Pending sectors in valid array - how to proceed?

Pending sectors in valid array - how to proceed?

[Stefan G. Weichinger]

Greets,

in a customer-server I run these arrays:

# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4]
md1 : active raid1 sdb1[1] sda1[0]
      104320 blocks [2/2] [UU]

md3 : active raid5 sdd3[3](S) sdc3[2] sdb3[1] sda3[0]
      15647104 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]

md4 : active raid5 sdd4[3](S) sdc4[2] sdb4[1] sda4[0]
      471941376 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]


So far everything OK.

--

smartctl shows for /dev/sdb:

  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always
      -       0
195 Hardware_ECC_Recovered  0x001a   058   039   000    Old_age   Always
      -       146754005
197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always
      -       13
198 Offline_Uncorrectable   0x0010   100   100   000    Old_age
Offline      -       13

(relevant lines as far as I understand ...)

So I have these 13 pending sectors ...

I assume it would be good to swap sdb for safety?

This would mean:

* fail sdb

* wait for the spare to be synced ... which I fear somehow (I once lost
an array as a second drive dropped out while resync ...)

* change sdb

* re-add sdb

correct?

I also read of a way of removing and re-adding a drive to get rid of
these sectors?

Is this a recommended thing to do?
What would you recommend me to do?

Thank you, Stefan

Re: Pending sectors in valid array - how to proceed?

[Tim Small]

Stefan G. Weichinger wrote:
> md3 : active raid5 sdd3[3](S) sdc3[2] sdb3[1] sda3[0]
>       15647104 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]
>   

...

> smartctl shows for /dev/sdb:
>
>   5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always
>       -       0
> 195 Hardware_ECC_Recovered  0x001a   058   039   000    Old_age   Always
>       -       146754005
> 197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always
>       -       13
> 198 Offline_Uncorrectable   0x0010   100   100   000    Old_age
> Offline      -       13
>
> (relevant lines as far as I understand ...)
>   

Do you have any high-fly writes?  Are there lots of
Hardware_ECC_Recovered on all the drives?  Is vibration likely to be an
issue?  What's the drive/chassis?
> I also read of a way of removing and re-adding a drive to get rid of
> these sectors?
>
> Is this a recommended thing to do?
> What would you recommend me to do?
>   

I think you should trigger a check, this should attempt to read these
pending sectors (assuming they are within the boundaries of the array),
along with every other sector in the array, and scrub them when the read
fails (i.e. reconstruct the data from the other array members, and write
them to the pending sectors on sdb - thus triggering reallocation of
those sectors).

echo check > /sys/block/md1/md/sync_action

etc.

Personally, I'd then wait to see if/how the reallocated count goes up -
if the sectors are the result of a one-off event, then no-problem, but
if they steadily climb, then the drive is probably on its way out -
those ECC_Recovered counts look a bit naff to me.  If you're nervous of
losing a drive during resync, the the check is a good thing to do first,
but you could also consider migrating the array to RAID6, to give you
double redundancy...

Cheers,

Tim.

Re: Pending sectors in valid array - how to proceed?

[Stefan *St0fF* Huebner]

 Am 28.07.2010 20:41, schrieb Tim Small:
> Stefan G. Weichinger wrote:
>> md3 : active raid5 sdd3[3](S) sdc3[2] sdb3[1] sda3[0]
>>       15647104 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]
>>   
> ...
>
>> smartctl shows for /dev/sdb:
>>
>>   5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always
>>       -       0
>> 195 Hardware_ECC_Recovered  0x001a   058   039   000    Old_age   Always
>>       -       146754005
>> 197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always
>>       -       13
>> 198 Offline_Uncorrectable   0x0010   100   100   000    Old_age
>> Offline      -       13
>>
>> (relevant lines as far as I understand ...)
>>   
> Do you have any high-fly writes?  Are there lots of
> Hardware_ECC_Recovered on all the drives?  Is vibration likely to be an
> issue?  What's the drive/chassis?
Hardware ECC recovered means how many times the internal error
correction of the drive succeeded.  Indeed this may indicate vibration
or other external sources of errors.
>> I also read of a way of removing and re-adding a drive to get rid of
>> these sectors?
>>
>> Is this a recommended thing to do?
>> What would you recommend me to do?
>>   
> I think you should trigger a check, this should attempt to read these
> pending sectors (assuming they are within the boundaries of the array),
> along with every other sector in the array, and scrub them when the read
> fails (i.e. reconstruct the data from the other array members, and write
> them to the pending sectors on sdb - thus triggering reallocation of
> those sectors).
>
> echo check > /sys/block/md1/md/sync_action
Well, I also think this would be the way to go, but it depends on the
drives used!!!  Are the drives Customer Class or Enterprise Class
drives?  If they are Enterprise Class (i.e. Raid Edition), go ahead.  If
they're Customer Class, please enable ERC (if supported by the drives)
before scrubbing, as this needs to be there.  If ERC is not supported
(or not enabled), most likely when hitting a pending sector, the
respective drive will not respond while doing it's error correction.  It
will still be in the error recovery procedure, when mdraid tries to
rewrite the sector.  The rewrite will fail, as the drive won't respond. 
Then the drive gets kicked out of the array.
> etc.
>
> Personally, I'd then wait to see if/how the reallocated count goes up -
> if the sectors are the result of a one-off event, then no-problem, but
> if they steadily climb, then the drive is probably on its way out -
> those ECC_Recovered counts look a bit naff to me.  If you're nervous of
> losing a drive during resync, the the check is a good thing to do first,
> but you could also consider migrating the array to RAID6, to give you
> double redundancy...
I have had the situation, that pending sectors just went away ;)  No
reallocation occurred.  I just wanted to mention that this might be
another way it can go so you're not surprised if that happens.
> Cheers,
>
> Tim.
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dito,
Stefan

