multiple dumps on an exabyte

[Phil Hammar]

In article <7334 at brazos.Rice.edu> bcsaic!paula at beaver.cs.washington.edu (Paul Allen) writes:
>
>If you just dd a file onto the front of the tape, the rest of the tape
>will no longer be accessible.
[...]
>Paul Allen
>pallen at atc.boeing.com

This is not true in our case.  We have an Exabyte and driver from Perfect
Byte, Inc., and we dd a file of nulls onto the front of the tape to
reserve space for a table of contents when the rest of the tape has
finished being written.  We then tar(1) the TOC onto teh front of the
tape.  There are two caveats: 1) the file of nulls must be big enough so
that the end of file marker from the tar does not overwrite the end of
file marker from the null file (we use 10 MB of nulls as suggested by
George Goble in his excellent article in Sun-Spots Vol. 7, Issue 68), and
2) both end of file markers have to be skipped to get to the contents of
the tape (ie. mt fsf 2)

			Hope this helps,
			Phil Hammar