On Tue, 12 Sep 2006, Wesley Craig wrote:
On a related note, what was the problem with accepting the Cambridge
patches for delayed folder deletion? I'm interested in working on
getting that or similar code accepted. Now that we have delayed expunge
for messages, we continue to run tape backups only for the case where
users inadvertently delete folders.
Replication and delayed expunge were added by Ken (working as a
contractor) back before he joined CMU. Replication was sponsored by
Columbia. Delayed expunge was sponsored by Fastmail, but mostly as a
performance enhancement. Unexpunge was just a nice side effect.
I believe that Ken implemented the delayed expunge from scratch. My
original "two expunge expunge" code is rather more involved:
1) Users can access expunged mail and deleted mailboxes using magic
mailbox hierarchies (.EXPUNGED/ and .DELETED/).
2) It hooks into the quota system to record the amount of expunged
space in each quota root. Messages are automatically expired when
global or per quota root limits are reached.
With hindsight (1) was a daft idea on my part. Our users struggle with the
idea of multiple mailboxes in their account, let alone magic mailbox
hierarchies. (2) is arguably useful if you don't have infinite storage on
your IMAP backends. There are however lots of other spool partitions which
can fill up under a determined denial of service attack.
Without (1) or (2), delayed mailbox deletion is really nothing more
exciting than a RENAME operation to some part of the mailbox hierarchy
without a quota root that only the system administrator can access.
--
David Carter Email: David.Carter@xxxxxxxxxxxxx
University Computing Service, Phone: (01223) 334502
New Museums Site, Pembroke Street, Fax: (01223) 334679
Cambridge UK. CB2 3QH.
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