Current Pending sectors disappeared?

[danb35]

A couple of weeks ago, I started getting warning emails from my FreeNAS server that a disk was starting to show current/pending sectors. Looking at the SMART data, item 197 was at 5. Figuring this was a sign of the disk failing, I obtained a replacement disk, tested it, and installed it in my server. The array is resilvered and working without issue.

With that taken care of, I installed the old, believed-failing disk in another server and ran a full badblocks scan on it, which took a few days. After that, I pulled the SMART data again (below). To my surprise, item 197 is now 0. I'd figured, if anything, that the value would increase, with badblocks forcing repeated r/w to each sector on the disk. Can I trust this disk? I doubt I could RMA it with no errors showing.

Code:

[root@e-smith ~]# smartctl -a /dev/sdc
smartctl 5.43 2012-06-30 r3573 [x86_64-linux-2.6.32-431.29.2.el6.x86_64] (local build)
Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net

=== START OF INFORMATION SECTION ===
Device Model:     WDC WD30EFRX-68EUZN0
Serial Number:    WD-WCC4N1112375
LU WWN Device Id: 5 0014ee 20a20083a
Firmware Version: 80.00A80
User Capacity:    3,000,592,982,016 bytes [3.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   8
ATA Standard is:  ACS-2 (revision not indicated)
Local Time is:    Thu Sep 25 10:40:21 2014 EDT
SMART support is: Available - device has SMART capability.
SMART support is: 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: (39240) 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:  ( 394) 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          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x002f   200   200   051    Pre-fail  Always       -       87
  3 Spin_Up_Time            0x0027   180   180   021    Pre-fail  Always       -       5966
  4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       7
  5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x002e   200   200   000    Old_age   Always       -       0
  9 Power_On_Hours          0x0032   097   097   000    Old_age   Always       -       2783
 10 Spin_Retry_Count        0x0032   100   253   000    Old_age   Always       -       0
 11 Calibration_Retry_Count 0x0032   100   253   000    Old_age   Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       7
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       5
193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       10
194 Temperature_Celsius     0x0022   118   110   000    Old_age   Always       -       32
196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0030   100   253   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x0032   200   200   000    Old_age   Always       -       0
200 Multi_Zone_Error_Rate   0x0008   200   200   000    Old_age   Offline      -       0

SMART Error Log Version: 1
No Errors Logged

SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Short offline       Completed without error       00%      2677         -
# 2  Extended offline    Completed without error       00%      2663         -
# 3  Short offline       Completed without error       00%      2653         -
# 4  Short offline       Completed without error       00%      2629         -
# 5  Short offline       Completed without error       00%      2605         -
# 6  Short offline       Completed without error       00%      2581         -
# 7  Short offline       Completed without error       00%      2557         -
# 8  Short offline       Completed without error       00%      2533         -
# 9  Short offline       Completed without error       00%      2509         -
#10  Extended offline    Completed without error       00%      2495         -
#11  Short offline       Completed without error       00%      2485         -
#12  Short offline       Completed without error       00%      2461         -
#13  Short offline       Completed without error       00%      2437         -
#14  Short offline       Completed without error       00%      2413         -
#15  Short offline       Completed without error       00%      2389         -
#16  Short offline       Completed without error       00%      2367         -
#17  Short offline       Completed without error       00%      2341         -
#18  Extended offline    Completed without error       00%      2327         -
#19  Short offline       Completed without error       00%      2317         -
#20  Short offline       Completed without error       00%      2293         -
#21  Short offline       Completed without error       00%      2269         -

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.

 

[rs225]

I would say it is just as safe as any other drive. A few sector relocations is not a problem, but now that you've run badblocks (written and read every sector), any future growth could be a sign that there is a problem which is growing, and then you might not want to 'trust' that disk.

In other words, trust, but always have a backup.

 

[SirMaster]

Nobody can really tell you whether or not you should trust the disk. I guess you should probably trust it less.

Current Pending Sector Count
Count of "unstable" sectors (waiting to be remapped, because of unrecoverable read errors). If an unstable sector is subsequently read successfully, the sector is remapped and this value is decreased. Read errors on a sector will not remap the sector immediately (since the correct value cannot be read and so the value to remap is not known, and also it might become readable later); instead, the drive firmware remembers that the sector needs to be remapped, and will remap it the next time it's written.
However some drives will not immediately remap such sectors when written; instead the drive will first attempt to write to the problem sector and if the write operation is successful then the sector will be marked good (in this case, the "Reallocation Event Count" (0xC4) will not be increased). This is a serious shortcoming, for if such a drive contains marginal sectors that consistently fail only after some time has passed following a successful write operation, then the drive will never remap these problem sectors.