Re: Need help with "reallocated sector count"?

On Nov 14, 12:55 pm, Arno Wagner <m...@xxxxxxxxxxx> wrote:
Previously kimiraikkonen <kimiraikkone...@xxxxxxxxx> wrote:
Arno, Rod (no quatiton mark :-) ), Franc,
Thanks you for following this topic and keeping replying.
So, as overall when you looked at SMART values, i want to summarize
what i got in that topic?
1- There are 98 reallocated bad sectors but there's no unallocated as
a threat of data loss? Right?

The 98 sectors have been moved out of the way. Not risk from them.

So, they were containing data before they've got reallocated. Right?

2-ID Attribute Description Threshold Value Worst Data Status
05 Reallocated Sector Count 36 98 98 98 OK: Value is normal
That means there are 98 reallocated sectors, but still couldn't
completely understand for Seagate what "threshold - 36" means? It
shouldn't be percantage, does it mean that i'm allowed to allocate
100-36 = 64 bad ones? (frustrating)

You have bad sector number x. This inceases on more bad sectors
found. By some obscure procedure that gives value y. This decreses
with more bad secors found. A first hypothesist is that y decreses
by 2 for every 98 bad sectors. The asumption is that the
initial value was 100. Then you have threshold value z.
If y ever reaches or falls below z, then you get a bad SMART status
for the disk.

Very frustrating but good sample if it's straight forward true.
Manufacturer have to explain their raw value and Smart calculations
than guessing.

The current speculation is that in your particular case x and y
have the same numerical value, purely by accident.

3- The other SMART values are fine as stated by many programs. Right?

Looked that way.

4- A "reallocated sector count" shows the amount of reallocated /
replaced sectors silently while the drive is operating. When the drive
has a problem with sector, first it tries to replace that sectors with
a "spare" sector thus a "reallocated sector" statistic is updated.

The reallocation count will increase on any successful
realocation.


How much sector will my drive be allowed to reallocate? (eg: What
about for a modern 40gb drive ? )

Reallocation can happen later. If it was unsuccesful so far, you
get a "pending sector". As son as it has been reallocated,
the pending secor attribut is decreased again.

If the sector is completely unreadable or unreallocatable, you see it
as "bad" marked in surface scan tools like Seatools. Did i understand
correct?

Yes.

That's why the full / surface scan utilities are there. They report
"bad" , really "bad" sectors which can't be allocated by firmware of
HDD. Right?

5- Though a drive has "reallocated sectors", if it can read every data
(checking with several disk reading utilites), it doesn't have a
unallocatable / unfixable bad sectos which are the reasons of real
data loss.

The reallocated sectros are recognized _and_ corrected problems.
These sectors will not cause problems in the future. Other
sectors may go bad, but if a complete surface scan does not
show any, all data is in sectors that are fine or at least look
like it. In rare cases a sector can work with some data, but be
defect with other data. Very rare with today's disks, due to
heavy use of error correcting codes.

You still may want to do a complete surface scan regularly,
so that the disk can recognize sectors slowly going bad
in time and can rescue the data in them. I run such a test
every 14 days automatically, but once every 1-2 months should
do fine. You can make that a part of your standard backup
procedure.

I usually do it if i record important data. But still "none" bad
sectors have been reported by surface scan of Seatools.

So, can i say i don't have any bad sectors present at the moment?


Those 5 questions are the ones i see answered them clearly.
Again, thank you for following and helping. Very helpful...

You are welcome.

Arno

Thanks.

.

Relevant Pages

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