Pool degraded - puzzled by SMART results

Kevin Horton

Kevin Horton

Guru
Joined
Dec 2, 2015
Messages
730
The main pool on my main NAS became degraded overnight. The pool is 8 x 4TB WD Reds (the good old ones, before SMR came to the scene) in raidz2. I have multiple good backups of the data, on and off site. I have a similar spare disk on the shelf, burned in after I bought it last year (also a CMR disk).

The disk that was faulted has roughly 33725 hours of service, or approaching 4 years. This is the first time this disk has given trouble.

Code:
zpool status
  pool: main
 state: DEGRADED
status: One or more devices are faulted in response to persistent errors.
    Sufficient replicas exist for the pool to continue functioning in a
    degraded state.
action: Replace the faulted device, or use 'zpool clear' to mark the device
    repaired.
  scan: scrub repaired 548K in 10:48:21 with 0 errors on Tue Dec 22 07:48:54 2020
config:

    NAME                                            STATE     READ WRITE CKSUM
    main                                            DEGRADED     0     0     0
      raidz2-0                                      DEGRADED     0     0     0
        gptid/73e9c0c5-d607-11e6-8ce7-0cc47ad9b1ca  ONLINE       0     0     0
        gptid/749fe03a-d607-11e6-8ce7-0cc47ad9b1ca  ONLINE       0     0     0
        gptid/75508dd8-d607-11e6-8ce7-0cc47ad9b1ca  ONLINE       0     0     0
        gptid/76057e53-d607-11e6-8ce7-0cc47ad9b1ca  ONLINE       0     0     0
        gptid/76b682c2-d607-11e6-8ce7-0cc47ad9b1ca  FAULTED     52     0     0  too many errors
        gptid/7760db32-d607-11e6-8ce7-0cc47ad9b1ca  ONLINE       0     0     0
        gptid/781a0c8e-d607-11e6-8ce7-0cc47ad9b1ca  ONLINE       0     0     0
        gptid/78ce7800-d607-11e6-8ce7-0cc47ad9b1ca  ONLINE       0     0     0

errors: No known data errors


I ran a long SMART test, which passed. See the full smartctl output below.

Code:
smartctl -x /dev/da3
smartctl 7.1 2019-12-30 r5022 [FreeBSD 12.2-RELEASE-p2 amd64] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Western Digital Red
Device Model:     WDC WD40EFRX-68WT0N0
Serial Number:    WD-WCC4E2JXXXXXXX
LU WWN Device Id: 5 0014ee 20d470427
Firmware Version: 82.00A82
User Capacity:    4,000,787,030,016 bytes [4.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    5400 rpm
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-2 (minor revision not indicated)
SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Tue Dec 22 18:04:05 2020 PST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
AAM feature is:   Unavailable
APM feature is:   Unavailable
Rd look-ahead is: Enabled
Write cache is:   Enabled
DSN feature is:   Unavailable
ATA Security is:  Disabled, NOT FROZEN [SEC1]
Wt Cache Reorder: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status:  (0x00)    Offline data collection activity
                    was never started.
                    Auto Offline Data Collection: Disabled.
Self-test execution status:      (   0)    The previous self-test routine completed
                    without error or no self-test has ever
                    been run.
Total time to complete Offline
data collection:         (51720) seconds.
Offline data collection
capabilities:              (0x7b) SMART execute Offline immediate.
                    Auto Offline data collection on/off support.
                    Suspend Offline collection upon new
                    command.
                    Offline surface scan supported.
                    Self-test supported.
                    Conveyance Self-test supported.
                    Selective Self-test supported.
SMART capabilities:            (0x0003)    Saves SMART data before entering
                    power-saving mode.
                    Supports SMART auto save timer.
Error logging capability:        (0x01)    Error logging supported.
                    General Purpose Logging supported.
Short self-test routine
recommended polling time:      (   2) minutes.
Extended self-test routine
recommended polling time:      ( 517) minutes.
Conveyance self-test routine
recommended polling time:      (   5) minutes.
SCT capabilities:            (0x703d)    SCT Status supported.
                    SCT Error Recovery Control supported.
                    SCT Feature Control supported.
                    SCT Data Table supported.

