> Did some quick tests of raw vs. ufs ... both under SDS 4.2.1 on Solaris8
> ... but it is turning out that ufs is faster. Does this seem reasonable ?
It does. When using the raw device, any I/O is done synchronously. When
using UFS, only metadata is written synchronously. For your "dd" example,
the latter is surely more performant.
The usual application of raw devices (or the "forcedirectio" flag) however
is DBMSes, which do their own caching and perform any disk I/O with the
O_SYNC flag. In that case raw devices win, because ...