2.3 Replication and lost Hardlinks

David Carter dpc22 at cam.ac.uk
Fri Mar 31 03:29:11 EST 2006

On Fri, 31 Mar 2006, Roland Pope wrote:

> It would appear from my testing of the new 2.3 Replication code, that 
> you lose any 'SingleInstanceStore' benefits on the replica as hardlinks 
> on the master cannot be reproduced on the replica.

This is what message UUIDs are for. I've been replicating my single 
instance message stores quite happily for about 3 years now.

I don't use Cyrus 2.3. but here is the relevant section from the
install-replication document that Ken wrote:

Universally Unique Identifiers (UUIDs)

   An optional, but recommended step is to enable UUIDs for messages. Use
   of UUIDs improves efficiency by eliminating the synchronization of
   messages which the "replica" has already received from the "master".
   Note that UUIDs can be safely enabled and disabled at any time.

    1. Define the sync_machineid option in imapd.conf. This option
       specifies the numeric identifier (1 - 255) of the "master" machine
       which is used in constructing the UUID for each message on the
       server. This identifier MUST be unique across all active "backend"
       servers in a Murder. Example:

       sync_machineid: 1

    2. For each IMAP, NNTP and LMTP service in cyrus.conf, enable the
       provide_uuid argument. Example:

       imap    cmd="imapd" listen="imap" prefork=5 provide_uuid=1

David Carter                             Email: David.Carter at ucs.cam.ac.uk
University Computing Service,            Phone: (01223) 334502
New Museums Site, Pembroke Street,       Fax:   (01223) 334679
Cambridge UK. CB2 3QH.

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