Zpool scrubs causes my pools to become degraded

[Caesar]

My Setup
=======
Build 8.3.0-Release-p1 x64 (r12825)
CPU AMD A4-3400
MB MSI A55M-P33
Memory 7655MB
Pool Name Zgroup1
Pool configuration 2 x Raidz Vdev
Vdev configuration RaidZ (3 x 500GB) + RaidZ (3 x 2TB)

History
=====
I have only had this setup for about 3 months now Everything was bought new except the original hard drives. The first scrub showed that a disk was going bad (lots of write/cksum errors) so I replaced all of them in that Vdev. I went from 500GB to 2TB WD Red drives. The next scrub showed a status very similar to what is showing now and the errors and the drive with the error was on the same sata port (ada5) that the first scrub's bad drive was on. When I do a zpool status I do not see read write or cksum errors. All I see is the status One or more devices has experienced an unrecoverable error.... When I try a zpool clear is when the pool will become degraded and the drive on ada5 will be offline. I shut the server down, replaced the SATA cable and issue another zpool clear and then the drive comes back online and my pool is healthy again. That was two weeks ago 5/15. I changed my scub to biweekly to troubleshoot this issue.

Here is the output for a zpool status -v

Code:

zpool status -v
  pool: Zgroup1
 state: ONLINE
status: One or more devices has experienced an unrecoverable error.  An
        attempt was made to correct the error.  Applications are unaffected.
action: Determine if the device needs to be replaced, and clear the errors
        using 'zpool clear' or replace the device with 'zpool replace'.
   see: http://www.sun.com/msg/ZFS-8000-9P
  scan: scrub repaired 0 in 0h1m with 0 errors on Wed May 29 03:01:09 2013
config:

        NAME                                            STATE     READ WRITE CKSUM
        Zgroup1                                         ONLINE       0     0     0
          raidz1-0                                      ONLINE       0     0     0
            gptid/8224d758-7e41-11e2-9973-d43d7e4c95f2  ONLINE       0     0     0
            gptid/827b708a-7e41-11e2-9973-d43d7e4c95f2  ONLINE       0     0     0
            gptid/82d076b6-7e41-11e2-9973-d43d7e4c95f2  ONLINE       0     0     0
          raidz1-1                                      ONLINE       0     0     0
            gptid/e36dd6dd-a7ab-11e2-b159-d43d7e4c95f2  ONLINE       0     0     0
            gptid/14c980b1-a7d3-11e2-8a48-d43d7e4c95f2  ONLINE       0     0     0
            gptid/6938e3a2-9e4b-11e2-b093-d43d7e4c95f2  ONLINE       0     0     1

errors: No known data errors

smartcl -a /dev/ada5

Code:

smartctl -a /dev/ada5
smartctl 5.43 2012-06-30 r3573 [FreeBSD 8.3-RELEASE-p5 amd64] (local build)
Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net

=== START OF INFORMATION SECTION ===
Device Model:     WDC WD20EFRX-68AX9N0
Serial Number:    WD-WMC301410766
LU WWN Device Id: 5 0014ee 6033297a3
Firmware Version: 80.00A80
User Capacity:    2,000,398,934,016 bytes [2.00 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 May 30 18:21:34 2013 PDT
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:                (27720) 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:        ( 280) minutes.
Conveyance self-test routine
recommended polling time:        (   5) minutes.
SCT capabilities:              (0x70bd) 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       -       0
  3 Spin_Up_Time            0x0027   180   178   021    Pre-fail  Always       -       3983
  4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       13
  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   099   099   000    Old_age   Always       -       1316
 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       -       11
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       7
193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       5
194 Temperature_Celsius     0x0022   110   099   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   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
ATA Error Count: 50 (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 50 occurred at disk power-on lifetime: 1001 hours (41 days + 17 hours)
  When the command that caused the error occurred, the device was doing SMART Offline or Self-test.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  04 61 10 90 02 40 e0  Device Fault; Error: ABRT 16 sectors at LBA = 0x00400290 = 4194960

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  c8 00 10 90 02 40 e0 00  29d+14:52:36.347  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.347  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA

