Re: I/O error on data file, can't run backup

On Thursday 6. October 2011 07.07.11 Craig Ringer wrote:
> On 10/06/2011 03:06 AM, Leif Biberg Kristensen wrote:
> > I seemingly fixed the problem by stopping postgres and doing:
> >
> > balapapa 612249 # mv 11658 11658.old
> > balapapa 612249 # mv 11658.old 11658
> >
> > And the backup magically works.
>
> Woooooo! That's ... "interesting".
>
> I'd be inclined to suspect filesystem corruption, a file system bug /
> kernel bug (not very likely if you're on ext3), flakey RAM, etc rather
> than a failing disk ... though a failing disk _could_ still be the culprit.
>
> Use smartmontools to do a self-test; if 'smartctl -d ata -t long
> /dev/sdx' (where 'x' is the drive node) is reported by 'smartctl -d ata
> -a /dev/sdx' as having passed, there are no pending or uncorrectable
> sectors, and the disk status is reported as 'HEALTHY' your disk is quite
> likely OK. Note that a 'PASSED' or 'HEALTHY' report by its self doesn't
> mean much, disk firmwares often return HEALTHY even when the disk can't
> even read sector 0.
>
> I strongly recommend making a full backup, both a pg_dump *and* a
> file-system level copy of the datadir. Personally I'd then do a test
> restore of the pg_dump backup on a separate Pg instance and if it looked
> OK I'd re-initdb then reload from the dump.

Craig,
Thank you very much for the tip on smartmontools, which I didn't know about.
There indeed appears to be some problems with this disk:

8<---

balapapa ~ # smartctl -d ata -a /dev/sdb -s on
smartctl 5.40 2010-10-16 r3189 [x86_64-pc-linux-gnu] (local build)
Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net

=== START OF INFORMATION SECTION ===
Model Family:     Seagate Barracuda 7200.11 family
Device Model:     ST31000340AS
Serial Number:    9QJ1ZMHY
Firmware Version: SD15
User Capacity:    1 000 204 886 016 bytes
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   8
ATA Standard is:  ATA-8-ACS revision 4
Local Time is:    Thu Oct  6 07:46:19 2011 CEST

==> WARNING: There are known problems with these drives,
AND THIS FIRMWARE VERSION IS AFFECTED,
see the following Seagate web pages:
http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=207931
http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=207951

SMART support is: Available - device has SMART capability.
SMART support is: Disabled

=== START OF ENABLE/DISABLE COMMANDS SECTION ===
SMART 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:      (  25) The self-test routine was aborted by
                                        the host.
Total time to complete Offline
data collection:                 ( 650) 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:        ( 236) minutes.
Conveyance self-test routine
recommended polling time:        (   2) minutes.
SCT capabilities:              (0x103b) SCT Status supported.
                                        SCT Error Recovery Control supported.
                                        SCT Feature Control supported.
                                        SCT Data Table 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   114   099   006    Pre-fail  Always
-       61796058
  3 Spin_Up_Time            0x0003   094   092   000    Pre-fail  Always
-       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age   Always
-       46
  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always
-       1
  7 Seek_Error_Rate         0x000f   045   045   030    Pre-fail  Always
-       3848329867033
  9 Power_On_Hours          0x0032   076   076   000    Old_age   Always
-       21358
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always
-       0
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always
-       141
184 End-to-End_Error        0x0032   100   100   099    Old_age   Always
-       0
187 Reported_Uncorrect      0x0032   016   016   000    Old_age   Always
-       84
188 Command_Timeout         0x0032   100   100   000    Old_age   Always
-       0
189 High_Fly_Writes         0x003a   100   100   000    Old_age   Always
-       0
190 Airflow_Temperature_Cel 0x0022   063   049   045    Old_age   Always
-       37 (Min/Max 37/37)
194 Temperature_Celsius     0x0022   037   051   000    Old_age   Always
-       37 (0 23 0 0)
195 Hardware_ECC_Recovered  0x001a   018   014   000    Old_age   Always
-       61796058
197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always
-       2
198 Offline_Uncorrectable   0x0010   100   100   000    Old_age   Offline      -
2
199 UDMA_CRC_Error_Count    0x003e   200   200   000    Old_age   Always
-       0

SMART Error Log Version: 1
ATA Error Count: 84 (device log contains only the most recent five errors)
        CR = Command Register [HEX]
        FR = Features Register [HEX]
        SC = Sector Count Register [HEX]
        SN = Sector Number Register [HEX]
        CL = Cylinder Low Register [HEX]
        CH = Cylinder High Register [HEX]
        DH = Device/Head Register [HEX]
        DC = Device Command Register [HEX]
        ER = Error register [HEX]
        ST = Status register [HEX]
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 84 occurred at disk power-on lifetime: 19483 hours (811 days + 19 hours)
  When the command that caused the error occurred, the device was active or
idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  40 51 00 ff ff ff 0f  Error: UNC at LBA = 0x0fffffff = 268435455

