From owner-freebsd-questions Tue Dec 14 13:12:27 1999 Delivered-To: freebsd-questions@freebsd.org Received: from smtp4.fas.harvard.edu (smtp4.fas.harvard.edu [140.247.30.84]) by hub.freebsd.org (Postfix) with ESMTP id 90293154F7 for ; Tue, 14 Dec 1999 13:11:48 -0800 (PST) (envelope-from ahwang@fas.harvard.edu) Received: from is04.fas.harvard.edu (IDENT:ahwang@is04.fas.harvard.edu [140.247.30.104]) by smtp4.fas.harvard.edu with ESMTP id QAA09295 Received: by is04.fas.harvard.edu with ESMTP id QAA17085 Date: Tue, 14 Dec 1999 16:11:28 -0500 (EST) From: Adon Reply-To: Adon To: Mitch Collinsworth Cc: freebsd-questions@FreeBSD.ORG Subject: Re: DDS-4 set density woes In-Reply-To: <199912142102.QAA31206@benge.graphics.cornell.edu> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG it is nominally compressed (gzip default). in the past, i have seen that the hardware compression can squeeze some bits out of this. however, perhaps you are right. i should try the backup without hardware compression. my real question is concerning 'mt density' command. it seems to do nothing. i also have an exabyte 8mm drive. for that drive, the density shows up as simply "default". attempts to change it were also useless. thanks, adon On Tue, 14 Dec 1999, Mitch Collinsworth wrote: > > >i have a HP SureStore DAT40i (HP C5683A C908). it is a DDS-4 drive that > >purports to write to smaller formats such as DDS-2 or DDS-3. my problem > >is when i try to write to a DDS-2 tape. in its default configuration, i > >cannot write the full capacity of the tape (4 GB uncompressed). with > >hardware compression turned on, i get about 3.6 GB on a tape. > > Is the data you're writing already compressed before it goes to the > tape? Hardware compressing a file that is already software compressed > will actually end up making it bigger rather than smaller. From your > numbers above it sounds like this might be what's happening here. > > -Mitch > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message