Internal - How does Netvault calculate free space on a tape? (4046826)

Title: How does Netvault calculate free space on a tape?
Date: Jul 07
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Description: This document discusses how Netvault:Backup calculates how much space remains on a tape prior to writing data to it.

When writing to a tape it is important that we do not attempt to write past the end of the tape itself as this would render the backup useless. In order to prevent this situation Netvault asks the drive how much free space there is remaining on the tape it is writing. This is called a Free Space Estimates (FSE). The actual commands used to interrogate the drive differ for each drive.

The value returned is used in conjunction with the tape reserve value to determine if there is enough space remaining to continue. If there is not then that tape has a filemark written and it is then considered full.

There are certain times when FSE are calculated:
1. When a tap