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  25 00 08 ff ff ff ef 00      11:02:43.659  READ DMA EXT
  27 00 00 00 00 00 e0 00      11:02:43.658  READ NATIVE MAX ADDRESS EXT
  ec 00 00 00 00 00 a0 00      11:02:43.638  IDENTIFY DEVICE
  ef 03 46 00 00 00 a0 00      11:02:43.619  SET FEATURES [Set transfer mode]
  27 00 00 00 00 00 e0 00      11:02:43.558  READ NATIVE MAX ADDRESS EXT

Error 83 occurred at disk power-on lifetime: 19483 hours (811 days + 19 hours)
  When the command that caused the error occurred, the device was active or
idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  40 51 00 ff ff ff 0f  Error: UNC at LBA = 0x0fffffff = 268435455

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  25 00 08 ff ff ff ef 00      11:02:40.589  READ DMA EXT
  27 00 00 00 00 00 e0 00      11:02:40.588  READ NATIVE MAX ADDRESS EXT
  ec 00 00 00 00 00 a0 00      11:02:40.568  IDENTIFY DEVICE
  ef 03 46 00 00 00 a0 00      11:02:40.549  SET FEATURES [Set transfer mode]
  27 00 00 00 00 00 e0 00      11:02:40.498  READ NATIVE MAX ADDRESS EXT

Error 82 occurred at disk power-on lifetime: 19483 hours (811 days + 19 hours)
  When the command that caused the error occurred, the device was active or
idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  40 51 00 ff ff ff 0f  Error: UNC at LBA = 0x0fffffff = 268435455

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  25 00 08 ff ff ff ef 00      11:02:37.539  READ DMA EXT
  27 00 00 00 00 00 e0 00      11:02:37.538  READ NATIVE MAX ADDRESS EXT
  ec 00 00 00 00 00 a0 00      11:02:37.518  IDENTIFY DEVICE
  ef 03 46 00 00 00 a0 00      11:02:37.499  SET FEATURES [Set transfer mode]
  27 00 00 00 00 00 e0 00      11:02:37.448  READ NATIVE MAX ADDRESS EXT

Error 81 occurred at disk power-on lifetime: 19483 hours (811 days + 19 hours)
  When the command that caused the error occurred, the device was active or
idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  40 51 00 ff ff ff 0f  Error: UNC at LBA = 0x0fffffff = 268435455

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  25 00 08 ff ff ff ef 00      11:02:34.459  READ DMA EXT
  27 00 00 00 00 00 e0 00      11:02:34.458  READ NATIVE MAX ADDRESS EXT
  ec 00 00 00 00 00 a0 00      11:02:34.438  IDENTIFY DEVICE
  ef 03 46 00 00 00 a0 00      11:02:34.419  SET FEATURES [Set transfer mode]
  27 00 00 00 00 00 e0 00      11:02:34.348  READ NATIVE MAX ADDRESS EXT

Error 80 occurred at disk power-on lifetime: 19483 hours (811 days + 19 hours)
  When the command that caused the error occurred, the device was active or
idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  40 51 00 ff ff ff 0f  Error: UNC at LBA = 0x0fffffff = 268435455

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  25 00 08 ff ff ff ef 00      11:02:31.369  READ DMA EXT
  27 00 00 00 00 00 e0 00      11:02:31.368  READ NATIVE MAX ADDRESS EXT
  ec 00 00 00 00 00 a0 00      11:02:31.348  IDENTIFY DEVICE
  ef 03 46 00 00 00 a0 00      11:02:31.329  SET FEATURES [Set transfer mode]
  27 00 00 00 00 00 e0 00      11:02:31.278  READ NATIVE MAX ADDRESS EXT

SMART Self-test log structure revision number 1
No self-tests have been logged.  [To run self-tests, use: smartctl -t]


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.

8<---

I'm not a hard disk guru, and this info doesn't really say anything specific to
me. Wrt the firmware issue, I went to the Seagate site and downloaded and
burned an ISO, rebooted and followed the instructions, but the firmware update
failed with "unexpected disk type" or something to that effect, although I'm
positively certain that I downloaded the correct ISO and the program initially
identified the disk correctly. The download page is
<http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=207951>
and the ISO is the bottommost, for ST31000340AS. I'm going to send a mail to
the Seagate support about it, but first I have to rerun the procedure and get
the exact messages.

regards, Leif.