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAGS    VALUE WORST THRESH FAIL RAW_VALUE
  1 Raw_Read_Error_Rate     POSR-K   200   200   051    -    0
  3 Spin_Up_Time            POS--K   196   175   021    -    7158
  4 Start_Stop_Count        -O--CK   100   100   000    -    134
  5 Reallocated_Sector_Ct   PO--CK   200   200   140    -    0
  7 Seek_Error_Rate         -OSR-K   200   200   000    -    0
  9 Power_On_Hours          -O--CK   054   054   000    -    33724
 10 Spin_Retry_Count        -O--CK   100   100   000    -    0
 11 Calibration_Retry_Count -O--CK   100   100   000    -    0
 12 Power_Cycle_Count       -O--CK   100   100   000    -    134
192 Power-Off_Retract_Count -O--CK   200   200   000    -    88
193 Load_Cycle_Count        -O--CK   200   200   000    -    1214
194 Temperature_Celsius     -O---K   115   112   000    -    37
196 Reallocated_Event_Count -O--CK   200   200   000    -    0
197 Current_Pending_Sector  -O--CK   200   200   000    -    0
198 Offline_Uncorrectable   ----CK   100   253   000    -    0
199 UDMA_CRC_Error_Count    -O--CK   200   200   000    -    0
200 Multi_Zone_Error_Rate   ---R--   200   200   000    -    0
                            ||||||_ K auto-keep
                            |||||__ C event count
                            ||||___ R error rate
                            |||____ S speed/performance
                            ||_____ O updated online
                            |______ P prefailure warning

General Purpose Log Directory Version 1
SMART           Log Directory Version 1 [multi-sector log support]
Address    Access  R/W   Size  Description
0x00       GPL,SL  R/O      1  Log Directory
0x01           SL  R/O      1  Summary SMART error log
0x02           SL  R/O      5  Comprehensive SMART error log
0x03       GPL     R/O      6  Ext. Comprehensive SMART error log
0x06           SL  R/O      1  SMART self-test log
0x07       GPL     R/O      1  Extended self-test log
0x09           SL  R/W      1  Selective self-test log
0x10       GPL     R/O      1  NCQ Command Error log
0x11       GPL     R/O      1  SATA Phy Event Counters log
0x21       GPL     R/O      1  Write stream error log
0x22       GPL     R/O      1  Read stream error log
0x80-0x9f  GPL,SL  R/W     16  Host vendor specific log
0xa0-0xa7  GPL,SL  VS      16  Device vendor specific log
0xa8-0xb6  GPL,SL  VS       1  Device vendor specific log
0xb7       GPL,SL  VS      39  Device vendor specific log
0xbd       GPL,SL  VS       1  Device vendor specific log
0xc0       GPL,SL  VS       1  Device vendor specific log
0xc1       GPL     VS      93  Device vendor specific log
0xe0       GPL,SL  R/W      1  SCT Command/Status
0xe1       GPL,SL  R/W      1  SCT Data Transfer

SMART Extended Comprehensive Error Log Version: 1 (6 sectors)
Device Error Count: 2
    CR     = Command Register
    FEATR  = Features Register
    COUNT  = Count (was: Sector Count) Register
    LBA_48 = Upper bytes of LBA High/Mid/Low Registers ]  ATA-8
    LH     = LBA High (was: Cylinder High) Register    ]   LBA
    LM     = LBA Mid (was: Cylinder Low) Register      ] Register
    LL     = LBA Low (was: Sector Number) Register     ]
    DV     = Device (was: Device/Head) Register
    DC     = Device Control Register
    ER     = Error register
    ST     = Status register
Powered_Up_Time is measured from power on, and printed as
DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,
SS=sec, and sss=millisec. It "wraps" after 49.710 days.

