What’s wrong with the messages like “UnrecovData 10B8B BadCRC” and “failed command: READ FPDMA QUEUED” on Linux?

I keep seeing messages in dmesg as follows with “exception Emask 0x10” -> “SError: { UnrecovData 10B8B BadCRC }” -> “failed command: READ FPDMA QUEUED” -> “hard resetting link”:

[ 7395.936692] ata4.00: exception Emask 0x10 SAct 0xe000 SErr 0x280100 action 0x6 frozen
[ 7395.936701] ata4.00: irq_stat 0x08000000, interface fatal error
[ 7395.936703] ata4: SError: { UnrecovData 10B8B BadCRC }
[ 7395.936705] ata4.00: failed command: READ FPDMA QUEUED
[ 7395.936708] ata4.00: cmd 60/00:68:20:7c:b0/04:00:7c:00:00/40 tag 13 ncq 524288 in
         res 40/00:78:20:84:b0/00:00:7c:00:00/40 Emask 0x10 (ATA bus error)
[ 7395.936709] ata4.00: status: { DRDY }
[ 7395.936710] ata4.00: failed command: READ FPDMA QUEUED
[ 7395.936712] ata4.00: cmd 60/00:70:20:80:b0/04:00:7c:00:00/40 tag 14 ncq 524288 in
         res 40/00:78:20:84:b0/00:00:7c:00:00/40 Emask 0x10 (ATA bus error)
[ 7395.936713] ata4.00: status: { DRDY }
[ 7395.936714] ata4.00: failed command: READ FPDMA QUEUED
[ 7395.936715] ata4.00: cmd 60/e0:78:20:84:b0/03:00:7c:00:00/40 tag 15 ncq 507904 in
         res 40/00:78:20:84:b0/00:00:7c:00:00/40 Emask 0x10 (ATA bus error)
[ 7395.936716] ata4.00: status: { DRDY }
[ 7395.936719] ata4: hard resetting link
[ 7396.241404] ata4: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[ 7396.243180] ata4.00: configured for UDMA/133
[ 7396.243195] ata4: EH complete

It seems are disks related warnings/errors.

ata4 seems the disk sdd:

# ls -l /sys/class/block/ | grep ata4
lrwxrwxrwx 1 root root 0 May  5 15:04 sdd -> ../../devices/pci0000:00/0000:00:1f.2/ata4/host3/target3:0:0/3:0:0:0/block/sdd
lrwxrwxrwx 1 root root 0 May  5 15:04 sdd1 -> ../../devices/pci0000:00/0000:00:1f.2/ata4/host3/target3:0:0/3:0:0:0/block/sdd/sdd1

The smartctl checking on sdd shows:

# smartctl -a /dev/sdd
smartctl 6.2 2014-07-16 r3952 [x86_64-linux-3.17.8-200.fc20.x86_64] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Seagate Barracuda 7200.14 (AF)
Device Model:     ST2000DM001-1CH164
Serial Number:    .........
LU WWN Device Id: 5 000c50 072c9ba25
Firmware Version: CC29
User Capacity:    2,000,398,934,016 bytes [2.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    7200 rpm
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-2, ACS-3 T13/2161-D revision 3b
SATA Version is:  SATA 3.1, 6.0 Gb/s (current: 3.0 Gb/s)
Local Time is:    Tue May  5 15:08:13 2015 CST
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: 		(  600) 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: 	 ( 225) minutes.
Conveyance self-test routine
recommended polling time: 	 (   2) minutes.
SCT capabilities: 	       (0x3085)	SCT Status 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   119   099   006    Pre-fail  Always       -       229791872
  3 Spin_Up_Time            0x0003   096   096   000    Pre-fail  Always       -       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age   Always       -       7
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000f   073   060   030    Pre-fail  Always       -       21876240
  9 Power_On_Hours          0x0032   097   097   000    Old_age   Always       -       3330
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always       -       6
183 Runtime_Bad_Block       0x0032   099   099   000    Old_age   Always       -       1
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       -       3 3 3
189 High_Fly_Writes         0x003a   100   100   000    Old_age   Always       -       0
190 Airflow_Temperature_Cel 0x0022   070   064   045    Old_age   Always       -       30 (Min/Max 29/31)
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       -       6
193 Load_Cycle_Count        0x0032   060   060   000    Old_age   Always       -       81321
194 Temperature_Celsius     0x0022   030   040   000    Old_age   Always       -       30 (0 22 0 0 0)
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       -       5
240 Head_Flying_Hours       0x0000   100   253   000    Old_age   Offline      -       2784h+08m+57.117s
241 Total_LBAs_Written      0x0000   100   253   000    Old_age   Offline      -       8817986301
242 Total_LBAs_Read         0x0000   100   253   000    Old_age   Offline      -       18410704178

SMART Error Log Version: 1
No Errors Logged

SMART Self-test log structure revision number 1
No self-tests have been logged.  [To run self-tests, use: smartctl -t]


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 results seem fine. What’s wrong on this server as indicated by the messages from dmesg?

Found some good sources of information related to ata error messages and some useful tips.

Understanding these messages

DRDY: Device ready. Normally 1, when all is OK.
UnrecovData: Data integrity error occurred, interface did not recover
BadCRC: Link layer CRC error occurred

Reference: Libata error messages

Possible reasons

An example:

ata3.00: exception Emask 0x50 SAct 0x1 SErr 0x280900 action 0x6 frozen
ata3.00: irq_stat 0x08000000, interface fatal error
ata3: SError: { 10B8B BadCRC } often may also include DisPar, UnrecovData, and/or HostInt

From an expert:

“Your machine seems to be suffering genuine link layer problem. In most cases, this indicates hardware problem and in my experience, common causes are (in the order of ballpark frequency)…

# inadequate power supply
# device and controller don’t like each other on 3Gbps
# cable too long or flaky connector (especially with eSATA cables or genders or backplanes)
# faulty controller or drive”

— tejun ( http://lkml.org/lkml/2008/12/2/426 ) (written by one of the foremost experts)

The presence of BadCRC is a pretty good indicator of a poor quality SATA cable. However, if a better cable does not solve the issue, then it is probably a power problem (loose power cable or backplane connection, poor connectors, poor power splitter, overloaded power supply, too many drives on power rail, bad power supply, etc).

Reference: The Analysis of Drive Issues