Date: Mon, 18 Sep 2000 21:10:02 +0200 From: Neil Blakey-Milner <nbm@mithrandr.moria.org> To: Marc Tardif <intmktg@CAM.ORG> Cc: "Daniel C. Sobral" <dcs@newsguy.com>, freebsd-hackers@FreeBSD.ORG, freebsd-fs@FreeBSD.ORG Subject: Re: device naming convention Message-ID: <20000918211002.A77486@mithrandr.moria.org> In-Reply-To: <Pine.LNX.4.10.10009181358450.1921-100000@Gloria.CAM.ORG>; from intmktg@CAM.ORG on Mon, Sep 18, 2000 at 02:42:28PM -0400 References: <39C63ACD.441658CC@newsguy.com> <Pine.LNX.4.10.10009181358450.1921-100000@Gloria.CAM.ORG>
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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 nbm@mithrandr.moria.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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