From owner-freebsd-questions Wed Jan 3 21:53:11 2001 From owner-freebsd-questions@FreeBSD.ORG Wed Jan 3 21:53:09 2001 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from guru.mired.org (okc-65-26-235-186.mmcable.com [65.26.235.186]) by hub.freebsd.org (Postfix) with SMTP id B692F37B400 for ; Wed, 3 Jan 2001 21:53:08 -0800 (PST) Received: (qmail 21927 invoked by uid 100); 4 Jan 2001 05:53:07 -0000 From: Mike Meyer MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <14932.4035.440272.527525@guru.mired.org> Date: Wed, 3 Jan 2001 23:53:07 -0600 (CST) To: bdluevel@heitec.net Cc: questions@freebsd.org Subject: Re: a very dumb backup question In-Reply-To: <5495627@toto.iv> X-Mailer: VM 6.75 under 21.1 (patch 10) "Capitol Reef" XEmacs Lucid X-face: "5Mnwy%?j>IIV\)A=):rjWL~NB2aH[}Yq8Z=u~vJ`"(,&SiLvbbz2W`;h9L,Yg`+vb1>RG% *h+%X^n0EZd>TM8_IB;a8F?(Fb"lw'IgCoyM.[Lg#r\ Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG bdluevel@heitec.net types: > Mike Meyer wrote: > [...] > > Final comment - I'd recommend dump instead of tar, especially for the > > root file system, because historically it's tracked changes to the > > file sysystem and special files better than tar. > I've got an additional question concerning dump vs. tar: I seem to > remember that tar has an built-in limit of 8 GB per single backup, > because of some restriction in the tar file format. Is this true, and > what are the limits for dump and pax? And, given that backups sizes are > limited, how to best backup a 30 GB partition using 20 GB tapes? > Chunk-wise, with several 'tar' runs to the same tape without rewinding, > I assume? (Repartitioning into partitions with less than 8 GB each is > not an option in my situation, I'm afraid.) The limit on FBSD tar is 2GB. The gnu tar in the ports may have a larger limit. I have no idea about cpio or pax; if you test them to find out, please let us know. Dump is designed for dumping large file systems to smaller tapes. If you point it at a tape device, it will autodetect the end of tape (if the tape device supports it, if not you have to tell it), and prompt the operator to load another tape to the device. > Is there a way to let 'dump' backup less than an entire partition, such > as a directory and all its subdirectories? Nope. That provides a reason for creating partition - because you use dump, and want different backup strategies for two directories. http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message