Watching a drive go bad

The other weekend I got around to rearranging some drives in my desktop work station.  This had an SSD for boot and applications and a RAID-1 (AMD motherboard RAID) for bulk storage.  The RAID-1 was built using two WD 2TB green drives and had been in use for about 2 years.

Once I had copied the data off the RAID-1 onto a new WD 2TB red drive I did a SMART test of the two old green drives.  One was flawless but the other had an issue:

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       -       0
  3 Spin_Up_Time            0x0027   170   167   021    Pre-fail  Always       -       6500
  4 Start_Stop_Count        0x0032   099   099   000    Old_age   Always       -       1190
  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   084   084   000    Old_age   Always       -       11739
10 Spin_Retry_Count        0x0032   100   100   000    Old_age   Always       -       0
11 Calibration_Retry_Count 0x0032   100   100   000    Old_age   Always       -       0
12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       1163
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       39
193 Load_Cycle_Count        0x0032   085   085   000    Old_age   Always       -       346739
194 Temperature_Celsius     0x0022   119   097   000    Old_age   Always       -       31
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   200   200   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      -       32

Note the Multi_Zone_Error_Rate (MZER) was at 32.  Typically I've never seen the MZER go much beyond about 5, so this was enough to make me think of preclearing to test them further.

I put both drives into empty slots in my unRAID tower and started a 2 pass preclear.  The good drive finished in the expected time, but the drive with the MZER issue took about 15 hours longer (most of that extra time was in the second pass).  When I looked at the SMART reports I saw nothing odd on the good drive but the bad drive was now showing:

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   175   175   051    Pre-fail  Always       -       16173
  3 Spin_Up_Time            0x0027   170   167   021    Pre-fail  Always       -       6500
  4 Start_Stop_Count        0x0032   099   099   000    Old_age   Always       -       1190
  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   084   084   000    Old_age   Always       -       11826
10 Spin_Retry_Count        0x0032   100   100   000    Old_age   Always       -       0
11 Calibration_Retry_Count 0x0032   100   100   000    Old_age   Always       -       0
12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       1163
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       39
193 Load_Cycle_Count        0x0032   085   085   000    Old_age   Always       -       346745
194 Temperature_Celsius     0x0022   117   097   000    Old_age   Always       -       33
196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   196   196   000    Old_age   Always       -       1364
198 Offline_Uncorrectable   0x0030   198   198   000    Old_age   Offline      -       799
199 UDMA_CRC_Error_Count    0x0032   200   200   000    Old_age   Always       -       0
200 Multi_Zone_Error_Rate   0x0008   185   185   000    Old_age   Offline      -       4029

Yikes!  looks like it was getting worse fast.

The preclear report for this drive shows that in the first pass 100 sectors went bad and in the second pass 1302 went bad - which would go to explaining why the second pass ran so much slower:

0 sectors were pending re-allocation before the start of the preclear.
0 sectors were pending re-allocation after pre-read in cycle 1 of 2.
0 sectors were pending re-allocation after zero of disk in cycle 1 of 2.
100 sectors were pending re-allocation after post-read in cycle 1 of 2.
0 sectors were pending re-allocation after zero of disk in cycle 2 of 2.
1302 sectors are pending re-allocation at the end of the preclear,
    a change of 1302 in the number of sectors pending re-allocation.
0 sectors had been re-allocated before the start of the preclear.
0 sectors are re-allocated at the end of the preclear,
    the number of sectors re-allocated did not change. 

Naturally I've started an RMA on this drive.

One of the reasons I was rearranging the drives in the first place was that no SMART tools would work with the motherboard RAID-1 drivers I have, so I was switching back to single drive AHCI mode so that I could check the SMART status from time to time.

Regards,

Stephen