Unix Cache / Buffer

Does anyone know how the unix buffer / cache is set in a Solaris based system ?
( I presume it is a kernel based setting )

I notice from SAR -d that my read cache is consistently at 100% but my write cache frequently falls below 65%. What does this mean. Should I be tuning the write cache and if so, how ?

Is there a single buffer / cache or separate ones for read & write ?

Uber article describing Solaris caching.

http://www.solarisinternals.com/si/reading/sunworldonline/swol-07-1999/swol-07-filesystem3.html