Can't write to flashdrive?


M

mm

A friend may have removed her USB flash drive without the proper
procedure, just pulled it out.

A) If you haven't written to the flash drive for, say, 10 minutes, and
you know all your writes concluded 10 minutes ago, do you really have
to use that procedure? I can't remember, and her know-it-all son says
No.

B) She can read from the drive but not write to it.

What's the next step? Running chkdsk?

C) She has to keep her client records for years to come. Should she
also burn CD's to hold them. Should she print them out?


Interestingly, she bought a second USB flash drive and it wouldnt'
work either. It didn't display the slightest message when she plugged
it in. The guy at Office Depot where she bought it said her OS was
old (she has XP SP2, but she didnt' remember that.) and he said it
couldn't find the drivers! Turns out the drive was too fat to go into
one USB slot, but it worked fine in the other!


She's retiring in two weeks and she has to take all her personal and
client files off the Board of Education laptop, so she'll have a copy.
And she has to remove them all so whoever sees the computer next won't
see them. The files are records of her psychological sessions with
public school students.
 
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P

Paul

mm said:
A friend may have removed her USB flash drive without the proper
procedure, just pulled it out.

A) If you haven't written to the flash drive for, say, 10 minutes, and
you know all your writes concluded 10 minutes ago, do you really have
to use that procedure? I can't remember, and her know-it-all son says
No.

B) She can read from the drive but not write to it.

What's the next step? Running chkdsk?

C) She has to keep her client records for years to come. Should she
also burn CD's to hold them. Should she print them out?


Interestingly, she bought a second USB flash drive and it wouldnt'
work either. It didn't display the slightest message when she plugged
it in. The guy at Office Depot where she bought it said her OS was
old (she has XP SP2, but she didnt' remember that.) and he said it
couldn't find the drivers! Turns out the drive was too fat to go into
one USB slot, but it worked fine in the other!


She's retiring in two weeks and she has to take all her personal and
client files off the Board of Education laptop, so she'll have a copy.
And she has to remove them all so whoever sees the computer next won't
see them. The files are records of her psychological sessions with
public school students.

Chkdsk is going to need to be able to write to the device, and
if the device (controller chip) is denying all write operations, you
aren't going to be able to repair it that way.

You could copy the data, sector by sector, onto a spare empty hard drive, and then
run chkdsk. The hard drive would be writable, so the corrections would "stick".
I would sooner try that, than try chkdsk on the flash right away.

If the file system is then intact on the hard drive, your next step is to
"blow away" the flash. Use your favorite eraser. Mine would be
something like this:

dd if=/dev/zero of=\\?\Device\Harddisk2\Partition0

and if the flash was the second storage device, it would be wiped starting
at sector zero. (dd --list will list all the partition names.) If the operation
is failing, then you know the flash is damaged. The "dd" program works at
the sector level, and nothing should be stopping it from working, save a
flash controller chip that refuses to do writes any more.

http://www.chrysocome.net/dd

Note that the program on that web page, has permission issues. For example,
you won't be able to do that erase thing to the C: you're booted from. It'll
return an error. Only certain partitions will be writable. Now, if I use
a Linux LiveCD, I can blast any partition on the Windows storage device I want,
but then there is the nuisance of having to boot into Linux.

Maybe there is some simpler test of the ability to write to the flash,
but that's the first thing I can find here to test with.

*******

The best you can do for archival, is use multiple media types and hope
for the best. A Flash drive can be erased by ionizing radiation. The
flash chip manufacturer, might rate them at 10 to 20 years storage. A
Hard drive doesn't come with any guarantees either - for example, the
surface plating might be attacked by moisture if stored improperly.
A hard drive is not hermetically sealed, but has a breather hole in
it to equalize atmospheric pressure. The pressure changes every day,
which means the drive "breathes in and out" constantly. The hepafilter
under the breather hole, stops dust, but corrosive gases might get
through.

You can look for archival grade optical media, but who knows how long
this will actually last. These are apparently available in packs of 5
or in packs of 50. You'd want an independent study, with accelerated
life testing, to verify the lifetime claims.

http://www.verbatim.com/prod/optica...cd-r-archival-grade-gold/ultralife-sku-96319/

You could try "storage in the cloud", encrypt the files with a decent
algorithm then upload them, but that would probably violate some
privacy protection rules. And would require some research about
what is considered the best method.

