Tech Note 008
Title: A backup failed after a span. How can I find out which files are on the first volume and which are on the second?
Updated: May 2005
 
As FlashNet writes its index before it writes the data, it is possible that in the event of a backup failing during data write the index on disk may be an inaccurate representation of the actual data on the backup. For this reason, any backup or archive that fails should be re-executed to ensure all files and data are correctly written.

However, it is sometimes necessary for the user to find out which files have been written and which have not. In the event that the backup failed after a span it is necessary to use the FlashNet command line utilities dtool and display as detailed below (in this example the first volume is called A001, the second volume is A002, and the archive number that spanned is 12):

1. Determine the point at which the span occurred
From a command line type
    #    display A001
This outputs to the screen a list of all the archives on volume A001. The final archive, archive 12, is followed by an End Of Media Header. This is where the volume spanned. The End of Media Header has a record count, which is the point in the backup at which the span occurred. Make a note of this value.

2. Determine the position within the archive of each file
From a command line type
    #    dtool -NA001 -tvCA12
This instructs FlashNet to display on screen a list of all files within archive number 12 on volume A001. The list of files is displayed with a record count thus
   t /tmp/john/servers/README.servers 12202 bytes @ rec 5816
   t /tmp/john/servers/RELNOTES.TXT 2863 bytes @ rec 5817
The '@ rec xxxx' figure is the record count at which the files were (or would have been) written.

3. Compare the record count of the End of Media Header with the record count of the files
Any file whose record count is smaller than that of the End of Media Header was written before the span. Any file with a record count higher than that of the End of Media Header was written after the span.
 

 ==END==

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