Error 2 [1] occurred at disk power-on lifetime: 33711 hours (1404 days + 15 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER -- ST COUNT  LBA_48  LH LM LL DV DC
  -- -- -- == -- == == == -- -- -- -- --
  40 -- 51 00 01 00 00 c0 75 4e 30 40 00  Error: UNC at LBA = 0xc0754e30 = 3228913200

  Commands leading to the command that caused the error were:
  CR FEATR COUNT  LBA_48  LH LM LL DV DC  Powered_Up_Time  Command/Feature_Name
  -- == -- == -- == == == -- -- -- -- --  ---------------  --------------------
  60 00 10 00 38 00 00 c0 75 53 10 40 00 45d+09:49:32.377  READ FPDMA QUEUED
  60 00 18 00 30 00 00 c0 75 52 f8 40 00 45d+09:49:32.377  READ FPDMA QUEUED
  60 00 10 00 28 00 00 c0 75 52 e8 40 00 45d+09:49:32.377  READ FPDMA QUEUED
  60 00 10 00 20 00 00 c0 75 52 d8 40 00 45d+09:49:32.377  READ FPDMA QUEUED
  60 00 18 00 18 00 00 c0 75 52 c0 40 00 45d+09:49:32.377  READ FPDMA QUEUED

Error 1 [0] occurred at disk power-on lifetime: 33689 hours (1403 days + 17 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER -- ST COUNT  LBA_48  LH LM LL DV DC
  -- -- -- == -- == == == -- -- -- -- --
  04 -- 51 00 00 00 00 c0 75 4e 30 00 00

  Commands leading to the command that caused the error were:
  CR FEATR COUNT  LBA_48  LH LM LL DV DC  Powered_Up_Time  Command/Feature_Name
  -- == -- == -- == == == -- -- -- -- --  ---------------  --------------------
  ea 00 00 00 00 00 00 00 00 00 00 40 00 44d+12:18:21.730  FLUSH CACHE EXT
  61 00 30 00 00 00 00 c0 75 53 58 40 00 44d+12:18:21.729  WRITE FPDMA QUEUED
  61 00 08 00 00 00 00 58 16 bc d8 40 00 44d+12:18:21.729  WRITE FPDMA QUEUED
  61 00 08 00 00 00 00 58 09 55 00 40 00 44d+12:18:21.729  WRITE FPDMA QUEUED
  61 00 30 00 00 00 00 55 1e 1d 40 40 00 44d+12:18:21.728  WRITE FPDMA QUEUED

SMART Extended Self-test Log Version: 1 (1 sectors)
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Extended offline    Completed without error       00%     33723         -
# 2  Short offline       Completed without error       00%     33702         -
# 3  Short offline       Completed without error       00%     33678         -
# 4  Extended offline    Completed without error       00%     33667         -
# 5  Short offline       Completed without error       00%     33654         -
# 6  Short offline       Completed without error       00%     33630         -
# 7  Short offline       Completed without error       00%     33606         -
# 8  Short offline       Completed without error       00%     33582         -
# 9  Short offline       Completed without error       00%     33558         -
#10  Short offline       Completed without error       00%     33534         -
#11  Short offline       Completed without error       00%     33510         -
#12  Extended offline    Completed without error       00%     33498         -
#13  Short offline       Completed without error       00%     33486         -
#14  Short offline       Completed without error       00%     33465         -
#15  Short offline       Completed without error       00%     33438         -
#16  Short offline       Completed without error       00%     33417         -
#17  Short offline       Completed without error       00%     33390         -
#18  Short offline       Completed without error       00%     33366         -

SMART Selective self-test log data structure revision number 1
 SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS
    1        0        0  Not_testing
    2        0        0  Not_testing
    3        0        0  Not_testing
    4        0        0  Not_testing
    5        0        0  Not_testing
Selective self-test flags (0x0):
  After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.

SCT Status Version:                  3
SCT Version (vendor specific):       258 (0x0102)
Device State:                        Active (0)
Current Temperature:                    37 Celsius
Power Cycle Min/Max Temperature:     36/39 Celsius
Lifetime    Min/Max Temperature:      3/40 Celsius
Under/Over Temperature Limit Count:   0/0
Vendor specific:
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

SCT Temperature History Version:     2
Temperature Sampling Period:         1 minute
Temperature Logging Interval:        1 minute
Min/Max recommended Temperature:      0/60 Celsius
Min/Max Temperature Limit:           -41/85 Celsius
Temperature History Size (Index):    478 (52)

