UFS Snapshot lock time

[Kevin Day]

Is there any documentation out there that explains how to optimize UFS  
snapshotting?

Specifically, we've got a rather big filesystem that I'd like to do  
hourly snapshots of. I don't mind how long the snapshot itself takes,  
but the amount of time the filesystem is locked is a problem. We're  
"dead" for about 12 minutes per snapshotting.

Is there anything to tweak to speed it up any? (memory v.s. time  
exchange somewhere?) Is the length of time it takes a function of the  
number of inodes, directories, or...?


Relevant info:

Filesystem         1K-blocks     Used     Avail Capacity iused     
ifree %iused  Mounted on
/dev/da0s1a        739339824 73453348 606739292    11% 1717543  
93856471    2%   /

which is a 6 drive RAID-0 array.

CPU: Dual-Core AMD Opteron(tm) Processor 2218 (2593.52-MHz K8-class CPU)
usable memory = 17166548992 (16371 MB)
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs

In theory, this should be a rather fast box, but it is a rather large  
filesystem.

-- Kevin