Date: 12 Oct 1999 02:03:26 +0200 From: naddy@mips.rhein-neckar.de (Christian Weisgerber) To: freebsd-questions@freebsd.org Subject: Re: backup method reccommendation? Message-ID: <7tttse$1nc2$1@bigeye.rhein-neckar.de> References: <19991009123827.E12733@uberhacker.org> <7tr8no$89m$1@bigeye.rhein-neckar.de> <19991011112242.R78191@freebie.lemis.com>
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Greg Lehey <grog@lemis.com> wrote: > dump and restore are fine if you really only ever want to restore to > the same operating system. They're not portable across different > systems. I consider that an open question. Limited empirical evidence shows FreeBSD/Linux/Solaris dumps to be compatible. > For this reason, I prefer tar. The POSIX ustar format is rather limited. GNU tar uses extensions of its own that are *not* portable. A file name >100 chars is enough. Talk to Jörg Schilling if you want to learn just what a mess the tar format is. (If I wanted to use a tar-like program for backup purposes, I'd use cpio or pax. The SVR4 cpio format doesn't have the device and pathname limitations of the tar one, and it is reasonably portable, being understood by SVR4 cpio, BSD pax, and GNU cpio.) tar has difficulties handling sparse files (-S works pretty well but makes the archive non-portable of course), no built-in buffering, it touches the access time of all files, and the archive has no central index. > > tar as shipped with FreeBSD can't backup all devices in /dev. > Correct. The version in -CURRENT (and thus in a -RELEASE coming soon) > can do this, however. When has this been added? This is -CURRENT from a month ago: naddy@bigeye[~] tar -cf /dev/null -C / dev tar: dev/rsa0.ctl: minor number too large; not dumped It's my understanding that the minor number field in the GNU tar format is simply insufficiently sized to accommodate all possible FreeBSD device numbers. > > Customarily tapes are rewound at the end of the backup. > > That depends on what you ask for. I meant: customarily, the operator rewinds the tape at the end of the backup. > It's possible to remove a QIC tape without rewinding it, but DDS, > Exabyte and DLT all have to be rewound before you can remove them. I strongly suspect my QIC drive to rewind tapes when they are *inserted*, although I haven't exactly researched the issue yet. -- Christian "naddy" Weisgerber naddy@mips.rhein-neckar.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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