Ran smartctl on my drive, not sure if this is good or bad

Question

I've been having problems with a drive in my Synology diskstation. I saw the following errors pop up on my /var/log/messages:

 ata6.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
 ata6.00: failed command: SMART
 ata6.00: cmd b0/d0:01:00:4f:c2/00:00:00:00:00/00 tag 0 pio 512 in
          res 40/00:01:06:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)
 ata6.00: status: { DRDY }

I don't know what this means, but it seems like there's a problem, and my disk array is unusable due to 100% IO Wait, so I figured this might be the culprit.

I then went and ran smartctl -a on this, and got the following output:

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:  (0x82) Offline data collection activity
                                        was completed without error.
                                        Auto Offline Data Collection: Enabled.
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:                (  584) 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:        (   1) minutes.
Extended self-test routine
recommended polling time:        ( 335) minutes.
Conveyance self-test routine
recommended polling time:        (   2) minutes.
SCT capabilities:              (0x3085) SCT Status supported.

SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000f   111   099   006    Pre-fail  Always       -       30661384
  3 Spin_Up_Time            0x0003   094   094   000    Pre-fail  Always       -       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age   Always       -       52
  5 Reallocated_Sector_Ct   0x0033   085   085   010    Pre-fail  Always       -       19440
  7 Seek_Error_Rate         0x000f   061   060   030    Pre-fail  Always       -       47258538769
  9 Power_On_Hours          0x0032   089   089   000    Old_age   Always       -       10454
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always       -       51
183 Runtime_Bad_Block       0x0032   092   092   000    Old_age   Always       -       8
184 End-to-End_Error        0x0032   100   100   099    Old_age   Always       -       0
187 Reported_Uncorrect      0x0032   100   100   000    Old_age   Always       -       0
188 Command_Timeout         0x0032   001   001   000    Old_age   Always       -       5384 5388 5388
189 High_Fly_Writes         0x003a   080   080   000    Old_age   Always       -       20
190 Airflow_Temperature_Cel 0x0022   072   046   045    Old_age   Always       -       28 (Min/Max 28/31)
191 G-Sense_Error_Rate      0x0032   100   100   000    Old_age   Always       -       0
192 Power-Off_Retract_Count 0x0032   100   100   000    Old_age   Always       -       49
193 Load_Cycle_Count        0x0032   094   094   000    Old_age   Always       -       12043
194 Temperature_Celsius     0x0022   028   054   000    Old_age   Always       -       28 (0 16 0 0 0)
197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0010   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x003e   200   200   000    Old_age   Always       -       0
240 Head_Flying_Hours       0x0000   100   253   000    Old_age   Offline      -       2440h+22m+08.819s
241 Total_LBAs_Written      0x0000   100   253   000    Old_age   Offline      -       17844897050
242 Total_LBAs_Read         0x0000   100   253   000    Old_age   Offline      -       27458866514

I don't understand what this output is saying. Can someone give me a hand and decipher this for me? I see that it said that the tests passed, but I also see something about "pre-fail", "old age" and the values in the table appear to be larger than the threshold.

Is this drive dying?

Answer 1

With 19,440 reallocated sectors, your drive is already on its last legs.

 5 Reallocated_Sector_Ct   0x0033   085   085   010    Pre-fail  Always       -       19440

This is generally the first attribute I look at on a spinning rust disk. Anything other than a zero raw value is a potential problem, as it means parts of the disk surface have been marked as bad internally, and reserved space is now filling in for the bad sectors. With large numbers of reallocated sectors you'll see performance problems, and eventually, lost data.

It will have to have a lot more bad sectors before SMART actually shows it as failing, but you can be sure that it is failing now, and should be replaced.

Answer 2

It turns out that it was the drive. As soon as I removed the drive from the array, even though it was in degraded mode, the array was instantly usable.