suspend writes for external snapshot

[Robert]

Greetings,
I am trying to determine if there is a way to suspend write activity on 
a FreeBSD filesystem (currently 6.0R) in order to take a snapshot with 
external SAN software (Falconstor IPStor)?
Falconstor does not "support" FreeBSD but I am trying to make it work.
I am guessing that if the fs can be put into a state as in "During steps 
three through six, all write activity on the filesystem is suspended." 
(http://www.usenix.org/publications/library/proceedings/bsdcon02/mckusick/mckusick_html/index.html) 
then an external snapshot could be taken of the system using IPStor or 
any other SAN software?
Perhaps a tool that uses vn_start_write() and vn_write_finished() that a 
  sysadmin could use without mucking things up.

Am I reading too much into this, should I not worry about the filesystem 
state and simply allow background fsck to run when booting from any of 
the inconsistent snapshots?

TIA
Robert