Worth writing zeros to my used hard drives?

[Jax]

Home user with XP Pro.

I bought some 160 GB hard drives a couple of years ago and they got
filled up with data.

I have now migrated all the data off these 160 GB hard drives and will
now use the drives to hold backups.

QUESTION ---> As the HDDs are now empty is it worth writing zeros,
before using them again, in order to force the HDD to map out any
defective sectors?

QUESTION --> Or will mapping out of any defective sectors happen
automatically when any bad sectors are next written to, which means it
is not worth writing the zeros?

 

[Rod Speed]

Home user with XP Pro.

I bought some 160 GB hard drives a couple
of years ago and they got filled up with data.

I have now migrated all the data off these 160 GB
hard drives and will now use the drives to hold backups.

I wouldnt bother myself, I'd just get another 250-500G drive to hold backups.

QUESTION ---> As the HDDs are now empty is it worth writing zeros,
before using them again, in order to force the HDD to map out any
defective sectors?

Nope, it shouldnt have developed any and should be discarded if it has.

QUESTION --> Or will mapping out of any defective sectors
happen automatically when any bad sectors are next written to,
Yes.

which means it is not worth writing the zeros?

Correct.

 

[Folkert Rienstra]

Home user with XP Pro.

I bought some 160 GB hard drives a couple of years ago and they got
filled up with data.

I have now migrated all the data off these 160 GB hard drives and will
now use the drives to hold backups.

QUESTION ---> As the HDDs are now empty is it worth writing zeros,
before using them again, in order to force the HDD to map out any
defective sectors?

QUESTION --> Or will mapping out of any defective sectors happen
automatically when any bad sectors are next written to, which means it
is not worth writing the zeros?

Ah, a question that can only be asked if you know what the answer is.
Smart one.

 

[Paul Rubin]

QUESTION ---> As the HDDs are now empty is it worth writing zeros,
before using them again, in order to force the HDD to map out any
defective sectors?

I'd say write over the drive and use the SMART interface to detect
whether the HDD finds any bad sectors. If it does, replace the drive.

 

[DaveW]

You do not have to write out zero's on them.

 

[Folkert Rienstra]

I'd say write over the drive and use the SMART interface to detect
whether the HDD finds any bad sectors.

Nonsense, aren't you a regular here?
You don't need to do that to 'find' any. Bad sectors that are to be reassigned
by writes will already be known as candidate bad sectors and logged as such
under "Current Pending Sector Count". If there aren't any, none will be reas-
signed by writing. To detect any new you need to read the drive, not write it.

If it does, replace the drive.

Yup, who cares whether the cause is external.
You just keep replacing them until you get a clue.
Good for business, no.

 

[Paul Rubin]

Nonsense, aren't you a regular here?
You don't need to do that to 'find' any. Bad sectors that are to be reassigned
by writes will already be known as candidate bad sectors and logged as such
under "Current Pending Sector Count". If there aren't any, none will be reas-
signed by writing. To detect any new you need to read the drive, not write it.

These drives apparently hadn't been in use (or at least written to)
for a while. It is possible that bad sectors developed while the
drive was sitting on the shelf. I've certainly taken working drives
out of service, then had them fail when I tried using them a year or
two later.

 

[paulmd]

Home user with XP Pro.

I bought some 160 GB hard drives a couple of years ago and they got
filled up with data.

I have now migrated all the data off these 160 GB hard drives and will
now use the drives to hold backups.

QUESTION ---> As the HDDs are now empty is it worth writing zeros,
before using them again, in order to force the HDD to map out any
defective sectors?

QUESTION --> Or will mapping out of any defective sectors happen
automatically when any bad sectors are next written to, which means it
is not worth writing the zeros?

It's worth zeroing the data on the drives under two circumstances.

1) You're selling them, and don't want any one to steal your bank
account info, etc.

