __0 000000000000 UltraDMA CRC Error Count

-- IDENTIFY_DEVICE ---------------------------------------------------------
0 1 2 3 4 5 6 7 8 9
000: 045A 3FFF C837 0010 0000 0000 003F 0000 0000 0000
010: 5050 4732 4830 584B 2020 2020 2020 2020 2020 2020
020: 0003 0000 0038 3031 2E30 3148 3031 5744 4320 5744
030: 3230 334B 5259 5A2D 3031 434D 4642 3020 2020 2020
040: 2020 2020 2020 2020 2020 2020 2020 8010 4000 2F00
050: 4000 0200 0200 0007 3FFF 0010 003F FC10 00FB 5910
060: FFFF 0FFF 0000 0007 0003 0078 0078 0078 0078 0D08
070: 0000 0000 0000 0000 0000 001F 970E 0076 0CDE 0040
080: 0FFC 009C 746B 7D69 4773 7469 BC41 4773 017F 8347
090: 0000 00FE FFFE 0000 0000 0008 00CA 00F9 2710 0000
100: 0000 1860 0009 0000 00CA 0000 6003 5A87 5000 CCA0
110: E7C1 2129 0000 0000 0000 0000 0000 0000 0000 40DC
120: 40DC 0000 0000 0000 0000 0000 0000 0000 0009 000B
130: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
140: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
150: 0000 0009 5745 0000 0000 0000 0000 0000 0000 0000
160: 0000 0000 0000 0000 0000 0000 0000 0000 0002 0000
170: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
180: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
190: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
200: 0000 0000 0000 0000 0000 0000 003D 0000 0000 4000
210: 0000 0000 0000 0000 0000 0000 0000 1C20 0000 0000
220: 0000 0000 17FF 0000 0000 0000 0000 0000 0000 0000
230: 0000 1860 0009 0000 0008 0000 0000 0000 0000 0000
240: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
250: 0000 0000 0000 0000 0000 F6A5

-- SMART_READ_DATA ---------------------------------------------------------
+0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F
000: 10 00 01 0B 00 64 64 00 00 00 00 00 00 00 02 05
010: 00 94 94 32 00 00 00 00 00 00 03 07 00 53 53 63
020: 01 68 01 07 00 00 04 12 00 63 63 02 02 00 00 00
030: 00 00 05 33 00 64 64 00 00 00 00 00 00 00 07 0B
040: 00 61 61 00 00 02 00 00 00 00 08 05 00 88 88 10
050: 00 00 00 00 00 00 09 12 00 63 63 D5 28 00 00 00
060: 00 00 0A 13 00 64 64 00 00 00 00 00 00 00 0C 32
070: 00 64 64 1A 00 00 00 00 00 00 16 23 00 64 64 64
080: 00 64 00 00 00 00 C0 32 00 64 64 CD 06 00 00 00
090: 00 00 C1 12 00 64 64 CD 06 00 00 00 00 00 C2 02
0A0: 00 34 34 29 00 11 00 2F 00 00 C4 32 00 64 64 00
0B0: 00 00 00 00 00 00 C5 22 00 64 64 00 00 00 00 00
0C0: 00 00 C6 08 00 64 64 00 00 00 00 00 00 00 C7 0A
0D0: 00 64 64 00 00 00 00 00 00 00 00 00 00 00 00 00
0E0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0F0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
160: 00 00 00 00 00 00 00 00 00 00 82 00 65 00 00 5B
170: 03 00 01 00 02 FF 00 CD 07 00 00 00 00 00 00 00
180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1A0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1B0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1C0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1D0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1E0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1F0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 61

