Disk failed a number of SMART tests, now seems to pass them...

[Kailee71]

Hi all,

just a question out of interest; I have a disk that was getting errors;

Code:

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       -       94
  3 Spin_Up_Time            0x0027   181   174   021    Pre-fail  Always       -       7908
  4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       813
  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   062   062   000    Old_age   Always       -       27861
 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   100   100   000    Old_age   Always       -       696
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       368
193 Load_Cycle_Count        0x0032   196   196   000    Old_age   Always       -       14031
194 Temperature_Celsius     0x0022   115   096   000    Old_age   Always       -       37
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      -       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  Extended offline    Completed without error       00%     27862         -
# 2  Short offline       Completed without error       00%     27656         -
# 3  Short offline       Completed: read failure       40%     27644         6060304
# 4  Short offline       Completed: read failure       40%     27630         6060304
# 5  Short offline       Completed: read failure       40%     27589         6060304
# 6  Short offline       Completed: read failure       40%     27575         6060304
# 7  Short offline       Completed: read failure       40%     27565         6060304
# 8  Short offline       Completed: read failure       10%     27563         6060304
# 9  Short offline       Completed: read failure       10%     27554         6060304
#10  Short offline       Completed: read failure       40%     27536         6060304
#11  Short offline       Completed: read failure       40%     27530         6060304
#12  Short offline       Completed: read failure       40%     27524         6060304
#13  Short offline       Completed: read failure       10%     27497         6060304
#14  Short offline       Completed: read failure       40%     27492         6060304
#15  Short offline       Completed: read failure       40%     27478         6060304
#16  Short offline       Completed: read failure       40%     27477         6060304
#17  Short offline       Completed without error       00%     27455         -
#18  Short offline       Completed: read failure       50%     27430         6060080
#19  Short offline       Completed without error       00%     27406         -
#20  Short offline       Completed without error       00%     27373         -
#21  Short offline       Completed without error       00%     27360         -
15 of 15 failed self-tests are outdated by newer successful extended offline self-test # 1

However recently it has started passing tests. I have (slightly) improved ventilation in the chassis but temps were only 38-40 celsius before, now down to 31-32...
I'll be replacing the disk anyway (it's got plenty of hours on it, and the first few months I hadn't disabled the load cycles), but out of interest, are there situations where a disk can "magically" heal itself?

TIA

Kai.

 

[Etorix]

As far as I know there is no magic… Have you replaced a cable while improving ventilation? A bad cable could explain errors from what appears to be an old but otherwise healthy disk.

 

[Kailee71]

No, no new cables. I improved the cooling by moving the disks around the chassis though; so the disk now has a different spot on the backplane (LFF DL380p). Before I had six disks all bunched up on one side and the other half of the chassis was empty (in terms of disks), now theý're evenly spaced out so there's a disk's worth space between them in the middle...
Here's a pic before (red x where a disk sits):

and now:

Maybe I'll leave it in for now and monitor how it goes...

 

[Etorix]

You may have a bad connector in the backplane then. Anyway, it now works.

 

[Johnnie Black]

SMART read failure is not a cable/connection problem, it's a disk surface problem, it's not that unusual for a disk to get "better", sometimes bad sectors can turn good after being written over, other times, marginal sectors that were failing to read can start to work, of course it's never a good sign, and difficult to predict if the disk will stay healthy for long, it can be good for monts, of fail again tomorrow.

 

[HarambeLives]

If it were me, I would replace it.

I had a drive do this in my Synology a while back, I checked it again and it read fine. I cleared the error in the array and went about my business.

Then, I went on vacation and 30 mins after I left, the drive alerted. And 3 days into vacation, a second one did. If I didn't have a RAID6 setup, I'd have been toast

 

[Kailee71]

yes that always happens I guess. I have no plans for extended holidays at the moment so I'm expecting it to live for a while longer ;-). But humour aside, I am keeping a close watch on the disk and replacing it at the next sign of *anything*.

Kai.