From owner-freebsd-hackers Wed Feb 16 18:38:45 2000 Delivered-To: freebsd-hackers@freebsd.org Received: from builder.freebsd.org (builder.FreeBSD.ORG [204.216.27.24]) by hub.freebsd.org (Postfix) with ESMTP id E08C337B57B; Wed, 16 Feb 2000 18:38:43 -0800 (PST) (envelope-from dscheidt@enteract.com) Received: from mail.enteract.com (mail.enteract.com [207.229.143.33]) by builder.freebsd.org (Postfix) with ESMTP id 4F905132EF; Wed, 16 Feb 2000 18:38:03 -0800 (PST) Received: from shell-3.enteract.com (dscheidt@shell-3.enteract.com [207.229.143.42]) by mail.enteract.com (8.9.3/8.9.3) with SMTP id UAA79564; Wed, 16 Feb 2000 20:37:13 -0600 (CST) (envelope-from dscheidt@enteract.com) Date: Wed, 16 Feb 2000 20:37:13 -0600 (CST) From: David Scheidt Reply-To: David Scheidt To: Matthew Dillon Cc: Joe Greco , Mike Smith , hackers@FreeBSD.ORG Subject: Re: Filesystem size limit? In-Reply-To: <200002160022.QAA46284@apollo.backplane.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tue, 15 Feb 2000, Matthew Dillon wrote: > Not with LVD. The whole point was to be able to have longer SCSI > busses. > > LVD allows SCSI bus cable lengths up to 25 meters. With 16 devices > the limit is 12 meters. That's 36 feet, folks! Which isn't really that much, once you get to the lots of busses point. It gets hard to physically fit everything. While you can put 16 devices on a SCSI bus, you can't do that and get highest performance out of them. Depending on what the data access model is, I have found between four and eight devices is best. I helped build a database server with just under 200 disks. If we hadn't been using hardware that let us put I/O controllers 10 meters from the CPU cabinet, we would have had a hard time building the machines with all the busses under the length limit. This was a duplex machine, so that's an additional problem. Of course, today I'd do it with a lot fewer disks. David To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message