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From: Nick Naym on 24 Jul 2010 21:51
In article C8709060.A24FE%noreply(a)nospam.invalid, MartinC at
noreply(a)nospam.invalid wrote on 7/24/10 6:43 AM:

> David Empson wrote:
>
>> You could try using the erase with zero data option in Disk Utility, but
>> it might fail if it encounters a bad sector.
>
> To my best of knowledge, quite the opposite - if a bad sector gets detected
> while *writing* the block, the drive firmware will re-allocate it.
>
> Sadly, the firmware will not do that while reading, so if a single block
> dies, every attempt to read it will just throw errors, only if you try to
> write data to it will re-allocate it.


You guys are losing -- nah: have already lost! -- me!

But your "re-allocate" comment sounded familiar: As I indicated in my
initial post about this problem,


� ...I decided to reformat/reinitialize the drive. However, my repeated
attempts to do so fail: After about 10 seconds of churning after I click the
�partition� button, DU gives up and issues the error message: �Partition
failed with the error: Could not unmount disk.�

Since the drive has a USB interface as well as FW, I also tried
reformatting/reinitializing via a USB port. That too was unsuccessful, but
the error message was different: �Partition failed with the error: POSIX
reports: The operation couldn�t be completed. Cannot allocate memory.� �


So, apparently re-allocation was an issue via USB.


(Any effort on your part to explain what the hell is going on without losing
me would be greatly appreciated.)



>
> Performing a "low level" format writing zeroes should dispose of all damaged
> blocks. There are two possibilities:
>
> 1) If the drive is mechanically fine, but only some small spots on the
> surface damaged, then the drive will be fine afterwards. A single damaged
> block does not automatically mean that the whole drive is dying.
>
> 2) If the drive is mechanically defective and actually *caused* the block
> damage, then zero-ing the whole drive will probably rip it in pieces.
>
> One way or the the other, you should know afterwards.
>

--
iMac (27", 3.06 GHz Intel Core 2 Duo, 4 GB RAM, 1 TB HDD) � OS X (10.6.3)

From: Nick Naym on 25 Jul 2010 17:28
In article C871BCCB.A2521%noreply(a)nospam.invalid, MartinC at
noreply(a)nospam.invalid wrote on 7/25/10 4:04 AM:

> Nick Naym wrote:
>
>> You guys are losing -- nah: have already lost! -- me!
>>
>> But your "re-allocate" comment sounded familiar: As I indicated in my
>> initial post about this problem,
>>
>>
>> � ...I decided to reformat/reinitialize the drive. However, my repeated
>> attempts to do so fail: After about 10 seconds of churning after I click the
>> �partition� button, DU gives up and issues the error message: �Partition
>> failed with the error: Could not unmount disk.�
>>
>> Since the drive has a USB interface as well as FW, I also tried
>> reformatting/reinitializing via a USB port. That too was unsuccessful, but
>> the error message was different: �Partition failed with the error: POSIX
>> reports: The operation couldn�t be completed. Cannot allocate memory.� �
>>
>>
>> So, apparently re-allocation was an issue via USB.
>>
>>
>> (Any effort on your part to explain what the hell is going on without losing
>> me would be greatly appreciated.)
>
> Sorry for the confusion... I try to explain (describing it a bit simpler as
> it actually is... ;-)
>
> The harddisk has zillions of blocks that are actually terribly sensitive -
> there is a real chance that some few might blow one day, even if the drive
> remains OK otherwise. In order to deal with that problem, the drive "itself"
> (i.e. the firmware) has a strategy...
>
> It keeps a lot of hidden blocks that are not used at all - you will not see
> them and you can't access them.
>
> Every time when you either read or write a block, the drive itself will know
> if it physically worked. Now the magic trick: If the drive *writes* a block
> and it physically fails because that single block got damaged since last
> time, it will silently swap the block with with one of those hidden
> "replacement" blocks - so the bad one will be marked out and never used
> again and the new one will be the substitute. This is called
> "re-allocation".

This much I knew. (But you did a great job exlpaining it!)



> You, as the user, will probably never even realize that this just happens -
> you wrote a file, it was written, fine!
>
> However, the drive will NOT do this when you *read* a block and the reading
> fails. Why? Because if it can't read the block, there is no way to get a
> replacement block with the same content.
>
> So if you have an ordinary file where one of the blocks got damaged, if you
> try to open it with an application or copy it in the Finder you get a box
> "Sorry this file can't be opened/copied because of an I/O error" or similar.
>
> (Note: What can you do then? You can't directly force the drive to swap that
> block because it will only do that while writing. The easiest way would be
> to simply delete the damaged file and either be sorry or copy it back from a
> backup. This will leave the bad block as "available" again. One day later,
> something tries to write on that block, sooner or later. At this time it
> gets replaced.)
>
> Now to your recent problem:
>
> Someone suggested that you may have a bad block "close to the boot blocks"
> of your directory structure.
>
> If you simply format your drive, it will *not* wipe the entire disk, all
> that it really does is to write out a new "empty directory". If the bad
> block would have been there, it would get substituted and the drive works
> again. However, let's assume that the bad block is within the reserved
> directory area but none of the blocks that get written for the "empty
> directory".
>
> Then DU would rattle for some 30 seconds writing the fresh directory and
> then follow up with some diagnostics if the drive appears valid. During that
> process it would read/scan the entire directory area, stumple upon the bad
> block while *reading*, get an error, and abort the whole process.
>
> Bingo! That would explain your report.