Index    Estimated Time   Temperature Celsius
  53    2020-12-22 10:07    38  *******************
 ...    ..( 34 skipped).    ..  *******************
  88    2020-12-22 10:42    38  *******************
  89    2020-12-22 10:43    39  ********************
  90    2020-12-22 10:44    39  ********************
  91    2020-12-22 10:45    39  ********************
  92    2020-12-22 10:46    38  *******************
 ...    ..( 11 skipped).    ..  *******************
 104    2020-12-22 10:58    38  *******************
 105    2020-12-22 10:59    37  ******************
 ...    ..( 12 skipped).    ..  ******************
 118    2020-12-22 11:12    37  ******************
 119    2020-12-22 11:13    38  *******************
 ...    ..(410 skipped).    ..  *******************
  52    2020-12-22 18:04    38  *******************

SCT Error Recovery Control:
           Read:     70 (7.0 seconds)
          Write:     70 (7.0 seconds)

Device Statistics (GP/SMART Log 0x04) not supported

Pending Defects log (GP Log 0x0c) not supported

SATA Phy Event Counters (GP Log 0x11)
ID      Size     Value  Description
0x0001  2            0  Command failed due to ICRC error
0x0002  2            0  R_ERR response for data FIS
0x0003  2            0  R_ERR response for device-to-host data FIS
0x0004  2            0  R_ERR response for host-to-device data FIS
0x0005  2            0  R_ERR response for non-data FIS
0x0006  2            0  R_ERR response for device-to-host non-data FIS
0x0007  2            0  R_ERR response for host-to-device non-data FIS
0x0008  2            0  Device-to-host non-data FIS retries
0x0009  2            1  Transition from drive PhyRdy to drive PhyNRdy
0x000a  2            1  Device-to-host register FISes sent due to a COMRESET
0x000b  2            0  CRC errors within host-to-device FIS
0x000f  2            0  R_ERR response for host-to-device data FIS, CRC
0x0012  2            0  R_ERR response for host-to-device non-data FIS, CRC
0x8000  4        35106  Vendor specific


I don't know how to interpret the following portion of the SMART output:

Code:
SMART Extended Comprehensive Error Log Version: 1 (6 sectors)
Device Error Count: 2
    CR     = Command Register
    FEATR  = Features Register
    COUNT  = Count (was: Sector Count) Register
    LBA_48 = Upper bytes of LBA High/Mid/Low Registers ]  ATA-8
    LH     = LBA High (was: Cylinder High) Register    ]   LBA
    LM     = LBA Mid (was: Cylinder Low) Register      ] Register
    LL     = LBA Low (was: Sector Number) Register     ]
    DV     = Device (was: Device/Head) Register
    DC     = Device Control Register
    ER     = Error register
    ST     = Status register
Powered_Up_Time is measured from power on, and printed as
DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,
SS=sec, and sss=millisec. It "wraps" after 49.710 days.

Error 2 [1] occurred at disk power-on lifetime: 33711 hours (1404 days + 15 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER -- ST COUNT  LBA_48  LH LM LL DV DC
  -- -- -- == -- == == == -- -- -- -- --
  40 -- 51 00 01 00 00 c0 75 4e 30 40 00  Error: UNC at LBA = 0xc0754e30 = 3228913200

  Commands leading to the command that caused the error were:
  CR FEATR COUNT  LBA_48  LH LM LL DV DC  Powered_Up_Time  Command/Feature_Name
  -- == -- == -- == == == -- -- -- -- --  ---------------  --------------------
  60 00 10 00 38 00 00 c0 75 53 10 40 00 45d+09:49:32.377  READ FPDMA QUEUED
  60 00 18 00 30 00 00 c0 75 52 f8 40 00 45d+09:49:32.377  READ FPDMA QUEUED
  60 00 10 00 28 00 00 c0 75 52 e8 40 00 45d+09:49:32.377  READ FPDMA QUEUED
  60 00 10 00 20 00 00 c0 75 52 d8 40 00 45d+09:49:32.377  READ FPDMA QUEUED
  60 00 18 00 18 00 00 c0 75 52 c0 40 00 45d+09:49:32.377  READ FPDMA QUEUED

Error 1 [0] occurred at disk power-on lifetime: 33689 hours (1403 days + 17 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER -- ST COUNT  LBA_48  LH LM LL DV DC
  -- -- -- == -- == == == -- -- -- -- --
  04 -- 51 00 00 00 00 c0 75 4e 30 00 00

