UFS Sticky disk?

B

balanga

How can I identify the reason that a disk seems to pause intermittently when being accessed? Could I use some program such as diskinfo() to identify/verify that this is actually happening?
 
I believe the only way to check things like that is sysutils/smartmontools.
Run smartctl -a /dev/adaX and check if your disk has some uncorrectable errors or reallocated blocks.
You can also run tests with -t short or -t long flags.
 
What do you mean by "intermittently"? 1 ms, 10 ms, 100 ms, 1 s, 10 s, 1 minute?

And do you mean disk, or do you mean file system?

What is the total workload on the disk? Perhaps you have one application running, and you are complaining about that one application getting pauses in disk response, but you are ignoring that other applications are also running and using their share (fair or not) of the disk.

We need way more detail. That's all in addition to what aragats said: It's also possible that the disk is unhealthy. That can take many forms, only some of which will be detected by SMART (a.k.a. smartmontools or smartctl). For example, there is a famous case of a data center cooling too well, and all disks going into "safety verify after write" mode, causing disk performance to become horrible; smartctl would have reported an unusually low temperature, but not that the disks are unhappy.
 
aragats said:
I believe the only way to check things like that is sysutils/smartmontools.
Run smartctl -a /dev/adaX and check if your disk has some uncorrectable errors or reallocated blocks.
You can also run tests with -t short or -t long flags.
Click to expand...

smartctl -a /dev/ada1

Code: 
smartctl 7.0 2018-12-30 r4883 [FreeBSD 12.1-RELEASE amd64] (local build)
Copyright (C) 2002-18, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Toshiba 2.5" HDD MK..61GSY[N]
Device Model:     TOSHIBA MK5061GSYN
Serial Number:    5195F2TYS
LU WWN Device Id: 5 000039 34698332c
Firmware Version: MH000C
User Capacity:    500,107,862,016 bytes [500 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    7200 rpm
Form Factor:      2.5 inches
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ATA8-ACS (minor revision not indicated)
SATA Version is:  SATA 2.6, 3.0 Gb/s (current: 3.0 Gb/s)
Local Time is:    Mon Feb 10 20:19:30 2020 UTC
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:  (0x02)    Offline data collection activity
                    was completed without error.
                    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:         (  120) seconds.
Offline data collection
capabilities:              (0x51) SMART execute Offline immediate.
                    No Auto Offline data collection support.
                    Suspend Offline collection upon new
                    command.
                    No Offline surface scan supported.
                    Self-test supported.
                    No 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:      ( 112) minutes.
SCT capabilities:            (0x003f)    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   100   100   050    Pre-fail  Always       -       0
  2 Throughput_Performance  0x0027   100   100   050    Pre-fail  Always       -       0
  3 Spin_Up_Time            0x0023   100   100   002    Pre-fail  Always       -       2299
  4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       5256
  5 Reallocated_Sector_Ct   0x0033   078   078   010    Pre-fail  Always       -       452
  7 Seek_Error_Rate         0x002f   100   100   050    Pre-fail  Always       -       0
  8 Seek_Time_Performance   0x0025   100   100   050    Pre-fail  Offline      -       0
  9 Power_On_Minutes        0x0032   075   075   000    Old_age   Always       -       167h+52m
 10 Spin_Retry_Count        0x0033   205   100   030    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       4844
183 Runtime_Bad_Block       0x0032   100   100   001    Old_age   Always       -       372
184 End-to-End_Error        0x0033   100   100   097    Pre-fail  Always       -       0
185 Unknown_Attribute       0x0032   100   100   001    Old_age   Always       -       65535
187 Reported_Uncorrect      0x0032   100   100   000    Old_age   Always       -       0
188 Command_Timeout         0x0032   100   095   000    Old_age   Always       -       223
189 High_Fly_Writes         0x003a   100   100   001    Old_age   Always       -       0
190 Airflow_Temperature_Cel 0x0022   069   044   040    Old_age   Always       -       31 (Min/Max 26/33)
191 G-Sense_Error_Rate      0x0032   100   100   000    Old_age   Always       -       47
192 Power-Off_Retract_Count 0x0022   100   100   000    Old_age   Always       -       10682531
193 Load_Cycle_Count        0x0032   092   092   000    Old_age   Always       -       83421
196 Reallocated_Event_Count 0x0032   100   100   000    Old_age   Always       -       34
197 Current_Pending_Sector  0x0032   100   100   000    Old_age   Always       -       0
199 UDMA_CRC_Error_Count    0x0032   200   200   000    Old_age   Always       -       0

