Re: force remapping a pending sector in sw raid5 array

[Marc MERLIN <marc@merlins.org>]

On Wed, Feb 07, 2018 at 10:42:39AM +0100, Kay Diederichs wrote:
> I've adjusted the last-block and first-block numbers in the command
> above so that they
> a) encompass the known bad blocks
> b) start and end on 4k-boundaries
> 
> This command leaves those blocks intact that still can be read.
> 
> After that, use a destructive-write badblocks e.g.
> 
> badblocks -sfvwb512 /dev/sdh <x> <y>
> You'll have to adjust x and y to match just those blocks that cannot be
> read, based on the output of the first badblocks run.

I will try this next, thanks (still, for learning purposes).

But, I'm confused by what happened. The md check ran to completion.
It found things and supposedly fixed them:
[240351.053406] md/raid:md7: read error corrected (8 sectors at 9159374528 on sdf1)

Strangely, it did nothing with this:
[287271.959779] sd 4:4:0:0: [sdh] tag#6 Add. Sense: Unrecovered read error - auto reallocate failed

The full resync/check is here:
[89601.694910] md: data-check of RAID array md7
[240342.514062] ata5.02: exception Emask 0x0 SAct 0x7fffffff SErr 0x0 action 0x0
[240342.514073] ata5.02: failed command: READ FPDMA QUEUED
[240342.514081] ata5.02: cmd 60/60:30:70:fc:f0/02:00:21:02:00/40 tag 6 ncq dma 311296 in
[240342.514086] ata5.02: status: { DRDY ERR }
[240342.514089] ata5.02: error: { UNC }
[240342.515351] ata5.02: configured for UDMA/133
[240342.515470] ata5.02: exception Emask 0x1 SAct 0x0 SErr 0x0 action 0x0 t4
[240342.515578] sd 4:2:0:0: [sdf] tag#6 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[240342.515585] sd 4:2:0:0: [sdf] tag#6 Sense Key : Medium Error [current] 
[240342.515590] sd 4:2:0:0: [sdf] tag#6 Add. Sense: Unrecovered read error - auto reallocate failed
[240342.515596] sd 4:2:0:0: [sdf] tag#6 CDB: Read(16) 88 00 00 00 00 02 21 f0 fc 70 00 00 02 60 00 00
[240342.515600] print_req_error: I/O error, dev sdf, sector 9159375984
[240342.515726] ata5: EH complete
[240350.486141] ata5.02: exception Emask 0x0 SAct 0x30 SErr 0x0 action 0x0
[240350.486153] ata5.02: failed command: READ FPDMA QUEUED
[240350.486160] ata5.02: cmd 60/08:20:c0:fe:f0/00:00:21:02:00/40 tag 4 ncq dma 4096 in
[240350.486166] ata5.02: status: { DRDY ERR }
[240350.486169] ata5.02: error: { UNC }
[240350.487403] ata5.02: configured for UDMA/133
[240350.487450] sd 4:2:0:0: [sdf] tag#4 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[240350.487454] sd 4:2:0:0: [sdf] tag#4 Sense Key : Medium Error [current] 
[240350.487458] sd 4:2:0:0: [sdf] tag#4 Add. Sense: Unrecovered read error - auto reallocate failed
[240350.487462] sd 4:2:0:0: [sdf] tag#4 CDB: Read(16) 88 00 00 00 00 02 21 f0 fe c0 00 00 00 08 00 00
[240350.487466] print_req_error: I/O error, dev sdf, sector 9159376576
[240350.487493] ata5: EH complete
[240351.053406] md/raid:md7: read error corrected (8 sectors at 9159374528 on sdf1)
[287271.958430] ata5.04: exception Emask 0x0 SAct 0xffc0 SErr 0x0 action 0x0
[287271.958442] ata5.04: failed command: READ FPDMA QUEUED
[287271.958449] ata5.04: cmd 60/40:30:f0:d7:64/05:00:86:02:00/40 tag 6 ncq dma 688128 in
[287271.958454] ata5.04: status: { DRDY ERR }
[287271.958457] ata5.04: error: { UNC }
[287271.959691] ata5.04: configured for UDMA/133
[287271.959770] sd 4:4:0:0: [sdh] tag#6 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[287271.959775] sd 4:4:0:0: [sdh] tag#6 Sense Key : Medium Error [current] 
[287271.959779] sd 4:4:0:0: [sdh] tag#6 Add. Sense: Unrecovered read error - auto reallocate failed
[287271.959783] sd 4:4:0:0: [sdh] tag#6 CDB: Read(16) 88 00 00 00 00 02 86 64 d7 f0 00 00 05 40 00 00
[287271.959785] print_req_error: I/O error, dev sdh, sector 10844690416
[287271.959889] ata5: EH complete
[315132.651910] md: md7: data-check done.

Now, the sync is comnplete, and my bad blocks are still there?
myth:~# smartctl -A /dev/sdh
196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       2

myth:~# smartctl -A /dev/sdf
196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       7

The pending sectors should have been re-written and become Reallocated_Event_Count, no?

Reading 
myth:~# hdparm --read-sector 287409520 /dev/sdh
still gives me what looks like non garbage data (but it could be) and
[315411.087451] ata5.04: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
[315411.087462] ata5.04: failed command: READ SECTOR(S) EXT
[315411.087469] ata5.04: cmd 24/00:01:70:4f:bc/00:00:4c:00:00/e0 tag 0 pio 512 in
[315411.087469]          res 51/40:01:70:4f:bc/00:00:4c:00:00/e0 Emask 0x9 (media error)
[315411.087474] ata5.04: status: { DRDY ERR }
[315411.087478] ata5.04: error: { UNC }
[315411.108028] ata5.04: configured for UDMA/133
[315411.108075] ata5: EH complete

So, mdadm is happy allegedly, but my drives still have the same bad sectors they had
(more or less).

Yes, I know I should trash (return) those drives, but I still want to
understand why I can't get basic block remapping working
Any idea what went wrong?

Thanks,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/                       | PGP 7F55D5F27AAF9D08