From owner-freebsd-hackers Mon Aug 2 20:13:11 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from bilby.prth.tensor.pgs.com (bilby.prth.tensor.pgs.com [157.147.232.237]) by hub.freebsd.org (Postfix) with ESMTP id 832F2151F1 for ; Mon, 2 Aug 1999 20:13:02 -0700 (PDT) (envelope-from shocking@ariadne.prth.tensor.pgs.com) Received: from bandicoot.prth.tensor.pgs.com (bandicoot.prth.tensor.pgs.com [157.147.224.1]) by bilby.prth.tensor.pgs.com (8.9.3/8.8.8) with ESMTP id LAA23326 for ; Tue, 3 Aug 1999 11:10:20 +0800 (WST) Received: from ariadne.tensor.pgs.com (ariadne [157.147.227.36]) by bandicoot.prth.tensor.pgs.com (8.9.3/8.8.8) with SMTP id LAA19983; Tue, 3 Aug 1999 11:11:38 +0800 (WST) Received: from ariadne by ariadne.tensor.pgs.com (SMI-8.6/SMI-SVR4) id LAA16741; Tue, 3 Aug 1999 11:11:39 +0800 Message-Id: <199908030311.LAA16741@ariadne.tensor.pgs.com> X-Mailer: exmh version 2.0.2 2/24/98 To: hackers@freebsd.org Cc: shocking@bandicoot.prth.tensor.pgs.com Subject: Adding disks -the pain. Also vinum Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Tue, 03 Aug 1999 11:11:39 +0800 From: Stephen Hocking-Senior Programmer PGS Tensor Perth Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG The people who I work for were about to junk a bunch of 6 year old disks when I snaffled them. Among them were 4 DEC DSP5400S (3.8GB each), with a nice external case. These disks had been doing duty on a boat carrying out seismic surveys, attached to misc. Sun workstations. These are typical of their vintage - full height 5 1/4" drives fast narrow SCSI2, and noisy as all blazes. I have them hooked up to a NCR810, as one striped FS (it's just for experiments, not valuable data). fdisking them was easy, but disklabelling them was a royal pain. I ended up editing the /etc/disktab file to add an appropriate label and running "disklabel -w -B /dev/rda0c DSP5400S" which still gives an error message, but appears to install the label. I only found out that it installed the label by accident, wasting a bunch of time in the process. I created a striped volume across the 4 drives with the default stripe size of 256K. I read the rather interesting discussion within the man pages about the optimal stripe size and have a couple of queries. Firstly, the type of traffic that this 13.9GB filesystem will see will be mainly sequential reading and writing of large files. There will only be a few files (~2-30), each several gigs. (I'm fooling around with the seismic software at home, and typcal surveys can results in files many gigs in size). Given that FreeBSD breaks I/Os down into 64k chunks, would having a 64k stripe size give more parallelism? I'm seeing 4.4MB/s if I read from an individual disk, but only about 5.6MB/s when reading from the striped volume. Looking at the systat display, the 8k fs blocks do seem to be clustered into larger requests, so I'm not too worried about the FS block size. What have people observed with trying larger FS block sizes? Stephen -- The views expressed above are not those of PGS Tensor. "We've heard that a million monkeys at a million keyboards could produce the Complete Works of Shakespeare; now, thanks to the Internet, we know this is not true." Robert Wilensky, University of California To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message