SMART Error Log Version: 1
ATA Error Count: 1
    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 1 occurred at disk power-on lifetime: 4412 hours (183 days + 20 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
  -- -- -- -- -- -- --
  84 41 c0 6a 6d 16 60  Error: ICRC, ABRT at LBA = 0x00166d6a = 1469802

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  61 0b c0 60 6d 16 40 00      00:24:40.209  WRITE FPDMA QUEUED
  61 70 b8 c0 11 12 40 00      00:24:30.508  WRITE FPDMA QUEUED
  61 20 b0 a0 a3 be 40 00      00:24:30.508  WRITE FPDMA QUEUED
  61 20 a8 c0 03 c9 40 00      00:24:30.507  WRITE FPDMA QUEUED
  61 08 a0 20 cf 61 40 00      00:24:30.504  WRITE FPDMA QUEUED

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%     10006         -
# 2  Short offline       Completed without error       00%     10005         -
# 3  Short offline       Completed without error       00%      9985         -
# 4  Extended offline    Aborted by host               90%      8602         -
# 5  Short offline       Completed without error       00%      8602         -
# 6  Extended offline    Completed without error       00%      6263         -
# 7  Extended offline    Aborted by host               90%      6235         -
# 8  Short offline       Completed without error       00%      1636         -
# 9  Short offline       Completed without error       00%      1635         -
#10  Short offline       Completed without error       00%      1635         -
#11  Short offline       Completed without error       00%      1635         -
#12  Short offline       Completed without error       00%      1635         -
#13  Short offline       Completed without error       00%      1635         -
#14  Short offline       Completed without error       00%      1634         -
#15  Short offline       Completed without error       00%      1634         -
#16  Short offline       Completed without error       00%      1634         -
#17  Short offline       Completed without error       00%      1634         -
#18  Short offline       Completed without error       00%      1633         -
#19  Short offline       Completed without error       00%      1633         -
#20  Short offline       Completed without error       00%      1633         -
#21  Short offline       Completed without error       00%      1633         -

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 don't have much experience with such data analysis, however, Reallocated_Sector_Ct is far from 100 (a normalized value which means everything is okay).
Also, Spin_Retry_Count looks really strange to me: 205, which should be interpreted as "it's much better than it can be", but may be okay.
 
ralphbsz said:
What do you mean by "intermittently"? 1 ms, 10 ms, 100 ms, 1 s, 10 s, 1 minute?

We need way more detail.
Click to expand...

Unfortunately it seems to be quite subjective...I can be scrolling through a file list using misc/mc and all of a sudden there is no response and then it seems to work fine for some time and then suddenly stops for half a minute or more, and carries on normally for ten or fifteen minutes and then stops again. It's a disk I bought a couple of years ago, but found using it was problematic. I've just dug it out again and would like to find out if I can make it usable...
 
How do you know the problem is the disk? When the system is hung, can you see what it is doing? What state are the processes in? Is there disk access? Is the disk making noise (seeking)?

Strangely, the disk reports that it has only been used for 167 hours, so it is nearly unused (that's power on hours). My disks tend to have 50K hours, and they work fine. But the value of Reallocated_Sector_Ct is also a little worrying. It means 452 times a sector was so ill that the disk drive had to move it to another place. That's quite a high number.
 
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