2) You don't want anyone to see your porn collection


If it has bad sectors, replace the unit. According to a very recent
google study of over 100,000 consumer grade hard drives, those with
read errors were 39 times more likely to fail within 60 days than
those without.

It's worth checking the drive for bad sectors.

 

[Folkert Rienstra]

It's worth zeroing the data on the drives under two circumstances.

1) You're selling them, and don't want any one to steal your bank
account info, etc.

2) You don't want anyone to see your porn collection


If it has bad sectors, replace the unit. According to a very recent
google study of over 100,000 consumer grade hard drives,

those with read errors were 39 times more likely to fail within
60 days than those without.

Which says absolutely nothing if those without don't fail, now is it.

And the exact phrase was:
"After the first scan error, drives are 39 times more like-
ly to fail within 60 days than drives without scan errors."

Unfortunately there is no such thing as a 'scan error'.

Your 'read' errors appear under probational counts.
"The critical threshold for probational counts is also one:
after the first event, drives are 16 times more likely to fail
within 60 days than drives with zero probational counts."

There were other inconsistencies in the report as well, like lower
risk numbers for the total lifetime (longer than 60 days).

They also didn't say what they considered a failure and whether the
'failed' drives actually failed in a different system once replaced.
Neither did they check whether it was the system killing the drives.

 

[Arno Wagner]

Home user with XP Pro.

I bought some 160 GB hard drives a couple of years ago and they got
filled up with data.

I have now migrated all the data off these 160 GB hard drives and will
now use the drives to hold backups.

QUESTION ---> As the HDDs are now empty is it worth writing zeros,
before using them again, in order to force the HDD to map out any
defective sectors?

Not really needed, since if you write new data, this will happen anyways.

QUESTION --> Or will mapping out of any defective sectors happen
automatically when any bad sectors are next written to, which means it
is not worth writing the zeros?

It will. But you may want to run a long SMART selftest to find weak
sectors before using the disks.

Arno

 

[Folkert Rienstra]

These drives apparently hadn't been in use (or at least written to)
for a while. It is possible that bad sectors developed while the drive
was sitting on the shelf. I've certainly taken working drives out of
service, then had them fail when I tried using them a year or two later.

You didn't understand a word of what is written above, don't you, Rubin.

Do I have to repeat it for you: *They won't show with only writing*.
*To detect any new you need to read the drive, not write it.*

 

[Folkert Rienstra]

Not really needed, since if you write new data, this will happen anyways.

It will.

No, it won't for new bad sectors that have not been detected before.

 

[Paul Rubin]

Do I have to repeat it for you: *They won't show with only writing*.

Yes, thanks, that helped.

 

[Arno Wagner]

Yes, thanks, that helped.

As usual, Folkert is wrong. They may or may not show up as "pending"
in the SMART attributes, but after writing they will show up as
reallocated defects in SMART. They will not before if the drive
failed to read them.

Arno

 

[Folkert Rienstra]

Crucial line reinserted:

As usual, Folkert is wrong.

And as usual you are so immensely stupid and eager to make a fool of yourself
that you don't even notice that you repeat at the end what I said, babblebot.

They may or may not show up as "pending" in the SMART attributes,
but after writing they will show up as reallocated defects in SMART.

Only the pending ones, your babblebotness. Only the ones you *already know of*.
And no, not all pending ones will be reassigned, as the drive will read check them
after writing and they may well prove to be good afterall, after that.

They will not before if the drive failed to read them.

And that is exactly what makes them pending, you babblebot moron.
Only then will they *show* as pending in the SMART attribute list.
Writes to possibly bad sectors that the drive is yet to know of will go without any
action and may still be bad after. On the other hand they may also be cured by it.
But the drive will still be unaware of them.

Which is what I said in the previous post and what got conveniently snipped.
As usual you haven't got a clue what was being discussed.