Printing on paper, using a bar code, would make the printed contents
readable later. You'd want to use "acid free" paper, for a long life.
Then the question is, what pigment to print with. I suppose laser
toner isn't too bad, but I'll bet even that would fade out with time.
By printing with bar codes, you might get better noise immunity (at
the price of reduced storage capacity). I think I'd rather take
my chances on the Verbatim discs :)

It is a fascinating subject, and something a retiring person can
spend days and days researching :)

Paul
 
Z

Zaphod Beeblebrox

mm said:
A friend may have removed her USB flash drive without the proper
procedure, just pulled it out.

A) If you haven't written to the flash drive for, say, 10 minutes,
and
you know all your writes concluded 10 minutes ago, do you really
have
to use that procedure? I can't remember, and her know-it-all son
says
No.


Know-it-all son is correct. I still do it, mostly out of habit I
suppose. That, and I don't like the warnings Windows puts up if you
don't.
B) She can read from the drive but not write to it.

That is a classic flash memory failure mode - the memory cells that
make up the drive have a certain number of write/erase cycles before
they no longer respond to the erase command. So if the file
allocation table is what fails, what you can end up with is a
read-only device like hers (and since the file allocation table is a
particularly frequently modified part of the drive, for cheap drives
without a good "wear leveling" scheme to keep from wearing out a cell
or group of cells before the rest, it is a particlularly common
section to have fail that way).
What's the next step? Running chkdsk?

It probably couldn't make things any worse, but I doubt it will help.

C) She has to keep her client records for years to come. Should
she
also burn CD's to hold them. Should she print them out?


If these records are that important she should be using multiple
backups, and multiple media types sure wouldn't be a bad idea. Not
sure I'd print them, personally.
Interestingly, she bought a second USB flash drive and it wouldnt'
work either. It didn't display the slightest message when she
plugged
it in. The guy at Office Depot where she bought it said her OS was
old (she has XP SP2, but she didnt' remember that.) and he said it
couldn't find the drivers! Turns out the drive was too fat to go
into
one USB slot, but it worked fine in the other!


She's retiring in two weeks and she has to take all her personal and
client files off the Board of Education laptop, so she'll have a
copy.
And she has to remove them all so whoever sees the computer next
won't
see them. The files are records of her psychological sessions with
public school students.

That being the case, I'd suggest that after she removes those records
she should use a "shredder" type application that overwrites free /
deleted space on the drive to make it harder for someone to recover
that highly sensitive data.

--
Zaphod

Arthur: All my life I've had this strange feeling that there's
something big and sinister going on in the world.
Slartibartfast: No, that's perfectly normal paranoia. Everyone in the
universe gets that.
 
M

mm

Know-it-all son is correct. I still do it, mostly out of habit I
suppose. That, and I don't like the warnings Windows puts up if you
don't.

But you wait until you're sure it's stopped writing? If you pull it
out in the middle of writing the FAT, it will be screwed up.

I once had a portion of the directory structure screwed up, but it was
just copies of other stuff, so I went one level higher and deleted
what was below.
That is a classic flash memory failure mode - the memory cells that
make up the drive have a certain number of write/erase cycles before
they no longer respond to the erase command. So if the file
allocation table is what fails, what you can end up with is a
read-only device like hers (and since the file allocation table is a
particularly frequently modified part of the drive, for cheap drives
without a good "wear leveling" scheme to keep from wearing out a cell
or group of cells before the rest, it is a particlularly common
section to have fail that way).


It probably couldn't make things any worse, but I doubt it will help.

Okay. If she would let me borrow the drive, I'd do it, but
If these records are that important she should be using multiple
backups, and multiple media types sure wouldn't be a bad idea. Not
sure I'd print them, personally.
Okay.


That being the case, I'd suggest that after she removes those records
she should use a "shredder" type application that overwrites free /
deleted space on the drive to make it harder for someone to recover
that highly sensitive data.

More work for me. I think she's overly worried. (She thinks if I
glimpse the file, she's failed to preserve security, even though I
don't know these kids and will never have contact with them and won't
remember much and forget all that within a couple hours. These kids
are not famous and they can't be blackmailed, and the school system
has 100,000 kids, and no one at the central office knows who any of
them are . But I'll keep this in mind for when it matters to me, not
just her. They must have given her instructions about what she
should do.

Thanks
 
M

mm

Chkdsk is going to need to be able to write to the device, and
if the device (controller chip) is denying all write operations, you
aren't going to be able to repair it that way.

Darn. :)
You could copy the data, sector by sector, onto a spare empty hard drive, and then
run chkdsk. The hard drive would be writable, so the corrections would "stick".
I would sooner try that, than try chkdsk on the flash right away.

