USB Flash Drive Integrity Checker

  • Thread starter Thread starter jaugustine
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J

jaugustine

Hi,

I am a heavy user of USB flash drives. I recently had a minor issue
with a couple of files I copied to a hard drive. They were not exactly the
same as they were on the flash drive. A file compare exposed a change.
I copied them again from the flash drive and the second time they matched.

This is the first time this happened. This particular 2G flash drive I
use the most. After I copy all files from it, I plan to "Format" it.

Does anyone know of an integrity checker for USB flash drives?

Thank You in advance, John
 
J. P. Gilliver (John) said:
That is even more irritating than people who just say "google it".
Click to expand...

Especially since the redirection site requires scripting be enabled.
Google does not.
 
Does anybody have a recommendation for an integerity checker?
Googleing does not tell me if others I might trust have used it
successfully.
 
J. P. Gilliver (John) said:
In message <[email protected]>, Guess Who


That is even more irritating than people who just say "google it".
Click to expand...

Sometimes, USB flash drives give non-reproducible errors.

As a result, if you told me you integrity checked a USB key,
I'd have to discount the effectiveness of such a test. It
doesn't guarantee that the next time you use it, it won't
have a problem.

And if the integrity checker does a lot of writes, all it's
doing is wearing out the flash blocks. A modern MLC flash
is rated for as low as 3K cycles. And that limits the cost
effectiveness of a write/read verify type of test. If you left
it running over night, it might wear out the flash.

It's easy to cook up your own test case. First, acquire a checksum
tool, such as md5sum, sha1sum, fciv etc. Checksum a large file
on your hard drive. Copy the file to the flash. Run the checksum
tool again, this time reading from the flash. The file size chosen,
should be so large, that the file can't fit in system memory,
in the system file cache. So if I had a 4GB RAM computer, 3.1GB free,
I'd use any file larger than 3.1GB for a test. If the USB key has a LED,
verify the LED is active during the read-verify step. (If the file
was read from the file cache in system memory, then you wouldn't see
much if any accesses to the USB key.)

If you want large, random files, you can use dd. You would first
send the file to your hard drive. And then checksum it, before
copying the file to the USB key.

http://www.chrysocome.net/dd

dd if=/dev/random of=J:\testfile.bin bs=65536 count=65536

That would create a 4GB file as J:\testfile.bin and the data
content would be (pseudo-)random. If J: happened to be FAT32,
you'd change the parameters to 65536, 65535 to stay under the
4GB limit.

When someone writes a dedicated test program, they likely
have the option of turning off the system file cache, rather
than defeating it in the crude way I'm suggesting.

The Microsoft "fsutil" utility, can also create large files.
If the target file system is FAT32, in fact fsutil is fine
for that function. If you use "fsutil" and do a createfile on
an NTFS partition, the file is "sparse" and very little writing
is done to the file system. And then you're stuck with the
conundrum, of whether making copies of the newly created file,
preserves the sparseness or not. So while "fsutil" is a valid
option in some cases, I just don't bother with it any more.
I would have preferred that Microsoft wasn't nearly so clever,
as to do it that way. (On a Sun system, the mkfile utility
always creates real files, and was my old favorite when on
SunOS/Solaris systems. The "dd" util is what I use now.)

http://en.wikipedia.org/wiki/Sparse_file

Paul
 
J. P. Gilliver (John) said:
That is even more irritating than people who just say "google it".
Click to expand...

J.P.,

Actually, what is irritating to some, myself included, is an individual that
makes NO attempt whatsoever to research answers or find solutions by
themselves. They expect other people to hand them solutions with no effort
on their part. So, I actually applaud those who respond with "google it."
With so much information available in microseconds via the internet, it is a
sad commentary on his part. If he felt the answers he obtained were
unreliable or did not solve his problem, then, of course, inquire via a
newsgroup, forum or blog.

Take my reply as an example of negative reinforcement. The next time he
asks a question, he'll remember the irritating response he received

Cheers,
GW
 
Guess said:
J.P.,

Actually, what is irritating to some, myself included, is an individual that
makes NO attempt whatsoever to research answers or find solutions by
themselves.
Click to expand...

Alas, not everyone that has expended the effort to do prior research
makes note of all of it when asking for help in Usenet. They may come
here after they already failed to find satisfactory search results on
their own. A post that remarks on everything researched or tried before
posting here could become a tome that no one would read or avoid as soon
as they opened it. However, lack of such information means that
respondents will likely duplicate the OP's same efforts, if any (beyond
the OP posting here).
They expect other people to hand them solutions with no effort
on their part. So, I actually applaud those who respond with "google it."
Click to expand...

