heyitsjel

Not sure with 100% certainty what the issue was, but I did the following and it seems to have resolved my issue: 1) Changed my RAM speed to DDR4 defaults (2400mhz) instead of XMP. 2) Enabled IOMMU groups & other virtualisation settings I thought were already enabled (or at least partially... strange that they seemed to have set themselves back to being disabled). 3) Updated Unassigned Devices plugin. Pre-clear started to act weird at this point; not recognising the attached USB drive details (eg. manufacturer, firmware etc.). Tried moving USB port and rebooting, but made no difference. 4) Uninstalled and then re-installed pre-clear. Issues with drive recognition seem to have fixed themselves. So far I'm now at ~43% post read I'm thinking it's either the RAM or some sort of issue with the previously installed Preclear plugin (eg. corruption).

Okay, So I tried pre-clearing the drive again, and it failed *again* in a different spot: Apr 06 17:10:47 preclear_disk_WCJ2NAHF_10954: Command: /usr/local/emhttp/plugins/preclear.disk/script/preclear_disk.sh --notify 1 --frequency 3 --cycles 1 --no-prompt /dev/sda Apr 06 17:10:47 preclear_disk_WCJ2NAHF_10954: Preclear Disk Version: 1.0.21 Apr 06 17:10:48 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T. info type: default Apr 06 17:10:48 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T. attrs type: default Apr 06 17:10:48 preclear_disk_WCJ2NAHF_10954: Disk size: 5000981077504 Apr 06 17:10:48 preclear_disk_WCJ2NAHF_10954: Disk blocks: 1220942645 Apr 06 17:10:48 preclear_disk_WCJ2NAHF_10954: Blocks (512 bytes): 9767541167 Apr 06 17:10:48 preclear_disk_WCJ2NAHF_10954: Block size: 4096 Apr 06 17:10:48 preclear_disk_WCJ2NAHF_10954: Start sector: 684071734 Apr 06 17:10:51 preclear_disk_WCJ2NAHF_10954: Pre-read: pre-read verification started (1/5).... Apr 06 17:10:52 preclear_disk_WCJ2NAHF_10954: Pre-Read: dd if=/dev/sda of=/dev/null bs=2097152 skip=0 count=5000981077504 conv=noerror iflag=nocache,count_bytes,skip_bytes Apr 06 18:15:27 preclear_disk_WCJ2NAHF_10954: Pre-Read: progress - 10% read @ 130 MB/s Apr 06 19:21:15 preclear_disk_WCJ2NAHF_10954: Pre-Read: progress - 20% read @ 129 MB/s Apr 06 20:29:42 preclear_disk_WCJ2NAHF_10954: Pre-Read: progress - 30% read @ 108 MB/s Apr 06 21:41:38 preclear_disk_WCJ2NAHF_10954: Pre-Read: progress - 40% read @ 115 MB/s Apr 06 22:57:57 preclear_disk_WCJ2NAHF_10954: Pre-Read: progress - 50% read @ 105 MB/s Apr 07 00:19:23 preclear_disk_WCJ2NAHF_10954: Pre-Read: progress - 60% read @ 90 MB/s Apr 07 01:47:16 preclear_disk_WCJ2NAHF_10954: Pre-Read: progress - 70% read @ 95 MB/s Apr 07 03:23:45 preclear_disk_WCJ2NAHF_10954: Pre-Read: progress - 80% read @ 81 MB/s Apr 07 05:13:06 preclear_disk_WCJ2NAHF_10954: Pre-Read: progress - 90% read @ 69 MB/s Apr 07 07:19:53 preclear_disk_WCJ2NAHF_10954: Pre-Read: dd - read 5000981077504 of 5000981077504 (0). Apr 07 07:19:53 preclear_disk_WCJ2NAHF_10954: Pre-Read: elapsed time - 14:08:59 Apr 07 07:19:53 preclear_disk_WCJ2NAHF_10954: Pre-Read: dd exit code - 0 Apr 07 07:19:54 preclear_disk_WCJ2NAHF_10954: Pre-read: pre-read verification completed! Apr 07 07:19:54 preclear_disk_WCJ2NAHF_10954: Zeroing: zeroing the disk started (1/5).... Apr 07 07:19:54 preclear_disk_WCJ2NAHF_10954: Zeroing: emptying the MBR. Apr 07 07:19:54 preclear_disk_WCJ2NAHF_10954: Zeroing: dd if=/dev/zero of=/dev/sda bs=2097152 seek=2097152 count=5000978980352 conv=notrunc iflag=count_bytes,nocache,fullblock oflag=seek_bytes Apr 07 07:19:54 preclear_disk_WCJ2NAHF_10954: Zeroing: dd pid [2492] Apr 07 08:19:40 preclear_disk_WCJ2NAHF_10954: Zeroing: progress - 10% zeroed @ 144 MB/s Apr 07 09:21:05 preclear_disk_WCJ2NAHF_10954: Zeroing: progress - 20% zeroed @ 138 MB/s Apr 07 10:24:35 preclear_disk_WCJ2NAHF_10954: Zeroing: progress - 30% zeroed @ 133 MB/s Apr 07 11:31:07 preclear_disk_WCJ2NAHF_10954: Zeroing: progress - 40% zeroed @ 119 MB/s Apr 07 12:40:58 preclear_disk_WCJ2NAHF_10954: Zeroing: progress - 50% zeroed @ 115 MB/s Apr 07 13:55:18 preclear_disk_WCJ2NAHF_10954: Zeroing: progress - 60% zeroed @ 114 MB/s Apr 07 15:15:26 preclear_disk_WCJ2NAHF_10954: