First, I've never used the rollinglogged persistence manager.
Part of the startup is to load the queue with the messages.
If there isn't enough memory the messages will be flushed
back out into the cache store on disk.
This is inefficient for the file based pms because you
endup with two copies of a persistent message on disk if memory
The jdbc2 version implements a combined pm/cache.
Another part of startup is to rollback incomplete transactions by
reading the transactions logs.
The RollOverSize is used to control how many messages
go in each transaction log before a new log is started.