Disk activity with ZFS z2 array after install

[RaidPirate]

Noob question regarding disk activity I'm seeing with a 6 disk z2 array.

How long does it take before disk activity settles down?

After initially creating a pool my disks were active for a few minutes until the UI reported that the pool had been created.

The system has now been running for about 24 h, and there is still disk activity. Approx every 3-5 seconds, I hear a clicking sound as the disk heads move around... doing whatever it is that disk read/write heads do...

When this happens, activity LEDs light up on my HBA. Again, about once every 3 seconds or so.

Is this normal behaviour?

I was having issues previously with the pool reporting errors, indicating drive failure. However I was sceptical about this since these are new disks. So I started again and rebuilt the pool from scratch, this time not shutting down my system after creating the pool.

SCRUB is scheduled for Sunday midnight and the next SMART test is not due for about a week.

Is there any way to know what is causing this disk activity, for example with something like iotop?

 

[c77dk]

I have been hearing the same I believe - with me smart and scrub sees nothing wrong, so I've looked into the actual smart data, and found one of my IronWolfs having a value of 8590065666 for the "Command_Timeout" counter. Checking with the reports of disk busy I can see it has reported higher numbers than the rest.

The rest of my IronWolfs say 0 for the same counter, so time for RMA.

My advice would be to check the output from smart and see if there's something looking strange. Also - where's your system dataset residing? could be something as simple as logs/stats being written.

 

[RaidPirate]

I have been hearing the same I believe - with me smart and scrub sees nothing wrong, so I've looked into the actual smart data, and found one of my IronWolfs having a value of 8590065666 for the "Command_Timeout" counter. Checking with the reports of disk busy I can see it has reported higher numbers than the rest.

The rest of my IronWolfs say 0 for the same counter, so time for RMA.

My advice would be to check the output from smart and see if there's something looking strange. Also - where's your system dataset residing? could be something as simple as logs/stats being written.

Thanks for the info - I don't know about logs. I will check this.

Can you direct me to how I view these SMART logs? Is there any way to get the system to do a SMART test right "now"?

I found ways to do this with SATA connected drives. My drives are SATA, but connected via an IT mode HBA... The same commands don't appear to work?

 

[c77dk]

Can you direct me to how I view these SMART logs? Is there any way to get the system to do a SMART test right "now"?

You have to go to the commandline and run the folowing (replacing the "ada5" with the name of your disks)

Code:

smartctl -a /dev/ada5

 

[RaidPirate]

You have to go to the commandline and run the folowing (replacing the "ada5" with the name of your disks)

Code:

smartctl -a /dev/ada5

Thanks - really useful. I'm seeing this. I presume this means disk 6 is ok?

 

[masru]

The system has now been running for about 24 h, and there is still disk activity. Approx every 3-5 seconds, I hear a clicking sound as the disk heads move around... doing whatever it is that disk read/write heads do...

When this happens, activity LEDs light up on my HBA. Again, about once every 3 seconds or so.

Is this normal behaviour?

Yes, this is normal. and will stay that way.

 

[c77dk]

Thanks - really useful. I'm seeing this. I presume this means disk 6 is ok?

Yes - and no. "Yes" because it has managed to do a long scan, which i always good, "no" because even though the disk can do a long test and think everything is ok, you can have some disturbing values in the counters (the part you have omitted in the top)..

As an example you can look at this output from my drive

Code:

