Overwriting or erasing a file
Methods that IBM Storage Archive Library Edition uses to modify data as if it were overwritten or erased.
IBM Storage Archive LE does not overwrite
data that is recorded on a tape medium, even if a file in the tape medium appears to be overwritten.
Instead, it appends new data to the end of existing data in a data partition. Then, it modifies the
index data so that the file entry included in the index points to the new data. The old data remains
on the tape medium, but is no longer indexed by IBM Storage Archive LE.
Note: Older
generations of the XML schema still reference the original data. Use the leadm tape
rollback command, or the leadm tape rollbacklist command to roll back
to older generations to get access to that data.
Similarly, IBM Storage Archive LE does not erase data from the tape
medium, even if a file in the tape medium appears to be erased. Instead, it removes only the file
entry from the index. Therefore, even if the user removes the file entry from the index, the
remaining capacity on the tape medium does not increase. Because data cannot be erased, the capacity
of a used tape can be increased only by reformatting the tape medium. Reformatting is done by using
the leadm tape format command with the -f option.
Attention: Although a medium can be reformatted by using the leadm
tape format command with the -f option, most data is not overwritten.
IBM Storage Archive LE does not have the tools
to provide a secure erasure. Refer to the Related information section to learn about the
multiple functional capabilities of the IBM® Tape Diagnostic
Tool in simplifying the task of maintaining IBM Storage Archive LE.