  Commands leading to the command that caused the error were:
  CR FEATR COUNT  LBA_48  LH LM LL DV DC  Powered_Up_Time  Command/Feature_Name
  -- == -- == -- == == == -- -- -- -- --  ---------------  --------------------
  ea 00 00 00 00 00 00 00 00 00 00 40 00 44d+12:18:21.730  FLUSH CACHE EXT
  61 00 30 00 00 00 00 c0 75 53 58 40 00 44d+12:18:21.729  WRITE FPDMA QUEUED
  61 00 08 00 00 00 00 58 16 bc d8 40 00 44d+12:18:21.729  WRITE FPDMA QUEUED
  61 00 08 00 00 00 00 58 09 55 00 40 00 44d+12:18:21.729  WRITE FPDMA QUEUED
  61 00 30 00 00 00 00 55 1e 1d 40 40 00 44d+12:18:21.728  WRITE FPDMA QUEUED


It looks like both errors occurred very recently, and both are at the same LBA, judging by the LH, LM and LL values. What is a UNC error? Uncorrectable read error? I would have expected it to fail the long SMART test, or show something interesting in the SMART data.

I ran a zpool clear and the pool resilvered with zero errors. I'll keep the disk in service for now, but replace it if it degrades the pool again.

Thanks in advance for any advice or comments.
 
Jailer

Jailer

Not strong, but bad
Joined
Sep 12, 2014
Messages
4,977
Found a link that describes a UNC error.

https://techoverflow.net/2016/07/25/how-to-interpret-smartctl-messages-like-error-unc-at-lba/

May have been a fluke, may be just fine. I've got a disk here that has several of those errors that occured at a previous point a long time ago and it's still running just fine. Mind you I would never put it in anything I trust with data that I care about but it still functions.

Considering the fact that the drive is over 4 years old if it were me I'd replace the drive. You had an uncorrectable error on your drive that was identified internally by SMART. But that's just my opinion and I tend to err on the side of caution.
 
Chris Moore

Chris Moore

Hall of Famer
Joined
May 2, 2015
Messages
10,079
From my point of view, if a drive is operating in such a way that a fault is caused, it is time to replace the drive.
I am in a bit of a drive hoarder though, I have enough spare drives to replace all the drives in my pool.
 
Kevin Horton

Kevin Horton

Guru
Joined
Dec 2, 2015
Messages
730
Jailer said:
Found a link that describes a UNC error.

https://techoverflow.net/2016/07/25/how-to-interpret-smartctl-messages-like-error-unc-at-lba/

May have been a fluke, may be just fine. I've got a disk here that has several of those errors that occured at a previous point a long time ago and it's still running just fine. Mind you I would never put it in anything I trust with data that I care about but it still functions.

Considering the fact that the drive is over 4 years old if it were me I'd replace the drive. You had an uncorrectable error on your drive that was identified internally by SMART. But that's just my opinion and I tend to err on the side of caution.
Click to expand...
Thanks for the link and advice. That was very useful.

And thanks @Chris Moore for your advice as well.
 
Chris Moore

Chris Moore

Hall of Famer
Joined
May 2, 2015
Messages
10,079
Kevin Horton

Kevin Horton

Guru
Joined
Dec 2, 2015
Messages
730
You must log in or register to reply here.

Important Announcement for the TrueNAS Community.

The TrueNAS Community has now been moved. This forum will now become READ-ONLY for historical purposes. Please feel free to join us on the new TrueNAS Community Forums.

Related topics on forums.truenas.com for thread: "Pool degraded - puzzled by SMART results"

Similar threads

G
Have 2 disk with errors in Raidz2. which one should be chang first?
Replies
11
Views
3K
GolDenis
G
N
Is This Drive Dying? Should it be replaced?
Replies
10
Views
2K
HoneyBadger
HoneyBadger
Murac
  • Locked
Help to confirm my drive's gone bad, please
Replies
10
Views
3K
Murac
Murac
Baenwort
  • Locked
  • Poll
is my drive failing?
Replies
5
Views
2K
Baenwort
Baenwort
L
  • Locked
Reading SMART info, defective disk?
Replies
4
Views
4K
lowlytech
L
Top