From owner-freebsd-questions Tue Jul 25 13:31:44 2000 Delivered-To: freebsd-questions@freebsd.org Received: from smtp.nwlink.com (smtp.nwlink.com [209.20.130.57]) by hub.freebsd.org (Postfix) with ESMTP id 3469837B864 for ; Tue, 25 Jul 2000 13:31:38 -0700 (PDT) (envelope-from jcwells@nwlink.com) Received: from utah (jcwells@utah.nwlink.com [209.20.130.41]) by smtp.nwlink.com (8.9.3/8.9.3) with SMTP id NAA19023; Tue, 25 Jul 2000 13:31:32 -0700 (PDT) Date: Tue, 25 Jul 2000 13:43:35 -0700 (PDT) From: "Jason C. Wells" X-Sender: jcwells@utah To: Meagan Jia Pi Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Backup Solution In-Reply-To: <06b301bff65c$c4d12c10$e293c83f@meagan> 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 On Tue, 25 Jul 2000, Meagan Jia Pi wrote: > I don't quite understand how 490GB data can fit in a 70GB DLT tape. How do > you > do that? You are right, if such a big compression can be achieved, a robot > is not necessary > al all! Great news! OK. Take a 35 GB DLT with a drive that does 2-1 compression. That gives 70 GB on a tape. Assume you have a dumpcycle of 1 week. This means that at least one level 0 dump must be done each week. Assume you rotate one tape per day for each day in the week. That gives you a total of 490 GB (7*70) GB (minus fudge factor) of tape capacity. The backups are spread over several days. This is merely one example of how to set up a system that is very flexible. I did not include level 1-9 dumps. I did not include a better tape rotation method. Mixing in multi-level dumping and tower of hanoi tape rotations can allow you to keep safe backups on a minimal amount of tape. To read up on amanda, there is a chapter all about it on the net. See amanda.org for more details. Thank you, Jason C. Wells To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message