On Mon 2000-09-18 (14:42), Marc Tardif wrote:
> > > 4b. Should I then be using /dev/rwd0s2 or /dev/rwd0s2a
> > > for reading and writing (of course, this is assuming
> > > block i/o of multiples of 512 bytes)?
> >
> > Nope, using raw devices is almost always wrong, and we even got rid of
> > raw device in latter versions of FreeBSD. A "raw" device is an
> > _unbuffered_ device. It has nothing to do with formats or types.
> >
> Got rid of raw devices in later versions of FreeBSD? What if I purposely
> want unbuffered io? There are instances, such as with databases, where the
> buffer cache is useless.
>
> I understand that in many cases, databases using the raw device
> practically reinvent the wheel by programming what is effectively another
> filesystem (which, by the way, is most likely slower than bsd's ffs). Even
> Oracle, which used to be one of the "you gotta use a raw partition if you
> want any speed at all" type, has moved into the "use a normal partitoin or
> regular file unless you do things like sharing a RAID between two hosts"
> camp.
>
> Yet, there are still isolated cases where raw io can be beneficial. What
> should I do for raw io in later versions of FreeBSD?
We didn't get rid of raw devices. We got rid of block devices, and kept
character devices.
Neil
--
Neil Blakey-Milner
Sunesi Clinical Systems
[EMAIL PROTECTED]
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