Identify files using specific logical block addresses.

Windows server backup is failing with a warning that "1536 bytes have not been backed up as they could not be read". At the same time there are errors in the even log regarding read errors on 4 logical block addresses in a RAID 5 array. Is there any way to find out which files these blocks are used in?
Thanks
Alan Mason
solplusAsked:
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DavidPresidentCommented:
Well, if you got your checkbook out than I could write a program, but it is a difficult task, if not impossible at this point.

Your filesystem hasn't been in read-only mode since this happened, so it is entirely possible that those 4 blocks that were part of file "X" are no longer associated with that file today.  

But if we assume for sake of argument that these blocks were part of a file that hasn't moved, then the code would run a program that traverses the file system and reads every block of every file and it monitors for read errors.  

There is no reverse-lookup (blocks to file) for NTFS, so it will have to be a custom bit of code.  If you booted linux and let it mount the physical drive in read-only mode, then it could be done with:

find / -type f  -exec cp {} /dev/null \;

This copies every file into the bitbucket and when you see a read-error, you have an unreadable file.  It may not be the same block number, but once you know the file name you can then use a utility like sys internals to monitor the block numbers used by a program. So then copy the file from windows and you'll know for sure.
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David Johnson, CD, MVPOwnerCommented:
a chkdsk will do the same if you use /r .. You should have many disk events in your system event log.. Actually you should have a failed drive somewhere in your raid-5 array.  Which raid-5 controller are you using? Windows software Raid? the motherboard $2 fake-raid chip? or a real raid controller?  You are using server quality drives and not drives rated for consumer useage i.e. green drives.. you should be using WD RE  / Seagate constellation drives
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DavidPresidentCommented:
Chkdsk /r doesn't give you file names.
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solplusAuthor Commented:
I know the logical block numbers of the blocks which give read errors. Does this make it easier to identify the files using them?
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DavidPresidentCommented:
Nope.  Somebody would have to write a program to cross reference blocks to files.  There is no native windows utility that does that.
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DavidPresidentCommented:
But ... you have a 99.999% chance of getting the right files by using a binary editor on the HDD.   Go to the block numbers immediately before and after the bad blocks and examine the raw contents.

Then you can tell the O/S to search for files that have those strings in them.   It might take a day or so to run (and I hope the blocks before and after have recognizable unique patterns, and not all zeros or ones) ... but this will work.
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