-- SMART_READ_THRESHOLD ----------------------------------------------------
+0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F
000: 10 00 01 01 00 00 00 00 00 00 00 00 00 00 02 36
010: 00 00 00 00 00 00 00 00 00 00 03 01 00 00 00 00
020: 00 00 00 00 00 00 04 00 00 00 00 00 00 00 00 00
030: 00 00 05 01 00 00 00 00 00 00 00 00 00 00 07 01
040: 00 00 00 00 00 00 00 00 00 00 08 14 00 00 00 00
050: 00 00 00 00 00 00 09 00 00 00 00 00 00 00 00 00
060: 00 00 0A 01 00 00 00 00 00 00 00 00 00 00 0C 00
070: 00 00 00 00 00 00 00 00 00 00 16 19 00 00 00 00
080: 00 00 00 00 00 00 C0 00 00 00 00 00 00 00 00 00
090: 00 00 C1 00 00 00 00 00 00 00 00 00 00 00 C2 00
0A0: 00 00 00 00 00 00 00 00 00 00 C4 00 00 00 00 00
0B0: 00 00 00 00 00 00 C5 00 00 00 00 00 00 00 00 00
0C0: 00 00 C6 00 00 00 00 00 00 00 00 00 00 00 C7 00
0D0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0E0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0F0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1A0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1B0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1C0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1D0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1E0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
1F0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 DC

@essie


First off, here's ten points for filling out your computer specs.


With a WD RED (5400 rpm) as your source drive, you're seeing about the speed you should, 100-150 MB/s.

The WD203KRYZ is supposed to be a high-performance SATA drive. Helium filled and all that.

Have you run Crystal Disk Mark on it? That might bypass some of the possible oddities of Windows.

I don't use BitLocker, and I don't know what performance penalty it might exact. It's not supposed to matter much with HDDs, given their relatively slow (compared to NVME SSD) transfer rates.

I also have not run a large HDD with 98.5% of its capacity filled. I don't know about Windows 11, but older versions of Windows would not defrag a drive with that little capacity remaining. Yet the drive is reported with 0% fragmentation.

There is 1.5% of free space left, that is far too small.

The figure usually quoted is 10-20% free space for efficient operation of an HDD where contents are changing.
You can read about the reasons for that.

Helmut said:

There is 1.5% of free space left, that is far too small.

The figure usually quoted is 10-20% free space for efficient operation of an HDD where contents are changing.
You can read about the reasons for that.

Click to expand...

Disk is 20TB archive and no application isn't expected to work from this disk. Except sometimes occasional some fail may be played with VLC player and when doubles or obsoletes are found these are deleted. This has left empty clusters 3-5% of total, which has been filled with later file copies from external drives. I considered that such archive disk could be filled 99%. Except I'm not familiar with Windows 11 auto defrag - if there is so little space left, perhaps it may create too much I/O for disk to work properly. Computer doesn't have any 3rd party antivirus.

PS. Contrary to expectations photo maps with file size on 5-10 Mb files copy really fast 60-100 MB/s comapred to bigger files. Looks like there is problem with disk behaviour under Windows 11. When copy stopped, there is no disk I/O activity.

bobkn said:

The WD203KRYZ is supposed to be a high-performance SATA drive. Helium filled and all that.

Have you run Crystal Disk Mark on it? That might bypass some of the possible oddities of Windows.

I don't use BitLocker, and I don't know what performance penalty it might exact. It's not supposed to matter much with HDDs, given their relatively slow (compared to NVME SSD) transfer rates.

I also have not run a large HDD with 98.5% of its capacity filled. I don't know about Windows 11, but older versions of Windows would not defrag a drive with that little capacity remaining. Yet the drive is reported with 0% fragmentation.

Click to expand...

I changed SATA Cable and SATA port but still no change. Crystal Disk Mark random very slow.
Deleted some folders and now there is 150GB of spare space on disk
Bitlocker shouldn't be an issue as used by default on most computers nowadays.
Few month ago this disk has completed similar tasks normally.
What is changed after this may be fragmentation, but Windows 11 reports it 0%.
Copying certain 2GB file takes 40 minutes, while other earlier 2GB file takes only 20 seconds.
Doesn't look like bad sectors but something wrong how Windows handles this disk.