This sounds like what I've been experiencing.


> Now you try to format the drive in a different way using Windows. This
> different way uses different reserved areas, will not access the bad block
> and works. Bingo!
>
> Then you try to format it back on the Mac, it will access the original first
> area again,

It returns to that same area?? Why? It's no longer a "Mac" volume.

> stumble across the bad block again and fail again. Bingo!
>
> As you see, that was a pretty good idea and it sounded very reasonable.
>
> BUT - in the meantime you did this: You formatted the drive "low level",
> meaning that the utility wrote zeros on *every* block on the entire drive
> before doing anything else. If there would have been this single bad block
> at the beginning, it would have been re-allocated at this stage and the
> whole drive would be entirely OK afterwards.
>
> Sadly your problems came back afterwards - so although the idea with that
> block was very promising at the beginning, you have just disproved it - and
> this means that the drive is probably dying.
>
> If still under warranty, I would re-zero it one more time and ask LaCie to
> get a new one.
>

Well, it seem that I can re-zero the drive, and reformat/reinitialize it.
But then it only stays that way for a short while. What seems to happen is
that it goes through the same "failure" process all over again, then refuses
to allow me to re-zero or rewinitialize/reformat. The only times it seems to
allow me to do anything again is after I shut down the Mac, power down the
drive, and leave it alone for a long time. It may just be a coincidence, but
it's been only after long periods of powered-down "rest" that it then seems
to "recover" enough to allow me to erase it and/or reformat/reinitialize it.

Right now, it refuses to allow me to do anything. _Assuming_ it "recovers"
enough to allow me to do _anything_, should I attempt to
reformat/reinitialize, or simply go to DU's Erase tab, select one of the
"Security Options..." (is the "Zero Out" sufficient?), and hit the
"Erase..." button?




--
iMac (27", 3.06 GHz Intel Core 2 Duo, 4 GB RAM, 1 TB HDD) � OS X (10.6.3)

From: Nick Naym on 26 Jul 2010 08:44
In article C8731427.A258F%noreply(a)nospam.invalid, MartinC at
noreply(a)nospam.invalid wrote on 7/26/10 4:29 AM:

> Nick Naym wrote:
>
>>> Then you try to format it back on the Mac, it will access the original first
>>> area again,
>>
>> It returns to that same area?? Why? It's no longer a "Mac" volume.
>
> But you turn it into one (again). I got the impression that the drive works
> fine as long as it is "Windows"-formatted and only throws errors once it is
> formatted back to Mac. (Maybe I misunderstood this)
>
>> Well, it seem that I can re-zero the drive, and reformat/reinitialize it.
>> But then it only stays that way for a short while.
>
> Then it is definitely damaged. If it would have been only a single bad block
> on a very unlucky spot it would have been replaced at your zero-run.
>
> If the drive behaves good for a short time afterwards but starts trouble
> again, then it could be two/three possibilities:
>
> 1) The number of hidden blocks is (of course) limited. Once they are all
> replaced the drive can't do it any longer and will start to throw errors
> instantly even while writing. This means that a very large area is damaged
> and that means the drive is dead.
>
> 2) It's not a bad block on the surface at all but something that the drive
> itself damages while running. Either way, the drive is dead.
>
> 3) Of course it could be the interface/controller/internal wires. Then: dead
> once again.
>
>> The only times it seems to allow me to do anything again is after I shut down
>> the Mac, power down the drive, and leave it alone for a long time. It may
>> just
>> be a coincidence, but it's been only after long periods of powered-down
>> "rest"
>> that it then seems to "recover" enough to allow me to erase it and/or
>> reformat/reinitialize it.
>
> This is possible, it means that the drive starts to fail once its
> temperature rises. As stated above, you have already disproved the "one bad
> block" theory by your zero-run that didn't solve it.
>
>> Right now, it refuses to allow me to do anything. _Assuming_ it "recovers"
>> enough to allow me to do _anything_, should I attempt to
>> reformat/reinitialize, or simply go to DU's Erase tab, select one of the
>> "Security Options..." (is the "Zero Out" sufficient?), and hit the
>> "Erase..." button?
>
> You're still under warranty, right? Then get it exchanged. Write them a note
> that you formatted it writing zeros and that it still fails. That's
> sufficient, there's nothing more you can/should/have to try in order to file
> a complaint.
>
> If you feel worried about your data then *zero* it once more before sending
> it back.
>
>> (is the "Zero Out" sufficient?)
>
> This question may likely trigger a very heated debate... but to cut a long
> story short: Yes, a one-pass zero-run is sufficient.
>

The drive just mounted after being shut down all night. It mounted as a
fully formatted drive (i.e., it now appears just the way it did after the
last time I reinitialized it).

