archiving notes

[Eric Dean Tribble <tribble>]

I'm going to start putting out occasional messages on thoughts about
archiving.  These are things that came up in my meeting with MarkM.

Below are some actions that the archiving system could support.  The
list is by no means comprehensive or the correct cut on the actions
they describe.  This is an attempt to specify one dimension of the
proposal (it doesn't address whether tapes can be transferred between
machines, for instance).

Generate a copy (by a user for anything he can read).  - A user can
spin stuff to a tape.  I'm deliberately not addressing what 'stuff'
is.

Generate a believable copy.  - If the system sees this tape later, it
can authenticate the contents and restore the documents from it.

Generate a retrievable/believable copy.  - Retrievable means that the
computer knows how to get from the blank space of the document to the
archived tape.  This corresponds to the typical meaning of archived.
The tape must necessarily be believable to the backend.

mark purgeable - presumably done after the system knows about a R/T
tape.  Since the system can now restore the document, it could be
removed from disk if space gets tight.

restore believable copy.  Read it in and fill in the partiality
representing the document, recreate all the appropriate Berts and
Stamps, etc.

dean