Setting dbnosync: do I need to set a checkpoint?

[TechnoSophos <technosophos@gmail.com>]

Using an HDB backend, if I set the dbnosync parameter in slapd.conf,
how often will modifications be flushed to the underlying database?

I did not find the Berkeley DB documentation to be terribly helpful in
this case. It mentions that more frequent checkpointing can help:
(http://www.oracle.com/technology/documentation/berkeley-db/db/api_c/env_set_flags.html#DB_TXN_NOSYNC)

Should I be using the checkpoint parameter in slapd.conf? I was under
the impression (based on threads I have seen in other mailing lists)
that checkpoint didn't actually do anything anymore. (And I have not
had much luck with using txn_checkpoint in the DB_CONFIG file -- it
produces errors).

I'm not asking for troubleshooting help on fixing checkpointing. I
just want to know how risky it is to use dbnosync, and if
checkpointing can help minimize risks.

Matt