Write errors during pool extend - what do I do now?

TrueNAS General
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1

I have a system currently running SCALE ElectricEel-24.10.2., built about 6 months ago with 5x 4TB WD Red Plus drives (WD40EFPX) in a single pool. We are adding another 3 drives (same model) with an HBA (LSI 9200-8I). Using the new “extend” feature in 24.10 to add these three drives to the pool.

Full system details:

Summary
  • Intel Core i7-3770, Asus Sabretooth Z77
    ** 5x WD Red Plus 4TB (Original Pool “DOLLY-ARRAY”)
    ** 2x 120GB SATA SSD (boot drives, mirrored) (one is Intel 320 Series, the other is Patriot Burst Elite)
    ** 240GB Kingston NVMe SSD (Cache drive for pool)
    ** LSI SAS HBA 9200-8i
    *** 3x WD Red Plus (new drives for pool)

First drive added to the pool without any issues, took about 18-20 hours. Second drive ran for a couple hours then paused - TrueNas web UI shows the job “paused for resilver or clear” and an alert:

Critical
Pool DOLLY-ARRAY state is ONLINE: One or more devices has experienced an unrecoverable error. An attempt was made to correct the error. Applications are unaffected.
2025-03-12 12:20:59 (America/Los_Angeles)

Did some digging online, ran zpool status and found that one of the new drives had 6 write errors. Grabbed smart info with smartctl, ran a short smart test, did not see anything amiss. Decided to zpool clear and let the expand job continue to see if it would alert again - it did, about an hour or two later, one more write error.

Current output of zpool status:

admin@DOLLY[~]$ sudo zpool status -LP DOLLY-ARRAY
[sudo] password for admin: 
  pool: DOLLY-ARRAY
 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: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-9P
  scan: scrub repaired 0B in 04:48:32 with 0 errors on Tue Mar 11 16:03:01 2025
expand: expansion of raidz2-0 in progress since Tue Mar 11 11:15:45 2025
        2.14T / 11.2T copied at 25.0M/s, 19.14% done, paused for resilver or clear
config:

        NAME           STATE     READ WRITE CKSUM
        DOLLY-ARRAY    ONLINE       0     0     0
          raidz2-0     ONLINE       0     0     0
            /dev/sde1  ONLINE       0     0     0
            /dev/sdg1  ONLINE       0     0     0
            /dev/sdi1  ONLINE       0     0     0
            /dev/sdc1  ONLINE       0     0     0
            /dev/sdh1  ONLINE       0     0     0
            /dev/sda1  ONLINE       0     0     0
            /dev/sdb1  ONLINE       0     1     0
        cache
          /dev/sdj1    ONLINE       0     0     0

errors: No known data errors
admin@DOLLY[~]$

Current SMART status:

admin@DOLLY[~]$ sudo smartctl -a /dev/sdb   
smartctl 7.4 2023-08-01 r5530 [x86_64-linux-6.6.44-production+truenas] (local build)
Copyright (C) 2002-23, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Device Model:     WDC WD40EFPX-68C6CN0
Serial Number:    WD-WX22DA411C81
LU WWN Device Id: 5 0014ee 26be6e8b4
Firmware Version: 81.00A81
User Capacity:    4,000,787,030,016 bytes [4.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    5400 rpm
Form Factor:      3.5 inches
Device is:        Not in smartctl database 7.3/5528
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:    Wed Mar 12 12:18:59 2025 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:                (39840) 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:        ( 414) minutes.
Conveyance self-test routine
recommended polling time:        (   5) minutes.
SCT capabilities:              (0x3039) 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   204   204   021    Pre-fail  Always       -       2758
  4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       22
  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   100   100   000    Old_age   Always       -       50
 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       -       21
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       19
193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       59
194 Temperature_Celsius     0x0022   112   108   000    Old_age   Always       -       35
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   100   253   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  Short offline       Completed without error       00%        47         -
# 2  Extended offline    Aborted by host               90%        46         -

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.

