Date: Sat, 24 Apr 2004 12:06:43 -0400 From: Richard Coleman <richardcoleman@mindspring.com> To: Don Lewis <truckman@FreeBSD.org> Cc: julian@elischer.org Subject: Re: Testing Tar (was Re: bad news for bsdtar..) Message-ID: <408A9093.2050409@mindspring.com> In-Reply-To: <200404240540.i3O5eA7E053079@gw.catspoiler.org> References: <200404240540.i3O5eA7E053079@gw.catspoiler.org>
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Don Lewis wrote: >>>At least the -current version of tar skips reading the >>>data when it is writing to /dev/null. >> >>A-ha! That explains a few of the odd timings I've seen. >>I wonder why it does that? (Other than to look good on >>benchmarks, of course. ;-) > > > This speeds up Amanda quite a bit. Amanda will run tar with the > --totals option as well as other options to specify either full or > incremental backups multiple times for each file system that it backs > up. It does this to plan the best mixture of full and incremental > backups. If tar actually read the data from disk each time, the > planning phase would take a *lot* longer, and would thrash the disk a > lot more. Until libarchive gets support for sparse files, it's probably better to stick with gtar or rdump with Amanda. But the concept of a version of Amanda that natively uses libarchive is very cool. It seems like a natural target. Richard Coleman richardcoleman@mindspring.com
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