From owner-freebsd-questions Sun Nov 8 21:11:03 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id VAA10638 for freebsd-questions-outgoing; Sun, 8 Nov 1998 21:11:03 -0800 (PST) (envelope-from owner-freebsd-questions@FreeBSD.ORG) Received: from allegro.lemis.com (allegro.lemis.com [192.109.197.134]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id VAA10632 for ; Sun, 8 Nov 1998 21:10:59 -0800 (PST) (envelope-from grog@freebie.lemis.com) Received: from freebie.lemis.com (freebie.lemis.com [192.109.197.137]) by allegro.lemis.com (8.9.1/8.9.0) with ESMTP id PAA11638; Mon, 9 Nov 1998 15:40:42 +1030 (CST) Received: (from grog@localhost) by freebie.lemis.com (8.9.1/8.9.0) id PAA14902; Mon, 9 Nov 1998 15:40:41 +1030 (CST) Message-ID: <19981109154041.J499@freebie.lemis.com> Date: Mon, 9 Nov 1998 15:40:41 +1030 From: Greg Lehey To: Bryce Newall , Jordan Krushen Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Tape backup questions References: <000801be0b7f$582dc7e0$0300000a@oblivion.purplemedia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.91.1i In-Reply-To: ; from Bryce Newall on Sun, Nov 08, 1998 at 06:25:13PM -0800 WWW-Home-Page: http://www.lemis.com/~grog Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Sunday, 8 November 1998 at 18:25:13 -0800, Bryce Newall wrote: > On Sun, 8 Nov 1998, Jordan Krushen wrote: > >> I've just added a Seagate TapeStor 4/8Gb SCSI drive to my 2.2.7 system, and >> I'm having a hard time figuring out how to have multiple sessions added to >> the tape. When using tar with /dev/nrst0 for two consecutive files, only >> the first file written to the tape remains. > > Tar doesn't allow you to create archive files on a tape. Rather, it sees > the tape itself *as* the archive file, and allows you to add files to and > extract them from the archive file. If you want to add to an existing > tape archive, you should theoretically be able to use the -A (append) > switch on the tar command. (I've never actually tried this, so I can't > verify that it actually works.) Otherwise, tar will erase the header on > the tape and start a new one. I don't know where you get this idea. tar does allow you to create archive files on a tape. That's what it's there for. You're talking about explicitly appending to a tar archive, which used to be popular, but is a Bad Thing with streamers. # tar clf /dev/nrst0 / # tar clf /dev/nrst0 /usr # tar clf /dev/nrst0 /home This will give you three backups with the contents of each of the file systems /, /usr and /home. In Jordan's case, I'm pretty sure that both files are there. Unfortunately, streamers are a little sloppy writing file marks, and it's possible for the following to happen with the tape written above: # mt -f /dev/nrst0 rewind # tar tvf /dev/nrst0 (list of / file system) # tar tvf /dev/nrst0 (nothing) # tar tvf /dev/nrst0 (nothing) # tar tvf /dev/nrst0 (list of /usr file system) # tar tvf /dev/nrst0 (nothing) # tar tvf /dev/nrst0 (list of /home file system). Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message