Date: Tue, 21 Mar 2000 22:45:58 +0100 From: Wilko Bulte <wilko@yedi.iaf.nl> To: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> Cc: wilko@freebsd.org, Matthew Dillon <dillon@apollo.backplane.com>, Poul-Henning Kamp <phk@critter.freebsd.dk>, Alfred Perlstein <bright@wintelcom.net>, current@freebsd.org Subject: Re: patches for test / review Message-ID: <20000321224558.B3899@yedi.iaf.nl> In-Reply-To: <200003212114.NAA49370@gndrsh.dnsmgr.net>; from freebsd@gndrsh.dnsmgr.net on Tue, Mar 21, 2000 at 01:14:45PM -0800 References: <20000321200438.F966@yedi.iaf.nl> <200003212114.NAA49370@gndrsh.dnsmgr.net>
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On Tue, Mar 21, 2000 at 01:14:45PM -0800, Rodney W. Grimes wrote: > > On Tue, Mar 21, 2000 at 09:29:56AM -0800, Matthew Dillon wrote: > > > :> > > > :> I would think that track-caches and intelligent drives would gain > > > :> much if not more of what clustering was designed to do gain. > > > : > > > :Hm. But I'd think that even with modern drives a smaller number of bigger > > > :I/Os is preferable over lots of very small I/Os. Or have I missed the point? > > > > > As long as you do not blow away the drive's cache with your big I/O's, > > > and as long as you actually use all the returned data, it's definitely > > > more efficient to issue larger I/O's. > > > > Prefetching data that is never used is obviously a waste. 256K might be a > > bit big, I was thinking of something like 64-128Kb > > > > Drive caches tend to be 0.5-1Mbyte (on SCSI disks) for modern drives. > > Your a bit behind the times with that set of numbers for modern SCSI > drives. It is now 1 to 16 Mbyte of cache, with 2 and 4Mbyte being the > most common. Your drives are more modern than mine ;-) What drive has 16 Mb? Curious here.. -- Wilko Bulte Arnhem, The Netherlands http://www.tcja.nl The FreeBSD Project: http://www.freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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