Gents.
I really appreciate your answers, but looks like we have different undertsanding how DAG works. (please, note, I said 'different'). But there is should be the only one correct. :)
I am reading right now docs regarding how DAG works and among other things:
I.
"
Specify the following information when creating a mailbox database copy:
...
The amount of time (in minutes) for log replay delay. This is the replay lag time, which sets how long to wait before the logs are committed to the database copy. You can turn off log replay delay by setting the value for it to 0.
"
II.
"
Continuous Replication–Block Mode
Exchange Server 2010 SP1 included continuous replication–block mode, and you could implement it to reduce your exposure to data loss on failover. This is achieved by replicating Extensible Storage Engine (ESE) log buffer writes to the passive database copies in parallel to writing them locally. Block mode automatically becomes active when continuous replication file mode is up to date with the database copies. The continuous replication block mode process is as follows:
"
From my point of view: every message (journal report\normal one) causes creating log which will be commited to mailbox database. There is no exclusion from this process. So, these logs are being replicated to all Exchange servers within DAG. Logs are commited to each copy of database, and commited to lag copy with some preconfigured delay. This commitment process will occur regardless of time how long this message was sitting in journal mailbox - 5 minutes of 1 hour. In another words I can't understand how journal reports (which has stayed in journal mailbox longer then 5 minutes) may (or may not) cause something related to Exchange lag copy?
I'll be happy to hear your opinions.
We use lag copy on journal mailbox databases because we apply the same approach to journal dbs as for normal mailbox db, but it should be reconsidered. I personally think that it makes no sense to create lag copy for journaling database, but I use completely different justification.
Thansk.