Scrub and Checksum Question

R

riggieri

Dabbler
Joined
Aug 24, 2018
Messages
42
Hi Everyone

I recently got my server back online (was remodeling and server room was being built). The specs are below. I immediately ran a scrub. I got an email the next morning saying:

"The volume Volume01 state is ONLINE: One or more devices has experienced an unrecoverable error. An attempt was made to correct the error. Applications are unaffected."

So here is the pool status from right after the finished scrub .

Code:
NAME                                            STATE     READ WRITE CKSUM
    Volume01                                        ONLINE       0     0     0
      raidz2-0                                      ONLINE       0     0     0
        gptid/160ad1b3-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/17372117-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/18641503-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/19acedda-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/1aeff334-f744-11e8-a544-00259080c872  ONLINE       0     0     9  (repairing)
        gptid/1c1c5da9-f744-11e8-a544-00259080c872  ONLINE       0     0     0
      raidz2-1                                      ONLINE       0     0     0
        gptid/1d7d57ee-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/20b12a00-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/23955ed6-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/265a01d2-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/294c255b-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/2cf4b9bc-f744-11e8-a544-00259080c872  ONLINE       0     0     0
      raidz2-2                                      ONLINE       0     0     0
        gptid/e8dc4451-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/ea344686-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/eb1bc349-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/ec702641-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/edb8b034-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/eef56ec8-f89f-11e8-965b-00259080c872  ONLINE       0     0     0

errors: No known data errors


I then ran Short and long tests of the offending drive. No values were sticking out to me and both tests came back complete without errors.

Code:
smartctl 6.6 2017-11-05 r4594 [FreeBSD 11.1-STABLE amd64] (local build)
Copyright (C) 2002-17, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Device Model:     ST8000DM004-2CX188
Serial Number:    WCT0QXF5
LU WWN Device Id: 5 000c50 0ba1b6cec
Firmware Version: 0001
User Capacity:    8,001,563,222,016 bytes [8.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    5425 rpm
Form Factor:      3.5 inches
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   ACS-3 T13/2161-D revision 5
SATA Version is:  SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Mon Feb  4 12:20:57 2019 EST
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:         (    0) seconds.
Offline data collection
capabilities:              (0x73) SMART execute Offline immediate.
                    Auto Offline data collection on/off support.
                    Suspend Offline collection upon new
                    command.
                    No 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:      ( 975) minutes.
Conveyance self-test routine
recommended polling time:      (   2) minutes.
SCT capabilities:            (0x30a5)    SCT Status 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   076   064   006    Pre-fail  Always       -       37804480
  3 Spin_Up_Time            0x0003   093   091   000    Pre-fail  Always       -       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age   Always       -       31
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000f   077   061   045    Pre-fail  Always       -       47955113
  9 Power_On_Hours          0x0032   100   100   000    Old_age   Always       -       284 (211 239 0)
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always       -       31
183 Runtime_Bad_Block       0x0032   100   100   000    Old_age   Always       -       0
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   100   100   000    Old_age   Always       -       0
189 High_Fly_Writes         0x003a   100   100   000    Old_age   Always       -       0
190 Airflow_Temperature_Cel 0x0022   073   047   040    Old_age   Always       -       27 (Min/Max 15/33)
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       -       31
193 Load_Cycle_Count        0x0032   100   100   000    Old_age   Always       -       64
194 Temperature_Celsius     0x0022   027   053   000    Old_age   Always       -       27 (0 15 0 0 0)
195 Hardware_ECC_Recovered  0x001a   076   064   000    Old_age   Always       -       37804480
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      -       229 (161 129 0)
241 Total_LBAs_Written      0x0000   100   253   000    Old_age   Offline      -       60690732973
242 Total_LBAs_Read         0x0000   100   253   000    Old_age   Offline      -       71821424672

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%       274         -
# 2  Short offline       Completed without error       00%       259         -
# 3  Short offline       Completed without error       00%       181         -
# 4  Conveyance offline  Completed without error       00%       160         -
# 5  Short offline       Completed without error       00%       160         -

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.


So I cleared the zpool status and reran the scrub this morning. No Checksum errors.

Code:
pool: Volume01
 state: ONLINE
  scan: scrub repaired 0 in 0 days 04:58:11 with 0 errors on Mon Feb  4 12:34:24 2019
config:

    NAME                                            STATE     READ WRITE CKSUM
    Volume01                                        ONLINE       0     0     0
      raidz2-0                                      ONLINE       0     0     0
        gptid/160ad1b3-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/17372117-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/18641503-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/19acedda-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/1aeff334-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/1c1c5da9-f744-11e8-a544-00259080c872  ONLINE       0     0     0
      raidz2-1                                      ONLINE       0     0     0
        gptid/1d7d57ee-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/20b12a00-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/23955ed6-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/265a01d2-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/294c255b-f744-11e8-a544-00259080c872  ONLINE       0     0     0
        gptid/2cf4b9bc-f744-11e8-a544-00259080c872  ONLINE       0     0     0
      raidz2-2                                      ONLINE       0     0     0
        gptid/e8dc4451-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/ea344686-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/eb1bc349-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/ec702641-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/edb8b034-f89f-11e8-965b-00259080c872  ONLINE       0     0     0
        gptid/eef56ec8-f89f-11e8-965b-00259080c872  ONLINE       0     0     0

errors: No known data errors


So is this just ZFS doing it's thing and fixing corrupt data or is there something going on in my system? Should I do a Memory Test?

System Specs
Motherboard: X8DTi-F
Backplane: SAS2 6Gb/s Expander Backplane
Dual E5640L
96GB EEC DDR3 RAM
LSI 9210-8i HBA

Raidz-0 is made up of 8TB Seagate Drives. Issue was on DA05
Raidz-1 is 3TB HGST NAS Drives
Raidz-2 is a mix of 8TB HGST and 8TB Seagate Drives.

Thanks for your help and time.
 
A

Apollo

Wizard
Joined
Jun 13, 2013
Messages
1,458
Out of the blue like that it is difficult to understand the issue.
However, scrub did detect an issue and the power behind ZFS took care of detecting it and fixing it.
The reason could have been that your disk showing the error was either taken out of the pool for a while then upon reboot or something was reinstated causing data to be reevaluated and fixed.
Or maybe the disk got a bad sector causing the data to go bad. This should have been reported by the short or long test, maybe.
If you did turn your system off while data was being copied over, it is possible one of the disk didn't synchronize fully.
Maybe scrub never ran and the issue started from day one and the dat never got accessed until scrub took care of it.
Maybe you did upgrade Freenas and along the process, some glitch got in the way.

For now, I wouldn't worry too much, but I would certainly keep an eye on it.
 
R

riggieri

Dabbler
Joined
Aug 24, 2018
Messages
42
Hi Apollo

Thanks for the response. I will keep an eye on it and check my scrub reports.
 
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