Files corrupted on transfers?

[Mobius]

We have backed up files and folders routinely innumerable times over the
years for working systems to external drives - mostly USB. These back-ups
have come in might useful a few times!

Sometimes we find that some files on the external drive give a 'corrupt' or
'crc' or 'damaged' error when tried to be opened. This happens randomly and
for any file type - exe, doc, html, iso or other.

On a rough average we estimated that about a couple of percent of all such
back up files are thus unusable. While no critical files have been 'lost' so
far - we always have two separate back-ups of everything - it still is
interesting. Because no two identical file on both back-ups appear unusable
at the same time - at least so far.

Just wondering - what might be the possible cause/causes - and what might be
done to ensure better transfers. So far we use either a manual 'copy' in
Windows Explorer or sometimes a file-sync utility like SmartSync Pro.

Regards and thanks for any insights.

Mobius
--------

 

[Pegasus \(MVP\)]

We have backed up files and folders routinely innumerable times over the
years for working systems to external drives - mostly USB. These back-ups
have come in might useful a few times!

Sometimes we find that some files on the external drive give a 'corrupt'
or
'crc' or 'damaged' error when tried to be opened. This happens randomly
and
for any file type - exe, doc, html, iso or other.

On a rough average we estimated that about a couple of percent of all such
back up files are thus unusable. While no critical files have been 'lost'
so
far - we always have two separate back-ups of everything - it still is
interesting. Because no two identical file on both back-ups appear
unusable
at the same time - at least so far.

Just wondering - what might be the possible cause/causes - and what might
be
done to ensure better transfers. So far we use either a manual 'copy' in
Windows Explorer or sometimes a file-sync utility like SmartSync Pro.

Regards and thanks for any insights.

Mobius
--------

CRC (Cyclic Redundancy Check) errors are bad news. They occur when Windows
is unable to read data from the storage medium. They invariably point to a
hardware problem.

 

[smlunatick]

We have backed up files and folders routinely innumerable times over the
years for working systems to external drives - mostly USB. These back-ups
have come in might useful a few times!

Sometimes we find that some files on the external drive give a 'corrupt' or
'crc' or 'damaged' error when tried to be opened. This happens randomly and
for any file type - exe, doc, html, iso or other.

On a rough average we estimated that about a couple of percent of all such
back up files are thus unusable. While no critical files have been 'lost'so
far - we always have two separate back-ups of everything - it still is
interesting. Because no two identical file on both back-ups appear unusable
at the same time - at least so far.

Just wondering - what might be the possible cause/causes - and what mightbe
done to ensure better transfers. So far we use either a manual 'copy' in
Windows Explorer or sometimes a file-sync utility like SmartSync Pro.

Regards and thanks for any insights.

Mobius
--------

As Pegasus suggested, your error might be hardware related. You
should consider replacing the "affected" hard drive and get the older
drive checked out with the drive manufacturer's diagnostic tools.

 

[1PW]

We have backed up files and folders routinely innumerable times over the
years for working systems to external drives - mostly USB. These back-ups
have come in might useful a few times!

Sometimes we find that some files on the external drive give a 'corrupt' or
'crc' or 'damaged' error when tried to be opened. This happens randomly and
for any file type - exe, doc, html, iso or other.

On a rough average we estimated that about a couple of percent of all such
back up files are thus unusable. While no critical files have been 'lost' so
far - we always have two separate back-ups of everything - it still is
interesting. Because no two identical file on both back-ups appear unusable
at the same time - at least so far.

Just wondering - what might be the possible cause/causes - and what might be
done to ensure better transfers. So far we use either a manual 'copy' in
Windows Explorer or sometimes a file-sync utility like SmartSync Pro.

Regards and thanks for any insights.

Mobius
--------

Hello Mobius:

You have received fine advice from others in this thread. If anything
you back up is mission critical, you may wish to consider making
independent checksums or hashes.

I realize that your data files may not be static so to supplement your
outstanding two backup scheme, please consider:


Take a md5/sha1 checksum before the static file is transfered /and/
after. Immediately you will /independently/ know if the destination
file was written correctly. Reverse the above procedure? Sure!

Caveat: A file's hash can't be checked after it's been compressed. But
it can after it's been uncompressed.

Many checksum utilities are freeware:

<http://www.thefreecountry.com/utilities/free-md5-sum-tools.shtml>

Many web sites, with downloadable elements, will publish the file's hash
in a small separate ASCII text file.

Warm regards,

Pete

 

[Lil' Dave]

We have backed up files and folders routinely innumerable times over the
years for working systems to external drives - mostly USB. These back-ups
have come in might useful a few times!

Sometimes we find that some files on the external drive give a 'corrupt'
or
'crc' or 'damaged' error when tried to be opened. This happens randomly
and
for any file type - exe, doc, html, iso or other.

On a rough average we estimated that about a couple of percent of all such
back up files are thus unusable. While no critical files have been 'lost'
so
far - we always have two separate back-ups of everything - it still is
interesting. Because no two identical file on both back-ups appear
unusable
at the same time - at least so far.

Just wondering - what might be the possible cause/causes - and what might
be
done to ensure better transfers. So far we use either a manual 'copy' in
Windows Explorer or sometimes a file-sync utility like SmartSync Pro.

Regards and thanks for any insights.

Mobius

So far you've said making copies of files on 2 USB drives. Failures during
read or opening files, not writes. No file is common with problem on either
drive. Am curious as you did not note a commonality, or deny a commonality
between some of your PCs and not others and this problem.

 

[Randem]

Does your USB drive operate as a networked drive? If so this sometimes can
be a problem with writing files from a utility. Windows has know issues with
programs writting to networked drives.

--
Randem Systems
Your Installation Specialist
The Top Inno Setup Script Generator
http://www.randem.com/innoscript.html
How Banks STEAL Your Money
www.financialtrainingservices.org/bankreviews.htm

 

[Mobius]

Thanks for the helpful pointers. We are considering replacing the external
drives with newer hardware soon - hope that solves the problem!