[OpenAFS] hard link behavior

Jaap Winius jwinius@umrk.nl
Wed, 07 Jul 2010 18:13:50 +0200

Quoting "Chas Williams (CONTRACTOR)" <chas@cmf.nrl.navy.mil>:

> this would be fraught with peril to implement safely and isnt reversible.
> say someone changes their mind about this acl policy.  ...

You could write a conversion tool, but why bother? The circumstances =20
under which the setting I've suggested would be implemented are very =20
specific. In the unlikely event of a mistake, just copy the data to a =20
another/new volume.

> afs has a better scheme for this -- copy on write.  create a volume.
> dump in your backup.  now vos clone that volume.  this would be a
> snapshot of that backup.  future backups go into the original volume,
> vos clone'ing as necessary for the snapshots in time.

That's interesting for sure, but it sounds as though you're not =20
familiar with disk-based backups, because that's no substitute for =20
what I have in mind.

> this does have some limits.  vos clone is limited to 4 copies and you
> cannot move those volumes off the same partition as the original.

Well, there you go: it's even worse than I thought. With my disk-based =20
backup system, I can e.g. maintain 50 easily accessible backups of a =20
single home directory that hardly use more than 2-3 times the space of =20
the original. Wouldn't it be nice to have one of these to go with your =20
home directory instead of a single, standard .backup volume?

All I'm suggesting is that a specific switch be added so that one =20
limitation can be traded for another and new things can become possible.

> instead of creating a special hardlinks mode perhaps expending beyond
> the 7 slots for copy on write volumes would be more productive.

Certainly a good idea -- that's something that I've wondered about =20
before -- but I see no reason why both of our ideas should not be made =20