Zeroing: progress - 70% zeroed @ 101 MB/s Apr 07 16:42:54 preclear_disk_WCJ2NAHF_10954: Zeroing: progress - 80% zeroed @ 93 MB/s Apr 07 18:21:10 preclear_disk_WCJ2NAHF_10954: Zeroing: progress - 90% zeroed @ 79 MB/s Apr 07 20:16:37 preclear_disk_WCJ2NAHF_10954: Zeroing: dd - wrote 5000981077504 of 5000981077504 (0). Apr 07 20:16:37 preclear_disk_WCJ2NAHF_10954: Zeroing: elapsed time - 12:56:40 Apr 07 20:16:37 preclear_disk_WCJ2NAHF_10954: Zeroing: dd exit code - 0 Apr 07 20:16:37 preclear_disk_WCJ2NAHF_10954: Zeroing: zeroing the disk completed! Apr 07 20:16:38 preclear_disk_WCJ2NAHF_10954: Signature: writing signature: 0 0 2 0 0 255 255 255 1 0 0 0 255 255 255 255 Apr 07 20:16:38 preclear_disk_WCJ2NAHF_10954: Signature: verifying unRAID's signature on the MBR ... Apr 07 20:16:38 preclear_disk_WCJ2NAHF_10954: Signature: Unraid preclear signature is valid! Apr 07 20:16:39 preclear_disk_WCJ2NAHF_10954: Post-Read: post-read verification started (1/5).... Apr 07 20:16:39 preclear_disk_WCJ2NAHF_10954: Post-Read: verifying the beginning of the disk. Apr 07 20:16:39 preclear_disk_WCJ2NAHF_10954: Post-Read: cmp /tmp/.preclear/sda/fifo /dev/zero Apr 07 20:16:39 preclear_disk_WCJ2NAHF_10954: Post-Read: dd if=/dev/sda of=/tmp/.preclear/sda/fifo count=2096640 skip=512 iflag=nocache,count_bytes,skip_bytes Apr 07 20:16:40 preclear_disk_WCJ2NAHF_10954: Post-Read: verifying the rest of the disk. Apr 07 20:16:40 preclear_disk_WCJ2NAHF_10954: Post-Read: cmp /tmp/.preclear/sda/fifo /dev/zero Apr 07 20:16:40 preclear_disk_WCJ2NAHF_10954: Post-Read: dd if=/dev/sda of=/tmp/.preclear/sda/fifo bs=2097152 skip=2097152 count=5000978980352 iflag=nocache,count_bytes,skip_bytes Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: cmp command failed - disk not zeroed Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd - read 14092861440 of 5000981077504 (4986888216064). Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: elapsed time - 0:01:51 Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd command failed, exit code [141]. Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 1027+0 records in Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 1026+0 records out Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 2151677952 bytes (2.2 GB, 2.0 GiB) copied, 16.452 s, 131 MB/s Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 1474+0 records in Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 1473+0 records out Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 3089104896 bytes (3.1 GB, 2.9 GiB) copied, 23.5275 s, 131 MB/s Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 1920+0 records in Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 1919+0 records out Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 4024434688 bytes (4.0 GB, 3.7 GiB) copied, 30.6582 s, 131 MB/s Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 2435+0 records in Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 2434+0 records out Apr 07 20:18:33 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 5104467968 bytes (5.1 GB, 4.8 GiB) copied, 38.9401 s, 131 MB/s Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 3030+0 records in Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 3029+0 records out Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 6352273408 bytes (6.4 GB, 5.9 GiB) copied, 48.3416 s, 131 MB/s Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 3700+0 records in Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 3699+0 records out Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 7757365248 bytes (7.8 GB, 7.2 GiB) copied, 58.9051 s, 132 MB/s Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 4437+0 records in Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 4436+0 records out Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 9302966272 bytes (9.3 GB, 8.7 GiB) copied, 70.546 s, 132 MB/s Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 5251+0 records in Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 5250+0 records out Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 11010048000 bytes (11 GB, 10 GiB) copied, 83.2843 s, 132 MB/s Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 6035+0 records in Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 6034+0 records out Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 12654215168 bytes (13 GB, 12 GiB) copied, 96.0797 s, 132 MB/s Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 6720+0 records in Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 6719+0 records out Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: dd output: 14090764288 bytes (14 GB, 13 GiB) copied, 107.935 s, 131 MB/s Apr 07 20:18:34 preclear_disk_WCJ2NAHF_10954: Post-Read: post-read verification failed! Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: Error: Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: ATTRIBUTE INITIAL NOW STATUS Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: Reallocated_Sector_Ct 0 0 - Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: Power_On_Hours 28 56 Up 28 Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: SATA_Downshift_Count 0 0 - Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: End-to-End_Error 0 0 - Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: Reported_Uncorrect 0 0 - Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: Airflow_Temperature_Cel 33 39 Up 6 Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: Current_Pending_Sector 0 0 - Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: Offline_Uncorrectable 0 0 - Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: UDMA_CRC_Error_Count 0 0 - Apr 07 20:18:35 preclear_disk_WCJ2NAHF_10954: S.M.A.R.T.: SMART overall-health self-assessment test result: PASSED Apr 07 20:18:36 preclear_disk_WCJ2NAHF_10954: error encountered, exiting... This time it failed at ~14GB post-read, as opposed to around 27 GB last time... suggesting to me it's likely not the drive, but rather something else (like a RAM issue you suggested). I'd expect it to fail around the same area if I had bad sectors...

Hey trurl - not yet, but I can't say I've had this issue before (or stability issues).... ram is Corsair LPX 3000 running its' specified XMP profile (ie. 3000mhz @ 15-17-17-35). It's also supported by the motherboard I'm running (ASRock Fatal1ty AB350 Gaming-ITX/ac with a R5 1600X @ stock settings). If it fails this time, I'll try dialling back the timings/clocks to 2400mhz.... CPU is running cool for an ITX system (55-60c / 130-140f), and the drive in the USB enclosure is sitting around the low 40-45c's (104-113f)... so nothing seems too abnormal in that regard. I wonder if it's something to do with virtualisation? I don't have any VM's currently running, but I wonder if it's related to VM configuration and USB/controller? (IOMMU groups & PCIe ACS Override...). If it fails this round, I'll try setting those back to stock...

Hey all, In almost an identical case to TexasDaddy above, I too had a seemingly unexplained post-read error around 30Gb in, when trying to preclear a Seagate Expansion 5Tb (2.5", ST5000LM000 drive) over USB. Unraid Version 6.9.1 Preclear 2021.03.18 Log: Apr 05 12:21:54 preclear_disk_WCJ2NAHF_15509: Command: /usr/local/emhttp/plugins/preclear.disk/script/preclear_disk.sh --notify 1 --frequency 2 --cycles 1 --no-prompt /dev/sdd Apr 05 12:21:54 preclear_disk_WCJ2NAHF_15509: Preclear Disk Version: 1.0.21 Apr 05 12:21:55 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T. info type: default Apr 05 12:21:55 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T. attrs type: default Apr 05 12:21:55 preclear_disk_WCJ2NAHF_15509: Disk size: 5000981077504 Apr 05 12:21:55 preclear_disk_WCJ2NAHF_15509: Disk blocks: 1220942645 Apr 05 12:21:55 preclear_disk_WCJ2NAHF_15509: Blocks (512 bytes): 9767541167 Apr 05 12:21:55 preclear_disk_WCJ2NAHF_15509: Block size: 4096 Apr 05 12:21:55 preclear_disk_WCJ2NAHF_15509: Start sector: 309 Apr 05 12:21:58 preclear_disk_WCJ2NAHF_15509: Pre-read: pre-read verification started (1/5).... Apr 05 12:21:58 preclear_disk_WCJ2NAHF_15509: Pre-Read: dd if=/dev/sdd of=/dev/null bs=2097152 skip=0 count=5000981077504 conv=noerror iflag=nocache,count_bytes,skip_bytes Apr 05 13:26:27 preclear_disk_WCJ2NAHF_15509: Pre-Read: progress - 10% read @ 135 MB/s Apr 05 14:32:23 preclear_disk_WCJ2NAHF_15509: Pre-Read: progress - 20% read @ 128 MB/s Apr 05 15:40:58 preclear_disk_WCJ2NAHF_15509: Pre-Read: progress - 30% read @ 111 MB/s Apr 05 16:52:53 preclear_disk_WCJ2NAHF_15509: Pre-Read: progress - 40% read @ 113 MB/s Apr 05 18:08:48 preclear_disk_WCJ2NAHF_15509: Pre-Read: progress - 50% read @ 104 MB/s Apr 05 19:30:03 preclear_disk_WCJ2NAHF_15509: Pre-Read: progress - 60% read @ 90 MB/s Apr 05 20:58:06 preclear_disk_WCJ2NAHF_15509: Pre-Read: progress - 70% read @ 94 MB/s Apr 05 22:35:02 preclear_disk_WCJ2NAHF_15509: Pre-Read: progress - 80% read @ 80 MB/s Apr 06 00:24:46 preclear_disk_WCJ2NAHF_15509: Pre-Read: progress - 90% read @ 67 MB/s Apr 06 02:31:39 preclear_disk_WCJ2NAHF_15509: Pre-Read: dd - read 5000981077504 of 5000981077504 (0). Apr 06 02:31:39 preclear_disk_WCJ2NAHF_15509: Pre-Read: elapsed time - 14:09:37 Apr 06 02:31:39 preclear_disk_WCJ2NAHF_15509: Pre-Read: dd exit code - 0 Apr 06 02:31:39 preclear_disk_WCJ2NAHF_15509: Pre-read: pre-read verification completed! Apr 06 02:31:39 preclear_disk_WCJ2NAHF_15509: Zeroing: zeroing the disk started (1/5).... Apr 06 02:31:39 preclear_disk_WCJ2NAHF_15509: Zeroing: emptying the MBR. Apr 06 02:31:39 preclear_disk_WCJ2NAHF_15509: Zeroing: dd if=/dev/zero of=/dev/sdd bs=2097152 seek=2097152 count=5000978980352 conv=notrunc iflag=count_bytes,nocache,fullblock oflag=seek_bytes Apr 06 02:31:39 preclear_disk_WCJ2NAHF_15509: Zeroing: dd pid [20883] Apr 06 03:32:52 preclear_disk_WCJ2NAHF_15509: Zeroing: progress - 10% zeroed @ 138 MB/s Apr 06 04:35:49 preclear_disk_WCJ2NAHF_15509: Zeroing: progress - 20% zeroed @ 136 MB/s Apr 06 05:40:27 preclear_disk_WCJ2NAHF_15509: Zeroing: progress - 30% zeroed @ 131 MB/s Apr 06 06:47:22 preclear_disk_WCJ2NAHF_15509: Zeroing: progress - 40% zeroed @ 113 MB/s Apr 06 07:57:50 preclear_disk_WCJ2NAHF_15509: Zeroing: progress - 50% zeroed @ 113 MB/s Apr 06 09:12:35 preclear_disk_WCJ2NAHF_15509: Zeroing: progress - 60% zeroed @ 114 MB/s Apr 06 10:32:40 preclear_disk_WCJ2NAHF_15509: Zeroing: progress - 70% zeroed @ 101 MB/s Apr 06 11:59:51 preclear_disk_WCJ2NAHF_15509: Zeroing: progress - 80% zeroed @ 93 MB/s Apr 06 13:38:36 preclear_disk_WCJ2NAHF_15509: Zeroing: progress - 90% zeroed @ 77 MB/s Apr 06 15:35:10 preclear_disk_WCJ2NAHF_15509: Zeroing: dd - wrote 5000981077504 of 5000981077504 (0). Apr 06 15:35:10 preclear_disk_WCJ2NAHF_15509: Zeroing: elapsed time - 13:03:28 Apr 06 15:35:10 preclear_disk_WCJ2NAHF_15509: Zeroing: dd exit code - 0 Apr 06 15:35:10 preclear_disk_WCJ2NAHF_15509: Zeroing: zeroing the disk completed! Apr 06 15:35:11 preclear_disk_WCJ2NAHF_15509: Signature: writing signature: 0 0 2 0 0 255 255 255 1 0 0 0 255 255 255 255 Apr 06 15:35:11 preclear_disk_WCJ2NAHF_15509: Signature: verifying unRAID's signature on the MBR ... Apr 06 15:35:11 preclear_disk_WCJ2NAHF_15509: Signature: Unraid preclear signature is valid! Apr 06 15:35:12 preclear_disk_WCJ2NAHF_15509: Post-Read: post-read verification started (1/5).... Apr 06 15:35:12 preclear_disk_WCJ2NAHF_15509: Post-Read: verifying the beginning of the disk. Apr 06 15:35:12 preclear_disk_WCJ2NAHF_15509: Post-Read: cmp /tmp/.preclear/sdd/fifo /dev/zero Apr 06 15:35:12 preclear_disk_WCJ2NAHF_15509: Post-Read: dd if=/dev/sdd of=/tmp/.preclear/sdd/fifo count=2096640 skip=512 iflag=nocache,count_bytes,skip_bytes Apr 06 15:35:13 preclear_disk_WCJ2NAHF_15509: Post-Read: verifying the rest of the disk. Apr 06 15:35:13 preclear_disk_WCJ2NAHF_15509: Post-Read: cmp /tmp/.preclear/sdd/fifo /dev/zero Apr 06 15:35:13 preclear_disk_WCJ2NAHF_15509: Post-Read: dd if=/dev/sdd of=/tmp/.preclear/sdd/fifo bs=2097152 skip=2097152 count=5000978980352 iflag=nocache,count_bytes,skip_bytes Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: cmp command failed - disk not zeroed Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd - read 26589790208 of 5000981077504 (4974391287296). Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: elapsed time - 0:03:27 Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd command failed, exit code [141]. Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 5770+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 5769+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 12098469888 bytes (12 GB, 11 GiB) copied, 91.5091 s, 132 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 6515+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 6514+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 13660848128 bytes (14 GB, 13 GiB) copied, 104.411 s, 131 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 7253+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 7252+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 15208546304 bytes (15 GB, 14 GiB) copied, 117.321 s, 130 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 7923+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 7922+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 16613638144 bytes (17 GB, 15 GiB) copied, 129.003 s, 129 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 8620+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 8619+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 18075353088 bytes (18 GB, 17 GiB) copied, 140.677 s, 128 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 9468+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 9467+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 19853737984 bytes (20 GB, 18 GiB) copied, 153.488 s, 129 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 10312+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 10311+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 21623734272 bytes (22 GB, 20 GiB) copied, 166.229 s, 130 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 11085+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 11084+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 23244832768 bytes (23 GB, 22 GiB) copied, 177.966 s, 131 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 11852+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 11851+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 24853348352 bytes (25 GB, 23 GiB) copied, 189.788 s, 131 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 12679+0 records in Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 12678+0 records out Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: dd output: 26587693056 bytes (27 GB, 25 GiB) copied, 202.644 s, 131 MB/s Apr 06 15:38:42 preclear_disk_WCJ2NAHF_15509: Post-Read: post-read verification failed! Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: Error: Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: ATTRIBUTE INITIAL NOW STATUS Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: Reallocated_Sector_Ct 0 0 - Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: Power_On_Hours 0 27 Up 27 Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: SATA_Downshift_Count 0 0 - Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: End-to-End_Error 0 0 - Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: Reported_Uncorrect 0 0 - Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: Airflow_Temperature_Cel 29 51 Up 22 Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: Current_Pending_Sector 0 0 - Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: Offline_Uncorrectable 0 0 - Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: UDMA_CRC_Error_Count 0 0 - Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: S.M.A.R.T.: SMART overall-health self-assessment test result: PASSED Apr 06 15:38:44 preclear_disk_WCJ2NAHF_15509: error encountered, exiting... There's a *small* chance that when I plugged another external SSD in to format last night that it caused some sort of weird bug (preclear was in progress). As an alternative test I've restarted Unraid; moved the USB to a rear I/O shield port (rather than a front connector); and re-started the test. One interesting thing I've noticed is that the drive is showing ZERO writes on the "Main" tab: Is this normal? I would have thought writing all the zero's would constitute writes? Unless it's something in relation to how Unassigned Devices operates (ie. technically I haven't written to the array... preclear_disk_WCJ2NAHF_15509.txt