Re: Pending sectors in valid array - how to proceed?

[Roman Mamedov]

[-- Attachment #1: Type: text/plain, Size: 1253 bytes --]

On Wed, 28 Jul 2010 22:27:48 +0200
Stefan *St0fF* Huebner <st0ff@gmx.net> wrote:

> >>   5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always
> >>       -       0
> >> 195 Hardware_ECC_Recovered  0x001a   058   039   000    Old_age   Always
> >>       -       146754005
> >> 197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always
> >>       -       13
> >> 198 Offline_Uncorrectable   0x0010   100   100   000    Old_age
> >> Offline      -       13
> >>
> >> (relevant lines as far as I understand ...)
> >>   
> > Do you have any high-fly writes?  Are there lots of
> > Hardware_ECC_Recovered on all the drives?  Is vibration likely to be an
> > issue?  What's the drive/chassis?
> Hardware ECC recovered means how many times the internal error
> correction of the drive succeeded.  Indeed this may indicate vibration
> or other external sources of errors.

That drive is most likely a Seagate, and if so, there's nothing to worry
about. Literally every Seagate drive will have a high value in
Hardware_ECC_Recovered, it's just a peculiarity of their SMART. Other vendors'
drives recover read errors using ECC too, but don't report that into the SMART
metric.

-- 
With respect,
Roman

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Re: Pending sectors in valid array - how to proceed?

[Simon Matthews]

On Wed, Jul 28, 2010 at 2:11 PM, Roman Mamedov <roman@rm.pp.ru> wrote:
> On Wed, 28 Jul 2010 22:27:48 +0200
> Stefan *St0fF* Huebner <st0ff@gmx.net> wrote:
>
>> >>   5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always
>> >>       -       0
>> >> 195 Hardware_ECC_Recovered  0x001a   058   039   000    Old_age   Always
>> >>       -       146754005
>> >> 197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always
>> >>       -       13
>> >> 198 Offline_Uncorrectable   0x0010   100   100   000    Old_age
>> >> Offline      -       13
>> >>
>> >> (relevant lines as far as I understand ...)
>> >>
>> > Do you have any high-fly writes?  Are there lots of
>> > Hardware_ECC_Recovered on all the drives?  Is vibration likely to be an
>> > issue?  What's the drive/chassis?
>> Hardware ECC recovered means how many times the internal error
>> correction of the drive succeeded.  Indeed this may indicate vibration
>> or other external sources of errors.
>
> That drive is most likely a Seagate, and if so, there's nothing to worry
> about. Literally every Seagate drive will have a high value in
> Hardware_ECC_Recovered, it's just a peculiarity of their SMART. Other vendors'
> drives recover read errors using ECC too, but don't report that into the SMART
> metric.
>

I am waiting for this drive to get to the point that Seagate will accept an RMA:

ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE
UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000f   089   076   006    Pre-fail
Always       -       173224741
  3 Spin_Up_Time            0x0003   094   093   000    Pre-fail
Always       -       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age
Always       -       69
  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail
Always       -       2002
  7 Seek_Error_Rate         0x000f   046   036   030    Pre-fail
Always       -       42786857552386
  9 Power_On_Hours          0x0032   082   082   000    Old_age
Always       -       16170
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail
Always       -       5
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age
Always       -       69
184 Unknown_Attribute       0x0032   100   100   099    Old_age
Always       -       0
187 Reported_Uncorrect      0x0032   012   012   000    Old_age
Always       -       88
188 Unknown_Attribute       0x0032   100   090   000    Old_age
Always       -       112
189 High_Fly_Writes         0x003a   100   100   000    Old_age
Always       -       0
190 Airflow_Temperature_Cel 0x0022   064   057   045    Old_age
Always       -       36 (Lifetime Min/Max 33/43)
194 Temperature_Celsius     0x0022   036   043   000    Old_age
Always       -       36 (0 10 0 0)
195 Hardware_ECC_Recovered  0x001a   031   020   000    Old_age
Always       -       173224741
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


It is a desktop drive and is used for half of several  RAID1 arrays,
but so far it hasn't been kicked out of any arrays. I have run a check
several times in the last few days.  I had expected it to show a
failing state when the reallocated sector count reached 2000, but it
hasn't.

