deleting indices

[cheese at nosuchhost.net]

hi

i have dovecot 2.0.9 - the version from rhel6 - and the following setup:

two imap-servers with distinct /var/indices. those directory is local 
only, no sharing. the users mailboxes life on a shared nfs-storage.
the two servers are setup active/passive: only one server is active and in 
case of a problem or maintenance the second server jumps in. no director 
in place. we would like to upgrade to rhel7 and add a director. there 
would be dovecot 2.2.10, but will take some time.

one application (horde + activesync which use imap to access emails) seems 
to have troubles during the second server being active. horde relies according to their deveolpers 
heavily on modseq/qresync and if we switch to the seconds side there is 
another set of index-files.

my knowledge was that deletion/corruption of index-files would be never a 
problem, as dovecot recreates them automatically. is this true for QRESNC, 
too?

* is it a problem to have a old set of index-files on the second server, 
as this system is only in use every 3-4 weeks?

* would it be better to start with empty indices? but there we have 
trouble with horde. and as it seems only with horde. "normal" imap-clients 
seem to be fine.

yours
josef