The question was: does he need to write to the drive to see new bads
(possible bads he obviously isn't yet aware of) and get rid of them.
Since he isn't aware of problems there are no current pending ones.
So the answer was: No, you need to read first to catch them as pending,

 

[paulmd]

Which says absolutely nothing if those without don't fail, now is it.

Of COURSE drives without bad sectors do fail. Otherwise the statement
would be different.

And the exact phrase was:
"After the first scan error, drives are 39 times more like-
ly to fail within 60 days than drives without scan errors."

Unfortunately there is no such thing as a 'scan error'.

I'd presumed it was a synonym for a bad spot on the drive in
question.

Your 'read' errors appear under probational counts.
"The critical threshold for probational counts is also one:
after the first event, drives are 16 times more likely to fail
within 60 days than drives with zero probational counts."

There were other inconsistencies in the report as well, like lower
risk numbers for the total lifetime (longer than 60 days).

They also didn't say what they considered a failure and whether the
'failed' drives actually failed in a different system once replaced.
Neither did they check whether it was the system killing the drives.

Actually, yes they did specify what they counted as a failure. I'm
paraphrasing because I don't have the report in front of me. "A drive
is considered to have failed if it was placed as part of a repair
operation".

 

[Folkert Rienstra]

Of COURSE drives without bad sectors do fail.

But not all. Without a percentage, 39 times or 16 times is a useless number.

Otherwise the statement would be different.

I'd presumed it was a synonym for a bad spot on the drive in question.

Yup, detected by a very particular action of the drive. Problem is,
there is no such attribute with that name. So how will they know.
They particularly isolated them from the pending ('probational')
counts, the online and the offline reallocated counts, so it's not those.

Actually, yes they did specify what they counted as a failure. I'm
paraphrasing because I don't have the report in front of me. "A drive is
considered to have failed if it was replaced as part of a repair operation".

But no explanation of what a 'repair operation' is and what prompts it.
A simple single bad block in the wrong place may prompt a 'repair operation'
where the drive is simply replaced as part of a quick fix by lack of other repair
options. That doesn't necessarily mean that the drive itself is beyond repair.

 

[paulmd]

But not all. Without a percentage, 39 times or 16 times is a useless number.

The percentages are on figure 6.

Yup, detected by a very particular action of the drive. Problem is,
there is no such attribute with that name. So how will they know.
They particularly isolated them from the pending ('probational')
counts, the online and the offline reallocated counts, so it's not those.

It's also not Seek error, or CRC error (listed separately).

It's most likely that they are referring to attribute 1. (Read Error
Rate)

http://en.wikipedia.org/wiki/Self-Monitoring,_Analysis,_and_Reporting_Technology



They're different.

Probational counts is attribute 195.

But no explanation of what a 'repair operation' is and what prompts it.
A simple single bad block in the wrong place may prompt a 'repair operation'
where the drive is simply replaced as part of a quick fix by lack of other repair
options. That doesn't necessarily mean that the drive itself is beyond repair.

A repair operation is a pretty broad subject.

Not many people bother to fix failed drives, except for the purposes
of data recovery. Though it's possible Google does. I would however
consider a drive that needed to be repaired to have failed.

By the underlying tone of the report, replaced drives were often
retested.

"From an end-user's perspective, a defective drive is
one that misbehaves in a serious or consistent enough
manner in the user's specific deployment scenario that
it is no longer suitable for service. Since failures are
sometimes the result of a combination of components
(i.e., a particular drive with a particular controller or cable,
etc), it is no surprise that a good number of drives
that fail for a given user could be still considered operational
in a different test harness. *** We have observed
that phenomenon ourselves, including situations where
a drive tester consistently "green lights" a unit that invariably
fails in the field.***"


You can also tell that today I DO have a copy of the report in front
of me.

 

[ed]

It's worth zeroing the data on the drives under two circumstances.

1) You're selling them, and don't want any one to steal your bank
account info, etc.

2) You don't want anyone to see your porn collection

If you give them a good enough porn collection, they'll forget about
your bank account.