The Seek Error rate is an order of magnitude higher than an identical
drive that is the other half of those RAID1 arrays:

ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE
UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000f   108   091   006    Pre-fail
Always       -       31895651
  3 Spin_Up_Time            0x0003   094   093   000    Pre-fail
Always       -       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age
Always       -       55
  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail
Always       -       0
  7 Seek_Error_Rate         0x000f   056   051   030    Pre-fail
Always       -       3741314243502
  9 Power_On_Hours          0x0032   082   082   000    Old_age
Always       -       16221
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail
Always       -       2
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age
Always       -       55
184 Unknown_Attribute       0x0032   100   100   099    Old_age
Always       -       0
187 Reported_Uncorrect      0x0032   049   049   000    Old_age
Always       -       51
188 Unknown_Attribute       0x0032   100   098   000    Old_age
Always       -       2
189 High_Fly_Writes         0x003a   100   100   000    Old_age
Always       -       0
190 Airflow_Temperature_Cel 0x0022   059   051   045    Old_age
Always       -       41 (Lifetime Min/Max 39/49)
194 Temperature_Celsius     0x0022   040   049   000    Old_age
Always       -       40 (0 9 0 0)
195 Hardware_ECC_Recovered  0x001a   025   015   000    Old_age
Always       -       31895651
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   192   000    Old_age
Always       -       15



Simon
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Re: Pending sectors in valid array - how to proceed?

[Stefan G. Weichinger]

Am 28.07.2010 23:11, schrieb Roman Mamedov:

> That drive is most likely a Seagate, and if so, there's nothing to worry
> about. Literally every Seagate drive will have a high value in
> Hardware_ECC_Recovered, it's just a peculiarity of their SMART. Other vendors'
> drives recover read errors using ECC too, but don't report that into the SMART
> metric.

Yep, it's a Seagate.

All four are Seagate:

sda, sdb: ST3250310NS  (should have ERC as far as I found online)
sdc, sdd: ST3250621NS  (still don't know if they have ERC)

I now decided to run that check-action on all three arrays.

So far it looks good. All three arrays re-synced OK, without any drive
failing. Good :-)

Still no reallocated sectors on all four drives.

"Current_Pending_Sector" and "Offline_Uncorrectable" on /dev/sdb still
at the old value of "13".

Do you think I should swap that drive or not?

(added difficulty: that server is around 400km from me ... I would have
to direct an employee there to swap the hdd ...)

Migrating to RAID6, sure, would make sense, but this would need a
kernel-upgrade and involves quite some work. Right now I have
2.6.25-gentoo-r7 there :-(

thank you all for your replies, Stefan

Re: Pending sectors in valid array - how to proceed?

[Simon Matthews]

On Wed, Jul 28, 2010 at 7:50 PM, Simon Matthews
<simon.d.matthews@gmail.com> wrote:

>
> I am waiting for this drive to get to the point that Seagate will accept an RMA:
>
> ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE
> UPDATED  WHEN_FAILED RAW_VALUE
>  1 Raw_Read_Error_Rate     0x000f   089   076   006    Pre-fail
> Always       -       173224741
>  3 Spin_Up_Time            0x0003   094   093   000    Pre-fail
> Always       -       0
>  4 Start_Stop_Count        0x0032   100   100   020    Old_age
> Always       -       69
>  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail
> Always       -       2002
>  7 Seek_Error_Rate         0x000f   046   036   030    Pre-fail
> Always       -       42786857552386
>  9 Power_On_Hours          0x0032   082   082   000    Old_age
> Always       -       16170
>  10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail
> Always       -       5
>  12 Power_Cycle_Count       0x0032   100   100   020    Old_age
> Always       -       69
> 184 Unknown_Attribute       0x0032   100   100   099    Old_age
> Always       -       0
> 187 Reported_Uncorrect      0x0032   012   012   000    Old_age
> Always       -       88
> 188 Unknown_Attribute       0x0032   100   090   000    Old_age
> Always       -       112
> 189 High_Fly_Writes         0x003a   100   100   000    Old_age
> Always       -       0
> 190 Airflow_Temperature_Cel 0x0022   064   057   045    Old_age
> Always       -       36 (Lifetime Min/Max 33/43)
> 194 Temperature_Celsius     0x0022   036   043   000    Old_age
> Always       -       36 (0 10 0 0)
> 195 Hardware_ECC_Recovered  0x001a   031   020   000    Old_age
> Always       -       173224741
> 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
>
>
> It is a desktop drive and is used for half of several  RAID1 arrays,
> but so far it hasn't been kicked out of any arrays. I have run a check
> several times in the last few days.  I had expected it to show a
> failing state when the reallocated sector count reached 2000, but it
> hasn't.


