migration and seen flag

[Bron Gondwana]

On Fri, Jan 06, 2012 at 10:17:26AM -0500, Ron Vachiyer wrote:
> however it doesn't create any .seen files like the 2.1.x version, it seems to store seen information in the "cyrus.index" file in each users mailspool directory.  I am using the invoca rpm build, is this a particularity or is there another setting I have to set/unset to imitate the previous behaviour?

Seen data is only stored in .seen files for shared or other user
mailboxes.  The seen data for the mailbox owner is stored in the
cyrus.index.  This has two benefits:

1) lower IO for the most common case.  We need to update the
   cyrus.index file anyway to record the new MODSEQ.
2) owner seen becomes shared seen if you switch to shared seen
   mode on the mailbox, so that you don't wind up with one huge
   file full of shared seen data if you have a lot of shared
   mailboxes.

Seen files were actually a lot of extra IO on 2.3, small files
with multiple fsyncs!

Bron.