The above only provides legacy SMART information - try 'smartctl -x' for more

admin@DOLLY[~]$

I think what I’d like to do now is stop the extend task (How do I do this? Is it possible?) and run the extended SMART test on the two remaining drives. (I realize now I ought to have tested the drives before adding them to the pool.) Or, another option, per the “action” suggested by zpool - could I zpool replace to the remaining, unused drive, and then would the “extend” job move to the replacement drive?

Thank you so much in advance for any guidance you can offer!

2

Thanks for the detailed info which will give us a fast start.

  • The pool is NOT degraded.

  • The SMART data doesn’t indicate any issues.

  • AFAIK you cannot stop an expansion once started.

So my advice is to wait until the expansion has finished, then run a scrub and once it completes run zpool status -v to see whether it corrected the unrecoverable write or not.

If the scrub runs clear, then do zpool clear to clear the one error and wait to see whether it was just a one-off glitch or whether something recurs.

2 Likes
3

The expansion is “paused” right now because of the error - is there a way to tell it to continue anyways? Or would I have to ‘zpool clear’ every time it hits an error?

4

Ah - I hadn’t spotted that.

If it were me I would run a SMART long test on /dev/sdb (the error drive) to see whether it completes cleanly. I might then do a scrub as well, and see whether that runs cleanly before doing a zpool clear and resuming the expansion.

5

Extended offline test for sdb came back with no errors, resuming expansion. Will update when complete.

1 Like
6

Expansion stopped again, 6 write errors on that same drive. I guess I don’t understand what the ‘write error’ indicates - how come they show up but the smart test is clean?
I am scrubbing the pool now - if I understand correctly, maybe there is an issue with the data being copied?

7

scrub repaired 0B in 06:17:49 with 0 errors on Tue Mar 18 18:26:00 2025

It’s about halfway through the expansion at this point.

8

The drive encountered an issue writing the data (check with smartctl) but managed to safely write the data (possibly reallocating sectors in the process). It’s doing its best, but is not healthy.
ZFS determined that data was not corrupted, but you should plan for a further resilver when replacing the drive…

9

Okay - the latest from zpool status is a bit worse:

admin@DOLLY[~]$ sudo zpool status -LP DOLLY-ARRAY
[sudo] password for admin: 
  pool: DOLLY-ARRAY
 state: DEGRADED
status: One or more devices are faulted in response to persistent errors.
        Sufficient replicas exist for the pool to continue functioning in a
        degraded state.
action: Replace the faulted device, or use 'zpool clear' to mark the device
        repaired.
  scan: scrub repaired 0B in 06:17:49 with 0 errors on Tue Mar 18 18:26:00 2025
expand: expansion of raidz2-0 in progress since Tue Mar 11 11:15:45 2025
        6.03T / 11.0T copied at 9.07M/s, 54.69% done, paused for resilver or clear
config:

        NAME           STATE     READ WRITE CKSUM
        DOLLY-ARRAY    DEGRADED     0     0     0
          raidz2-0     DEGRADED     0     0     0
            /dev/sde1  ONLINE       0     0     0
            /dev/sdg1  ONLINE       0     0     0
            /dev/sdi1  ONLINE       0     0     0
            /dev/sdc1  ONLINE       0     0     0
            /dev/sdh1  ONLINE       0     0     0
            /dev/sda1  ONLINE       0     0     0
            /dev/sdb1  FAULTED      0   257     0  too many errors
        cache
          /dev/sdj1    ONLINE       0     0     0

errors: No known data errors

So, at this point I’d definitely like to replace the drive with the spare I haven’t yet used. Since the drive is in the middle of being expanded onto, can I replace it in my pool without affecting the expand job?

10

As before, expansion will pause while replacing/resilvering and should automagically resume when it’s done.

2 Likes
11

There is no way to stop an expansion. It will pause while you resolve your faulty disk issue.