Well, despite the S.M.A.R.T. data showing that the drive is OK, it has
apparently totally failed this evening. The disk is totally
inaccessible

From the logs:
Jul 29 20:39:56 server2 kernel: ata1: failed to read log page 10h (errno=-5)
Jul 29 20:40:48 server2 kernel: ata1.00: exception Emask 0x1 SAct
0x403ffff7 SErr 0x0 action 0x0
Jul 29 20:40:48 server2 kernel: ata1.00: irq_stat 0x40000008
Jul 29 20:40:48 server2 kernel: ata1.00: cmd
60/80:00:e8:2b:5a/00:00:47:00:00/40 tag 0 ncq 65536 in
Jul 29 20:40:48 server2 kernel:          res
40/00:a8:e8:35:5a/3a:00:47:00:00/40 Emask 0x1 (device error)
Jul 29 20:40:48 server2 kernel: ata1.00: status: { DRDY }
Jul 29 20:40:48 server2 kernel: ata1.00: cmd
60/80:08:e8:2f:5a/00:00:47:00:00/40 tag 1 ncq 65536 in
Jul 29 20:40:48 server2 kernel:          res
40/00:a8:e8:35:5a/00:00:47:00:00/40 Emask 0x1 (device error)
Jul 29 20:40:48 server2 kernel: ata1.00: status: { DRDY }
Jul 29 20:40:48 server2 kernel: ata1.00: cmd
60/80:10:e8:33:5a/00:00:47:00:00/40 tag 2 ncq 65536 in
Jul 29 20:40:48 server2 kernel:          res
40/00:a8:e8:35:5a/00:00:47:00:00/40 Emask 0x1 (device error)
...
Jul 29 20:40:48 server2 kernel: ata1.00: status: { DRDY }
Jul 29 20:40:48 server2 kernel: ata1.00: qc timeout (cmd 0xec)
Jul 29 20:40:48 server2 kernel: ata1.00: failed to IDENTIFY (I/O
error, err_mask=0x5)
Jul 29 20:40:48 server2 kernel: ata1.00: revalidation failed (errno=-5)
Jul 29 20:40:48 server2 kernel: ata1: hard resetting link
Jul 29 20:40:48 server2 kernel: ata1: SATA link up 3.0 Gbps (SStatus
123 SControl 300)
Jul 29 20:40:48 server2 kernel: ata1.00: qc timeout (cmd 0xa1)
Jul 29 20:40:48 server2 kernel: ata1.00: failed to IDENTIFY (I/O
error, err_mask=0x5)
Jul 29 20:40:48 server2 kernel: ata1.00: revalidation failed (errno=-5)
Jul 29 20:40:48 server2 kernel: ata1: limiting SATA link speed to 1.5 Gbps
Jul 29 20:40:48 server2 kernel: ata1: hard resetting link
Jul 29 20:40:48 server2 kernel: ata1: SATA link up 1.5 Gbps (SStatus
113 SControl 310)
Jul 29 20:40:48 server2 kernel: ata1.00: qc timeout (cmd 0xa1)
Jul 29 20:40:48 server2 kernel: ata1.00: failed to IDENTIFY (I/O
error, err_mask=0x5)
Jul 29 20:40:48 server2 kernel: ata1.00: revalidation failed (errno=-5)
Jul 29 20:40:48 server2 kernel: ata1.00: disabled
Jul 29 20:40:48 server2 kernel: ata1: hard resetting link
Jul 29 20:40:48 server2 kernel: ata1: SATA link up 1.5 Gbps (SStatus
113 SControl 310)
Jul 29 20:40:48 server2 kernel: ata1: EH complete
Jul 29 20:40:48 server2 kernel: sd 0:0:0:0: [sda] Unhandled error code
Jul 29 20:40:48 server2 kernel: sd 0:0:0:0: [sda] Result:
hostbyte=0x04 driverbyte=0x00
Jul 29 20:40:48 server2 kernel: end_request: I/O error, dev sda,
sector 1197091688


I guess Seagate will accept it for an RMA now!

Simon
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