Without providing reasonable search criteria (as you did), someone
responding with merely "Google it" is a waste of bandwidth and disk
space. Without reasonable search criteria that narrows the results to
something actually usable to the OP, such a respondent might as well say
"gribble frockle mendersmittenburg" or some other babble trash.
With so much information available in microseconds via the internet,
it is a sad commentary on his part. If he felt the answers he
obtained were unreliable or did not solve his problem, then, of
course, inquire via a newsgroup, forum or blog.
Click to expand...

Maybe that's what he did. You might assume by omission that the OP
didn't do any prior research but it is an assumption.
Take my reply as an example of negative reinforcement. The next time he
asks a question, he'll remember the irritating response he received
Click to expand...

Wishful thinking on your part. You are also assuming that he will have
scripting enabled in his web browser. Yet you probably know there is a
large number of Firefox users that have the NoScript extension installed
or Google Chrome users with NotScript extension installed (or even IE
users that know how to use .reg files to disable/enable scripting). A
user visiting that site won't see anything happen there and figure you
were stupid in providing a non-working non-solution. Turn off scripting
in your web browser or use an add-on/extension that disables it by
default when visiting non-whitelisted sites and see just what that
irritation site looks like. You won't see much happen there.

I doubt you using that site will have the lasting effect you wish it had
versus just giving them the Google search URL. If they're too lazy to
do the research before asking, you really think using an irritating
"Google tutorial" site is going to make them rethink their future
knee-jerk posts?

While you provided a better response than just "Google it" by including
some search criteria, I'm pretty sure any user visiting that site would
either not take into account that you are trying to negatively reinforce
that they should do their own prior research or they'll just figure you
for an ahole and not bother with your search at the irritation site.
The effect might not be what you thought it would be.

Don't bother trying to teach them with your unmentioned objectives.
Just give them a Google search URL with reasonable criteria that gives
them results that are usable to them. If they aren't going to "learn"
to do their own research beforehand by giving them a good search URL,
pushing them to irritation site isn't going to "learn" them, either.
 
VanguardLH said:
Alas, not everyone that has expended the effort to do prior research
makes note of all of it when asking for help in Usenet. They may come
here after they already failed to find satisfactory search results on
their own. A post that remarks on everything researched or tried before
posting here could become a tome that no one would read or avoid as soon
as they opened it. However, lack of such information means that
respondents will likely duplicate the OP's same efforts, if any (beyond
the OP posting here).


Without providing reasonable search criteria (as you did), someone
responding with merely "Google it" is a waste of bandwidth and disk
space. Without reasonable search criteria that narrows the results to
something actually usable to the OP, such a respondent might as well say
"gribble frockle mendersmittenburg" or some other babble trash.


Maybe that's what he did. You might assume by omission that the OP
didn't do any prior research but it is an assumption.


Wishful thinking on your part. You are also assuming that he will have
scripting enabled in his web browser. Yet you probably know there is a
large number of Firefox users that have the NoScript extension installed
or Google Chrome users with NotScript extension installed (or even IE
users that know how to use .reg files to disable/enable scripting). A
user visiting that site won't see anything happen there and figure you
were stupid in providing a non-working non-solution. Turn off scripting
in your web browser or use an add-on/extension that disables it by
default when visiting non-whitelisted sites and see just what that
irritation site looks like. You won't see much happen there.

I doubt you using that site will have the lasting effect you wish it had
versus just giving them the Google search URL. If they're too lazy to
do the research before asking, you really think using an irritating
"Google tutorial" site is going to make them rethink their future
knee-jerk posts?

While you provided a better response than just "Google it" by including
some search criteria, I'm pretty sure any user visiting that site would
either not take into account that you are trying to negatively reinforce
that they should do their own prior research or they'll just figure you
for an ahole and not bother with your search at the irritation site.
The effect might not be what you thought it would be.

Don't bother trying to teach them with your unmentioned objectives.
Just give them a Google search URL with reasonable criteria that gives
them results that are usable to them. If they aren't going to "learn"
to do their own research beforehand by giving them a good search URL,
pushing them to irritation site isn't going to "learn" them, either.
Click to expand...

Vanguard,

I don't disagree with you. I certainly don't expect a dissertation on
specific attempts they made to find a solution before posting here. When
you respond with a solution to a problem and the OP replies with "I tried
that", how do you feel? Do you feel like you wasted your time responding
when they could have mentioned what they tried ? I would. A simple "I
searched the internet but couldn't find a solution" would suffice. At least
it indicates they made an attempt. That's all.

Regardless, I am a realist. If these people haven't learned at this stage
in their lives (presuming they are adults) then they never will. Others
will forever be shoving solutions down their piehole and that's fine. Also,
I really don't care how they interpret my response. If scripting isn't
enabled then my solution helped them as much as their own attempts did.
Searching google for solutions isn't part of Einstein's General Theory of
Relativity !

GW
 
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