Re: SMART: disk problems on RAIDZ1 pool: (ada6:ahcich6:0:0:0): CAM status: ATA Status Error

From: Rodney W. Grimes <freebsd-rwg_at_pdx.rh.CN85.dnsmgr.net>
Date: Tue, 12 Dec 2017 10:52:27 -0800 (PST)
> Hello,
> 
> running CURRENT (recent r326769), I realised that smartmond sends out some console
> messages when booting the box:
> 
> [...]
> Dec 12 14:14:33 <3.2> box1 smartd[68426]: Device: /dev/ada6, 1 Currently unreadable
> (pending) sectors Dec 12 14:14:33 <3.2> box1 smartd[68426]: Device: /dev/ada6, 1
> Offline uncorrectable sectors
> [...]
> 
> Checking the drive's SMART log with smartctl (it is one of four 3TB disk drives), I
> gather these informations:
> 
> [... smartctl -x /dev/ada6 ...]
> Error 42 [17] occurred at disk power-on lifetime: 25335 hours (1055 days + 15 hours)
>   When the command that caused the error occurred, the device was active or idle.
> 
>   After command completion occurred, registers were:
>   ER -- ST COUNT  LBA_48  LH LM LL DV DC
>   -- -- -- == -- == == == -- -- -- -- --
>   40 -- 51 00 00 00 00 c2 7a 72 98 40 00  Error: UNC at LBA = 0xc27a7298 = 3262804632
> 
>   Commands leading to the command that caused the error were:
>   CR FEATR COUNT  LBA_48  LH LM LL DV DC  Powered_Up_Time  Command/Feature_Name
>   -- == -- == -- == == == -- -- -- -- --  ---------------  --------------------
>   60 00 b0 00 88 00 00 c2 7a 73 20 40 08     23:38:12.195  READ FPDMA QUEUED
>   60 00 b0 00 80 00 00 c2 7a 72 70 40 08     23:38:12.195  READ FPDMA QUEUED
>   2f 00 00 00 01 00 00 00 00 00 10 40 08     23:38:12.195  READ LOG EXT
>   60 00 b0 00 70 00 00 c2 7a 73 20 40 08     23:38:09.343  READ FPDMA QUEUED
>   60 00 b0 00 68 00 00 c2 7a 72 70 40 08     23:38:09.343  READ FPDMA QUEUED
> [...]
> 
> and
> 
> [...]
> SMART Attributes Data Structure revision number: 16
> Vendor Specific SMART Attributes with Thresholds:
> ID# ATTRIBUTE_NAME          FLAGS    VALUE WORST THRESH FAIL RAW_VALUE
>   1 Raw_Read_Error_Rate     POSR-K   200   200   051    -    64
>   3 Spin_Up_Time            POS--K   178   170   021    -    6075
>   4 Start_Stop_Count        -O--CK   098   098   000    -    2406
>   5 Reallocated_Sector_Ct   PO--CK   200   200   140    -    0
>   7 Seek_Error_Rate         -OSR-K   200   200   000    -    0
>   9 Power_On_Hours          -O--CK   066   066   000    -    25339
>  10 Spin_Retry_Count        -O--CK   100   100   000    -    0
>  11 Calibration_Retry_Count -O--CK   100   100   000    -    0
>  12 Power_Cycle_Count       -O--CK   098   098   000    -    2404
> 192 Power-Off_Retract_Count -O--CK   200   200   000    -    154
> 193 Load_Cycle_Count        -O--CK   001   001   000    -    2055746
> 194 Temperature_Celsius     -O---K   122   109   000    -    28
> 196 Reallocated_Event_Count -O--CK   200   200   000    -    0
> 197 Current_Pending_Sector  -O--CK   200   200   000    -    1
> 198 Offline_Uncorrectable   ----CK   200   200   000    -    1
> 199 UDMA_CRC_Error_Count    -O--CK   200   200   000    -    0
> 200 Multi_Zone_Error_Rate   ---R--   200   200   000    -    5
>                             ||||||_ K auto-keep
>                             |||||__ C event count
>                             ||||___ R error rate
>                             |||____ S speed/performance
>                             ||_____ O updated online
>                             |______ P prefailure warning
> 
> [...]

The data up to this point informs us that you have 1 bad sector
on a 3TB drive, that is actually an expected event given the data
error rate on this stuff is such that your gona have these now
and again.

Given you have 1 single event I would not suspect that this drive
is dying, but it would be prudent to prepare for that possibility.


> 
> The ZFS pool is RAIDZ1, comprised of 3 WD Green 3TB HDD and one WD RED 3 TB HDD. The
> failure occured is on one of the WD Green 3 TB HDD.
Ok, so the data is redundantly protected.  This helps a lot.

> The pool is marked as "resilvered" - I do scrubbing on a regular basis and the
> "resilvering" message has now aapeared the second time in row. Searching the net
> recommend on SMART attribute 197 errors, in my case it is one, and in combination with
> the problems occured that I should replace the disk.

It is probably putting the RAIDZ in that state as the scrub is finding a block
it can not read.

> 
> Well, here comes the problem. The box is comprised from "electronical waste" made by
> ASRock - it is a Socket 1150/IvyBridge board, which has its last Firmware/BIOS update got
> in 2013 and since then UEFI booting FreeBSD from a HDD isn't possible (just to indicate
> that I'm aware of having issues with crap, but that is some other issue right now). The
> board's SATA connectors are all populated.
> 
> So: Due to the lack of adequate backup space I can only selectively backup portions, most
> of the space is occupied by scientific modelling data, which I had worked on. So backup
> exists! In one way or the other. My concern is how to replace the faulty HDD! Most
> HowTo's indicate a replacement disk being prepared and then "replaced" via ZFS's replace
> command. This isn't applicable here.
> 
> Question: is it possible to simply pull the faulty disk (implies I know exactly which one
> to pull!) and then prepare and add the replacement HDD and let the system do its job
> resilvering the pool?

That may work, but I think I have a simpler solution.

> 
> Next question is: I'm about to replace the 3 TB HDD with a more recent and modern 4 TB
> HDD (WD RED 4TB). I'm aware of the fact that I can only use 3 TB as the other disks are 3
> TB, but I'd like to know whether FreeBSD's ZFS is capable of handling it? 

Someone else?

> 
> This is the first time I have issues with ZFS and a faulty drive, so if some of my
> questions sound naive, please forgive me.

One thing to try is to see if we can get the drive to fix itself, first order
of business is can you take this server out of service?  If so I would
simply try to do a
repeat 100 dd if=/dev/whicheverhdisbad of=/dev/null conv=noerror, sync iseek=3262804632

That is trying to read that block 100 times, if it successful even 1 time
smart should remap the block and you are all done.

If that fails we can try to zero the block, there is a risk here, but raidz should just
handle this as a data corruption of a block.  This could possibly lead to data loss,
so USE AT YOUR OWN RISK ASSESMENT.
dd if=/dev/zero of=/dev/whateverdrivehasissues bs=512 count=1 oseek=3262804632

That should forceable overwrite the bad block with 0's, the smart firmware
well see this in the pending list, write the data, read it back, if successful
remove it from the pending list, if failed reallocate the block and write
the 0's to the reallocation and add 1 to the remapped block count.

You might google for "how to fix a pending reallocation"

> Thanks in advance,
> Oliver
> -- 
> O. Hartmann

-- 
Rod Grimes                                                 rgrimes_at_freebsd.org
Received on Tue Dec 12 2017 - 17:52:28 UTC

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