From owner-freebsd-questions Sat May 26 12:10:59 2001 Delivered-To: freebsd-questions@freebsd.org Received: from web9502.mail.yahoo.com (web9502.mail.yahoo.com [216.136.129.132]) by hub.freebsd.org (Postfix) with SMTP id 16F1B37B424 for ; Sat, 26 May 2001 12:10:57 -0700 (PDT) (envelope-from felix_hdez@yahoo.com) Message-ID: <20010526191056.97775.qmail@web9502.mail.yahoo.com> Received: from [152.2.142.108] by web9502.mail.yahoo.com; Sat, 26 May 2001 12:10:56 PDT Date: Sat, 26 May 2001 12:10:56 -0700 (PDT) From: Felix Hernandez Subject: Slower tape drive when compression off To: freebsd-questions@FreeBSD.ORG MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Hi, I have a Quantum DLT8000 tape drive (40/80 GB), and I'm puzzled by the following fact: writing the tape in compressed mode (mt comp on) is faster (4 MB/s) than in uncompressed mode (mt comp off, 2 MB/s). I use tar (1.13) for my backups, and the tape is attached to an IBM Netfinity 7100 running FreeBSD 4.1. I have already tried a large and fixed blocksize (mt blocksize 10240, tar -b 20), but it didn't help. Do you know why this happens? How can I fix it? I don't want to use compression, since the data is already gzipped, and recompressing it wastes 5 GB. Regards, Felix Hernandez. --- /kernel: sa0 at ahc2 bus 0 target 5 lun 0 /kernel: sa0: Removable Sequential Access SCSI-2 device /kernel: sa0: 20.000MB/s transfers (10.000MHz, offset 8, 16bit) __________________________________________________ Do You Yahoo!? Yahoo! Auctions - buy the things you want at great prices http://auctions.yahoo.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message