From owner-freebsd-hardware Fri Jan 31 9:23:14 2003 Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D617B37B401 for ; Fri, 31 Jan 2003 09:23:12 -0800 (PST) Received: from testmail.wolves.k12.mo.us (testmail.wolves.k12.mo.us [207.160.214.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id 19EF143F93 for ; Fri, 31 Jan 2003 09:23:11 -0800 (PST) (envelope-from cdillon@wolves.k12.mo.us) Received: by testmail.wolves.k12.mo.us (Postfix, from userid 1001) id E0A78CD24; Fri, 31 Jan 2003 11:22:59 -0600 (CST) Received: from localhost (localhost [127.0.0.1]) by testmail.wolves.k12.mo.us (Postfix) with ESMTP id DBD61CD23; Fri, 31 Jan 2003 11:22:59 -0600 (CST) Date: Fri, 31 Jan 2003 11:22:59 -0600 (CST) From: Chris Dillon To: joe mcguckin Cc: hardware@FreeBSD.ORG Subject: Re: DLT tape not streaming In-Reply-To: Message-ID: <20030131111850.I4402@duey.wolves.k12.mo.us> References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII 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 On Thu, 30 Jan 2003, joe mcguckin wrote: > Our DLT-7000 tape drive does not stream continuously - there's quite > a bit of shuttling back and forth. > > Are there any SCSI parameters I can tweak to improve it's > performance? Assuming you can actually read the data off the disks and/or network fast enough, if you can't seem to feed the drive enough data across the SCSI bus to keep it streaming then you aren't using a large enough block size. If you're trying to feed the drive 512-byte blocks, that is likely not going to work. I would recommend somewhere between a 32KB and 128KB block size for a DLT drive. I use 64KB blocks with my DLT1 drive, but I think that is also the maximum block size in Windows NT, which is what the drive is attached to. I think FreeBSD supports up to 128KB blocks. -- Chris Dillon - cdillon(at)wolves.k12.mo.us FreeBSD: The fastest and most stable server OS on the planet - Available for IA32 (Intel x86) and Alpha architectures - IA64, PowerPC, UltraSPARC, ARM, and S/390 under development - http://www.freebsd.org No trees were harmed in the composition of this message, although some electrons were mildly inconvenienced. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message