On Fri, Feb 09, 2018 at 10:07:57PM +0000, Wol's lists wrote:
> On 09/02/18 21:22, Marc MERLIN wrote:
> >Interesting. I figured once a sector went pending once, it would not
> >actually be re-used and
> >be remapped on the next write. Seems like it didn't happen here.
>
> Because there's all sorts of reasons a sector can go pending.
>
> My favourite example is to compare it to DRAM. DRAM needs refreshing
> every couple of seconds, otherwise it loses its contents and cannot be
> read, but it's perfectly okay to rewrite and re-use it.
You're correct. The density of drives is so high now that writing a block
affects the ones around it.
> Likewise, the magnetism in a drive can decay such that the data is
> unreadable, but there's nothing actually wrong with the drive. (If the
> data next door is repeatedly rewritten, the rewrite can "leak" and trash
> nearby data ...) The decay time for that should be years.
Right. That's why I'm unhappy that it happened within a week of unpacking
the drives and 2 out of 5 had problems already.
> The problem of course is when the problem has a decay time measured in
> minutes or hours. The rewrite succeeds, so the sector doesn't get
> remapped, but when you next read it it has died :-(
Speaking of this, I still haven't gotten the drive to actually remap
anything yet.
On that 2nd drive, I'm seeing 7 pending sectors, and can't trigger any error
or remapping on them:
196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 7
# 1 Short offline Completed: read failure 90% 519 569442000
# 2 Short offline Completed: read failure 90% 519 569442000
# 3 Extended offline Completed: read failure 90% 518 569442000
# 4 Short offline Completed without error 00% 508 -
# 5 Short offline Completed without error 00% 484 -
# 6 Short offline Completed without error 00% 460 -
# 7 Short offline Completed without error 00% 436 -
# 8 Short offline Completed: read failure 90% 413 569441985
# 9 Extended offline Completed: read failure 90% 409 569441990
#10 Extended offline Completed: read failure 90% 409 569441985
#11 Extended offline Completed: read failure 90% 409 569441991
#12 Extended offline Completed: read failure 90% 409 569441985
So, running badblocks over that range should help, right?
But no, I get nothing:
myth:~# badblocks -fsvn -b512 /dev/sdf 569942000 569001000
/dev/sdf is apparently in use by the system; badblocks forced anyway.
Checking for bad blocks in non-destructive read-write mode
>From block 569001000 to 569942000
Checking for bad blocks (non-destructive read-write test)
Testing with random pattern: done
Pass completed, 0 bad blocks found. (0/0/0 errors)
In some way, unless I'm reading the wrong blocks, that would mean the blocks are good again?
But smart still shows
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 7
and a short offline test immediately shows
# 1 Short offline Completed: read failure 90% 519 569442000
Clearly, I still have some things to learn.
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/
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