Question on the exact nature of the DBs

[Nick Fisher]

Hello all...
  In my quest to sort out the DB errors (see the 'What happened to my db/
?' thread) I've been having a bit of trouble figuring out exactally what
all the DBs are. I was hoping that someone who could look at what I've
got so far and give me a headsup on any errors and answer a few
(hopefully) quick questions.....

1) duplicates
Configured with: --with-duplicate-db=DB
Location: /var/imap/deliver.db
Description: Specifies which database backend to use for the duplicate
delivery database.

2) mboxlist
Configured with: --with-mboxlist-db=DB
Location: /var/imap/mailbox.db
Description: Specifies which database backend to use for the mailbox list.
(More here:
http://asg.web.cmu.edu/cyrus/download/imapd/overview.html#recoverymbox)

3) tls db
Configured with: --with-tls-db=DB
Location: /var/imap/tls_sessions.db
Description: Specifies which database backend to use for the TLS cache.

4) seen db
Configured with: --with-seen-db=DB
Location: /var/imap/user/u/user-name.seen
Description: Specifies which database backend to use for the seen state.

5) subscriptions db
Configured with: --with-subs-db=DB
Location: /var/imap/user/u/user-name.sub
Description: Specifies which database backend to use for the subscriptions
list.

Now there are two lots of data that do not appear to be covered in the
above list, db/ and the mailbox/cyrus.(header|index|cache|seen).

What is db/? I can't figure out what exactally it does or what you use to
configure it at compile time. I guess it's part of mailboxs.db in some way
but I would love a better answer....

The mailbox/cyrus.* files are fairly well explained here:
http://asg.web.cmu.edu/cyrus/download/imapd/overview.html#recoverymboxdir
But I can't figure out what there format is or how it's configured..... is
it native to cyrus?

Why is the reconstruct command in the doc
(http://asg.web.cmu.edu/cyrus/download/imapd/overview.html#recoverymbox)
marked as 'NOTE: CURRENTLY UNAVAILABLE'? What versions does that apply to?

And my final question is about the seen dbs. Each user has their own seen
db and a cyrus.seen in every mailbox. Are the cyrus.seen files just a
backup to reconstruct the /var/imap/user/u/user-name.seen?

Many thanks for the help already given and hopefully for the answers
coming ;)

  Nick