Error 49 occurred at disk power-on lifetime: 1001 hours (41 days + 17 hours)
  When the command that caused the error occurred, the device was doing SMART Offline or Self-test.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  04 61 10 90 02 40 e0  Device Fault; Error: ABRT 16 sectors at LBA = 0x00400290 = 4194960

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  c8 00 10 90 02 40 e0 00  29d+14:52:36.347  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA

Error 48 occurred at disk power-on lifetime: 1001 hours (41 days + 17 hours)
  When the command that caused the error occurred, the device was doing SMART Offline or Self-test.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  04 61 10 90 02 40 e0  Device Fault; Error: ABRT 16 sectors at LBA = 0x00400290 = 4194960

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA

Error 47 occurred at disk power-on lifetime: 1001 hours (41 days + 17 hours)
  When the command that caused the error occurred, the device was doing SMART Offline or Self-test.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  04 61 10 90 02 40 e0  Device Fault; Error: ABRT 16 sectors at LBA = 0x00400290 = 4194960

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA

Error 46 occurred at disk power-on lifetime: 1001 hours (41 days + 17 hours)
  When the command that caused the error occurred, the device was doing SMART Offline or Self-test.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  04 61 10 90 02 40 e0  Device Fault; Error: ABRT 16 sectors at LBA = 0x00400290 = 4194960

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  c8 00 10 90 02 40 e0 00  29d+14:52:36.346  READ DMA

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%      1295         -
# 2  Short offline       Completed without error       00%      1271         -
# 3  Short offline       Completed without error       00%      1247         -
# 4  Short offline       Completed without error       00%      1223         -
# 5  Short offline       Completed without error       00%      1199         -
# 6  Short offline       Completed without error       00%      1167         -
# 7  Short offline       Completed without error       00%      1143         -
# 8  Short offline       Completed without error       00%      1119         -
# 9  Short offline       Completed without error       00%      1095         -
#10  Short offline       Completed without error       00%      1071         -
#11  Extended offline    Completed without error       00%      1047         -
#12  Short offline       Aborted by host               10%      1001         -
#13  Short offline       Completed without error       00%       961         -
#14  Short offline       Completed without error       00%       937         -
#15  Short offline       Completed without error       00%       913         -
#16  Short offline       Completed without error       00%       889         -
#17  Short offline       Completed without error       00%       865         -
#18  Short offline       Completed without error       00%       841         -
#19  Short offline       Completed without error       00%       817         -
#20  Short offline       Completed without error       00%       793         -
#21  Short offline       Completed without error       00%       769         -

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.

I have not issued the zpool clear command yet because I want to wait and get feedback from the forums before doing anything this time.

Has anyone else had this issue or have any idea what the problem maybe.

 

[William Grzybowski]

It is not zpool scrub that is causing it to get corrupted. Quite the opposite, it is avoiding your pool to get corrupted.

You may be suffering from silent bit rot. One block of one of the disks had corrupted data.

It is possible that port of your controller is not behaving as expected.

 

[Caesar]

I agree that the cause is not the scrub but the issue isnt found until a scrub is performed and then I cannot find anything wrong with the disk after the zpool clear. Do you think it would be a good test to swap the drive on this sata port with another drive on another port. Then if the issue follows the drive we know that the port is not the problem.

 

[titan_rw]

Yes, I would switch ports. But leave the cables where they are. So if you have port A, going to cable A, to drive A, and B to B to B, then change it to port A - cable A to drive B. And port B to cable B to drive A.

Then if any subsequent checksum errors remain on the same line, I would strongly suspect the drive. If a different drive shows errors, then it's either the port, or cable.

 

[frank3523]

I had the same problem. After clearing the error a few day later the errors were there again.
Then a few days later my disk was failed. Relaced the failed disk and all errors are gone now.
So I think you have a disk that is having problems.

 

[paleoN]

Checksum errors are a sign of a problem. Note the offending disk, clear the errors and keep an eye on it. If they keep increasing make sure to find and resolve the problem. Don't wait until something breaks.

So I think you have a disk that is having problems.

Sometimes, but not always.

 

[Caesar]

ok so I am pretty sure its the disk now. I change the port and the same disk on the new port is getting the cksum errors. also it's getting alot of errors now about 30 so far in a week. I've order the replacement drive so it should be here soon. Thanks for your help guys!