Read errors but SMART is fine?


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Hi, I am new to unraid and wasn't experienced with disks.

 

Recently I wanted to add a parity disk to my data-disks-only-array. While building the parity, unraid reported a massive amount of read errors (More than 600,000) on Disk 2 (Error column in the main GUI).

 

Because I have read that this is often caused by cabling, I changed and switched the SATA cables multiple times. But the read errors didn't go away. So the drive is probably faulty. Meanwhile I already found several "dead" files. At the moment I am rescuing the readable data with unBALANCE to another disk.

 

But this is strange: While other people with read errors usually have pending sectors or something like that in their SMART reports, mine seems to be ok. The disk has a bad "UDMA CRC error count" but if I googled right, this is not really problematic.

 

Can I fix the disk somehow or do I have to bin it? I have attached the diagnostics (Downloaded after the read errors happened)

 

All disks are from ebay ("Refurbished") and have never been precleared. I will do this as soon as possible, maybe they are faulty too... And I have ordered brand new ones.

nas-diagnostics-20200601-1043.zip

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On 6/3/2020 at 6:00 PM, johnnie.black said:

Errors are logged as actual disk errors, though this is not 100% reliable, you can run an extended SMART test to confirm.

 

Thanks for your answer. Strangely, the extended SMART test finished without errors. But a preclear I ran afterwards, died because of syntax errors after some reading errors:

 

Jun 05 00:14:48 preclear_disk_WD-WCC130368601_1194: Pre-Read: progress - 90% read @ 88 MB/s
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: dd: error reading '/dev/sdb': Input/output error
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records in
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records out
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 3608331948032 bytes (3.6 TB, 3.3 TiB) copied, 29171.4 s, 124 MB/s
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: dd: error reading '/dev/sdb': Input/output error
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records in
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records out
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 3608331948032 bytes (3.6 TB, 3.3 TiB) copied, 29171.4 s, 124 MB/s
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: dd: error reading '/dev/sdb': Input/output error
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records in
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records out
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 3608331948032 bytes (3.6 TB, 3.3 TiB) copied, 29171.5 s, 124 MB/s
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: dd: error reading '/dev/sdb': Input/output error
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records in
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records out
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 3608331948032 bytes (3.6 TB, 3.3 TiB) copied, 29171.5 s, 124 MB/s
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: dd: error reading '/dev/sdb': Input/output error
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records in
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 1718084+11636 records out
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd output: 3608331948032 bytes (3.6 TB, 3.3 TiB) copied, 29171.5 s, 124 MB/s
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: dd process hung at 3608334045184, killing....
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Continuing disk read from byte 3608331948032
Jun 05 00:19:14 preclear_disk_WD-WCC130368601_1194: Pre-Read: dd if=/dev/sdb of=/dev/null bs=2097152 skip=3608331948032 count=392455081984 conv=notrunc,noerror iflag=nocache,count_bytes,skip_bytes
Jun 05 00:19:17 preclear_disk_WD-WCC130368601_1194: /usr/local/emhttp/plugins/preclear.disk/script/preclear_disk.sh: line 844: 8:06:10 + 3 : syntax error in expression (error token is ":06:10 + 3 ")
Jun 05 00:19:18 preclear_disk_WD-WCC130368601_1194: /usr/local/emhttp/plugins/preclear.disk/script/preclear_disk.sh: line 1139: 8:06:10 : syntax error in expression (error token is ":06:10 ")
Jun 05 00:19:18 preclear_disk_WD-WCC130368601_1194: Preclear: total elapsed time: 8:06:17

 

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19 hours ago, johnnie.black said:

Really looks like a disk problem, can you run another extended test?

 

Done. Completed again without errors. I also did another preclear (This time with the Joe L script), and at 90% pre-read it just stopped (No more progress was visible for multiple hours). The other preclear with the gfjardim script also died at about 90%.

 

I suspect the SMART system of this drive isn't working like it should.

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This time not. But the following reasons were enough for me to take the disk out of service:

  • Read errors while parity checking even after sata cable replacing and switching
  • Read errors while file moving, always with the same files, I couldn't move them (Tried it multiple times)
  • Two preclears with different scripts failed while pre-reading at about 90%
  • After removing the disk, my samba share performance increased A LOT (This problem got fixed). But at about the same time I upgraded Unraid from 6.7 to 6.8.3, so maybe it was not the disks fault. But I think so.
Edited by FloPinguin
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