From owner-freebsd-hardware Sat Jul 28 7:51:53 2001 Delivered-To: freebsd-hardware@freebsd.org Received: from polaris.we.lc.ehu.es (polaris.we.lc.ehu.es [158.227.6.43]) by hub.freebsd.org (Postfix) with ESMTP id DCCE537B405 for ; Sat, 28 Jul 2001 07:51:49 -0700 (PDT) (envelope-from jose@we.lc.ehu.es) Received: from v-ger.we.lc.ehu.es (lxpx142.lx.ehu.es [158.227.26.42]) by polaris.we.lc.ehu.es (8.11.1/8.11.1) with ESMTP id f6SEpkj02053 for ; Sat, 28 Jul 2001 16:51:47 +0200 (MET DST) Received: from we.lc.ehu.es (localhost [127.0.0.1]) by v-ger.we.lc.ehu.es (8.11.3/8.11.3) with ESMTP id f6SEmlw00751 for ; Sat, 28 Jul 2001 16:48:47 +0200 (CEST) (envelope-from jose@we.lc.ehu.es) Message-ID: <3B62D0CF.27C12B9@we.lc.ehu.es> Date: Sat, 28 Jul 2001 16:48:47 +0200 From: "Jose M. Alcaide" Organization: Universidad del =?iso-8859-1?Q?Pa=EDs?= Vasco - Dept. de Electricidad y =?iso-8859-1?Q?Electr=F3nica?= X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.2.12 i386) X-Accept-Language: es-ES, es, en-US, en MIME-Version: 1.0 To: hardware@FreeBSD.org Subject: DLT 4000 throughput and cstream Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hardware@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Hello, I am trying to maximize the data transfer rate to a DLT 4000 tape unit: ahc0: port 0xdc00-0xdcff mem 0xdffff000-0xdfffffff irq 10 at device 10.0 on pci0 sa0 at ahc0 bus 0 target 5 lun 0 sa0: Removable Sequential Access SCSI-2 device sa0: 10.000MB/s transfers (10.000MHz, offset 15) I am pipelining dump(8) to cstream (ports/misc/cstream), using this command line: dump 0fua - | cstream -v 1 -b 64k -B 1m -c 2 -o /dev/nsa0 However, I am getting what a I think is a too low transfer rate (compression is enabled on the DLT unit). This is what I get with iostat(8): sa0 KB/t tps MB/s 60.59 22 1.31 60.59 22 1.31 61.05 22 1.31 60.62 22 1.32 60.59 22 1.31 ... I tried several combinations of buffer sizes to no avail. Is this the expected throughput for a DLT 4000? If it is not, what could I do for obtaining higher data rates? (Note: the disk is fast -two IBM DTLA's mirrored with Vinum-, and the machine is an Athlon @ 800 MHz). TIA, -- JMA ****** Jose M. Alcaide // jose@we.lc.ehu.es // jmas@FreeBSD.org ****** ** "Beware of Programmers who carry screwdrivers" -- Leonard Brandwein ** To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message