smartctl 7.1 2019-12-30 r5022 [FreeBSD 12.2-PRERELEASE amd64] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Seagate IronWolf
Device Model:     ST8000VN004-2M2101
Firmware Version: SC60
User Capacity:    8,001,563,222,016 bytes [8.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    7200 rpm
Form Factor:      3.5 inches
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-4 (minor revision not indicated)
SATA Version is:  SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Fri Oct  2 15:26:33 2020 CEST
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:         (  567) 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:      ( 742) minutes.
Conveyance self-test routine
recommended polling time:      (   2) minutes.
SCT capabilities:            (0x50bd)    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   074   064   044    Pre-fail  Always       -       24617641
  3 Spin_Up_Time            0x0003   082   082   000    Pre-fail  Always       -       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age   Always       -       12
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000f   079   060   045    Pre-fail  Always       -       84782912
  9 Power_On_Hours          0x0032   098   098   000    Old_age   Always       -       2225
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always       -       12
 18 Unknown_Attribute       0x000b   100   100   050    Pre-fail  Always       -       0
187 Reported_Uncorrect      0x0032   100   100   000    Old_age   Always       -       0
188 Command_Timeout         0x0032   100   099   000    Old_age   Always       -       8590065666
190 Airflow_Temperature_Cel 0x0022   061   051   040    Old_age   Always       -       39 (Min/Max 37/44)
192 Power-Off_Retract_Count 0x0032   100   100   000    Old_age   Always       -       0
193 Load_Cycle_Count        0x0032   100   100   000    Old_age   Always       -       148
194 Temperature_Celsius     0x0022   039   049   000    Old_age   Always       -       39 (0 28 0 0 0)
195 Hardware_ECC_Recovered  0x001a   074   064   000    Old_age   Always       -       24617641
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      -       2221 (100 56 0)
241 Total_LBAs_Written      0x0000   100   253   000    Old_age   Offline      -       22828812722
242 Total_LBAs_Read         0x0000   100   253   000    Old_age   Offline      -       40418358301

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%      2216         -
# 2  Short offline       Completed without error       00%      2186         -
# 3  Short offline       Completed without error       00%      2162         -
# 4  Short offline       Completed without error       00%      2138         -
# 5  Short offline       Completed without error       00%      2114         -
# 6  Short offline       Completed without error       00%      2090         -
# 7  Short offline       Completed without error       00%      2066         -
# 8  Short offline       Completed without error       00%      2042         -
# 9  Short offline       Completed without error       00%      2018         -
#10  Short offline       Completed without error       00%      1994         -
#11  Short offline       Completed without error       00%      1970         -
#12  Short offline       Completed without error       00%      1946         -
#13  Short offline       Completed without error       00%      1922         -
#14  Short offline       Completed without error       00%      1898         -
#15  Short offline       Completed without error       00%      1874         -
#16  Short offline       Completed without error       00%      1850         -
#17  Short offline       Completed without error       00%      1826         -
#18  Short offline       Completed without error       00%      1802         -
#19  Short offline       Completed without error       00%      1778         -
#20  Short offline       Completed without error       00%      1754         -
#21  Short offline       Completed without error       00%      1730         -

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.

SMART passes, but "188 Command_Timeout" value is crazy and causing disk to make a lot of noise.

 

[masru]

Can you direct me to how I view these SMART logs? Is there any way to get the system to do a SMART test right "now"?

You can start a smart test at any time on the command line.
For a short test type:

Code:

smartctl -t short /dev/ada0

This test will tell you how long it will take.

You can check the results of this self test (and about 10 of the last tests) on that drive with:

Code:

smartctl -l selftest /dev/ada0

Also, you can start a long test, which will read the whole drive with:

Code:

smartctl -t long /dev/ada0

This one will take some hours.

 

[HoneyBadger]

Approx every 3-5 seconds

This is the normal timeout period for a ZFS transaction group. Even with no outside write activity, ZFS will be writing some metadata and a transaction group update at least every five seconds. This is normal and expected behavior.

I have been hearing the same I believe - with me smart and scrub sees nothing wrong, so I've looked into the actual smart data, and found one of my IronWolfs having a value of 8590065666 for the "Command_Timeout" counter. Checking with the reports of disk busy I can see it has reported higher numbers than the rest.

The rest of my IronWolfs say 0 for the same counter, so time for RMA.

Seagate reports the RAW value for that counter, so you have to do some voodoo to figure out what it's actually saying.

8590065666 converted to HEX is 0x000200020002 - split into the three portions for this field is 0002 for each - but that means you've had two commands take longer than 7.5s to execute. Check the cables and monitor but I wouldn't say RMA is out of the question.

 

[sretalla]

It's probably worth noting that your system dataset will probably be on that pool if it's your only one other than the boot pool. (you can find/change that in the GUI under System | System Dataset )

Depending on your choice of boot media, (if it's SSD) you may want to move it back to the boot pool or to another pool which is SSD-based in order to avoid having your spinning disks doing writes all the time... I have a pool with 24 drives and they only show activity when I'm using files on that pool. My System dataset is on the SSD pool where I run my jails.