Okay. Not your problem but for background: Frankly I don't want to do
this at her house. Every time I go over there, it takes hours, and I
don't have all that I need, and she probably won't let me take the
flash drive with me. She thinks I'm goign to read the files. I don't
know these kids -- Yes, I know the rules don't make exceptions for
people who don't know them, but still. And I will forget everything I
see in less than a day anyhow. But it's a matter of honor to her.

And if I tell her I"m copying the data to my harddrive, even
temporarily, she'll have a fit, and I'm honor-bound to tell her, I
think. Darn. She hasn't got time to lend me her computer and probably
wouldn't let me take it to my house for fear I'd read something!!

I'm very interested for myself in all you have below, but for her,
maybe we'll end up leaving it read-only, since she already bought
another flashdrive, and it wouldn't hurt her to buy a third, since
retirement is a one-time expense, and it's the cost of having a
responsible job.
If the file system is then intact on the hard drive, your next step is to
"blow away" the flash. Use your favorite eraser. Mine would be
something like this:

dd if=/dev/zero of=\\?\Device\Harddisk2\Partition0

and if the flash was the second storage device, it would be wiped starting
at sector zero. (dd --list will list all the partition names.) If the operation
is failing, then you know the flash is damaged. The "dd" program works at
the sector level, and nothing should be stopping it from working, save a
flash controller chip that refuses to do writes any more.

http://www.chrysocome.net/dd

Very interesting. I saved it.
Note that the program on that web page, has permission issues. For example,
you won't be able to do that erase thing to the C: you're booted from. It'll
return an error. Only certain partitions will be writable. Now, if I use
a Linux LiveCD, I can blast any partition on the Windows storage device I want,
but then there is the nuisance of having to boot into Linux.

Maybe there is some simpler test of the ability to write to the flash,
but that's the first thing I can find here to test with.

It's good enough. Thanks.
*******

The best you can do for archival, is use multiple media types and hope
for the best. A Flash drive can be erased by ionizing radiation. The
flash chip manufacturer, might rate them at 10 to 20 years storage. A
Hard drive doesn't come with any guarantees either - for example, the
surface plating might be attacked by moisture if stored improperly.
A hard drive is not hermetically sealed, but has a breather hole in
it to equalize atmospheric pressure. The pressure changes every day,
which means the drive "breathes in and out" constantly. The hepafilter
under the breather hole, stops dust, but corrosive gases might get
through.
Yikes.

You can look for archival grade optical media, but who knows how long
this will actually last. These are apparently available in packs of 5
or in packs of 50. You'd want an independent study, with accelerated
life testing, to verify the lifetime claims.

http://www.verbatim.com/prod/optica...cd-r-archival-grade-gold/ultralife-sku-96319/

You could try "storage in the cloud", encrypt the files with a decent
algorithm then upload them, but that would probably violate some
privacy protection rules.

Absolutely. She'll never go for that. But for other circumstances,
I'll kee it in mind.
And would require some research about
what is considered the best method.

Printing on paper, using a bar code, would make the printed contents

A bar code?? So it's scannable without using OCR? But can't be read
from the paper directly??
readable later. You'd want to use "acid free" paper, for a long life.
Then the question is, what pigment to print with. I suppose laser
toner isn't too bad, but I'll bet even that would fade out with time.
By printing with bar codes, you might get better noise immunity (at
the price of reduced storage capacity). I think I'd rather take
my chances on the Verbatim discs :)

It is a fascinating subject, and something a retiring person can
spend days and days researching :)

LOL.

She wants to learn to paint, and to speak Chinese!

Thanks a lot.
 
W

William R. Walsh

Hi!
A) If you haven't written to the flash drive for, say, 10 minutes, and
you know all your writes concluded 10 minutes ago, do you really have
to use that procedure?

It's a very good idea if you have changed the option to allow Windows
to perform write-caching against the device in question. By default,
Windows does not enable write-caching against removable storage
devices.

You may not have written anything to the drive, but:

A) you don't know if the operating system or an application has/is/
will be writing something to the drive.
B) Windows does not police its "dirty" (write-cached data that has yet
to be written) data store all that closely. It's possible for
something to be slinging around in there for quite a while in some
cases.

William
 
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M

mm

Hi!


It's a very good idea if you have changed the option to allow Windows
to perform write-caching against the device in question. By default,
Windows does not enable write-caching against removable storage
devices.

You may not have written anything to the drive, but:

A) you don't know if the operating system or an application has/is/
will be writing something to the drive.
B) Windows does not police its "dirty" (write-cached data that has yet
to be written) data store all that closely. It's possible for
something to be slinging around in there for quite a while in some
cases.

William

Thanks. I'll bear this in mind and continue to use the proper
procedure to close a drive.

(I lost track of this newsgroup for a while and just got back. )
 

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