I can "zero out" the _drive_ two ways: via DU's Erase tab, or via DU's
Partition tab; and I can "zero out" the _volume_ one way: via DU's Erase
tab.

I don't know which of these 3 ways is preferred because I don't know what
the differences are.

....
....
>
> If you *don't* have warranty any more, please tell me - then you could try
> something more.
>

It's still under warranty...but I'm curious what "something more" you have
in mind.


--
iMac (27", 3.06 GHz Intel Core 2 Duo, 4 GB RAM, 1 TB HDD) � OS X (10.6.3)

From: David Empson on 26 Jul 2010 10:27
Nick Naym <nicknaym@_remove_this_gmail.com.invalid> wrote:

> I can "zero out" the _drive_ two ways: via DU's Erase tab, or via DU's
> Partition tab; and I can "zero out" the _volume_ one way: via DU's Erase
> tab.
>
> I don't know which of these 3 ways is preferred because I don't know what
> the differences are.

Quite simple:

If you use "zero out data", then Erase Drive or Partition Drive will
overwrite everything that was previously on the drive. Every sector of
the drive is overwritten with zeros.

In comparison, Erase Volume will only overwrite the content area of one
partition on the drive. The partition map, other partitions, and any
sectors outside of partitions such as free space are NOT overwritten, so
there is a possibility they might contain residual data.


As far as Erase and Partition of the Drive are concerned:

"Erase" of the drive is identical to using the Partition tab, selecting
a volume scheme of "1 partition", and NOT clicking the Options button
(i.e. keep the same partition map scheme).

The Partition tab gives you more options, particularly setting up
multiple partitions, changing the size of the partitions, and changing
the partition map scheme.

Using the Partition tab with "Current" selected as the Volume Scheme is
a more complex beast. Under Leopard and later, this can be used to
adjust existing partitions. Partitions can be added and deleted without
affecting the content of other partitions, and some resizing of
partitions is possible.

--
David Empson
dempson(a)actrix.gen.nz
From: David Empson on 26 Jul 2010 10:27
MartinC <noreply(a)nospam.invalid> wrote:

> Nick Naym wrote:
>
> > The drive just mounted after being shut down all night. It mounted as a
> > fully formatted drive (i.e., it now appears just the way it did after the
> > last time I reinitialized it).
> >
> > I can "zero out" the _drive_ two ways: via DU's Erase tab, or via DU's
> > Partition tab; and I can "zero out" the _volume_ one way: via DU's Erase
> > tab.
> >
> > I don't know which of these 3 ways is preferred because I don't know what
> > the differences are.
>
> The one that takes hours... (are you sure that you really did it that way?)
>
> Click on the "Erase" tab, then you will see a button called "security
> options" below (may be slightly different, I'm non-english here :-)
>
> You should get a dialog with 4 options:
> - don't delete data
> - write zeroes
> - write zeroes, 7 passes
> - write zeroes, 35 passes

Minor point: the 7 and 35 pass options don't write zeros 7 or 35 times:
they write random or specific data patterns 6 or 34 times respectively,
followed by a write zero pass. This is more effective at masking the
residual magnetic signal of previously written data.

(I agree with Martin's comments on zeroing data below.)

> The second one (write zeroes, 1 pass) is the one to go. Depending on the
> size of the drive, it will take some serious time. If you haven't done this
> (i.e. if the dialog has a "don't delete" setting and your successful format
> was pretty quick) then you may still have a possible bad block that may have
> caused all this.
>
> All formatting that is finished within some 1-2 minutes is nothing but
> writing a small "empty" directory and leave everything else as it is. If you
> do this, a new owner of your drive (or the company you send it to) could
> easily recover most of your personal data.
>
> > It's still under warranty...but I'm curious what "something more" you have
> > in mind.
>
> LaCie will not "repair" it, at least not for an acceptable price, so without
> warranty you can throw it away... before you do that you could open the case
> (this will *kill* your warranty, so don't do it for fun) and get out the
> plain drive. If you connect it to an internal S-ATA bus then you can read
> out the SMART data. This is like a black-box in an aeroplane, it will tell
> you exactly what happened during the errors.
>
> If it says OK then you know that the case/interface was broken and you have
> a spare internal disk for future use. If the drive was broken, you will know
> for sure.
>
> Sadly there is *no* way to retrieve SMART through either USB or FW.

I've heard of at least one USB to SATA bridge chipset which can retrieve
SMART data, but I don't have the details handy. It is relatively rare. I
haven't heard of any Firewire to SATA bridge chipsets which can do this.

No use if the enclosure in question doesn't have the right chipset.

--
David Empson
dempson(a)actrix.gen.nz
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