Monthly Status Updates/June 2007

June saw the release of Amanda 2.5.2p1 on June 6, a patch release which was thoroughly tested with the help of the Platform Experts and many users from the mailing lists and forums. This patch release has proven quite stable, and development has shifted to feature development for the next release.

Community Choice Award

SourceForge, the open source hosting service which supports Amanda, announced its 2007 Community Choice Awards. Please vote for Amanda in the Best Tool or Utility for SysAdmins category.

Wiki Changes

• Marc Muehlfeld provided a link to a useful script for performing backups of MySQL databases.
• Harald Schioeberg provided Lto-barcode, a perl script to generate barcode labels for LTO Tapes. Chris Hoogendyk suggested barcodewriter, a PostScript-based barcode utility, as a more general solution.
• Erik W wrote a detailed How To:Install Amanda Server on AIX.
• Harald Schioeberg provided Chg-multiplex, a wrapper to use multiple Amanda configs in a single restore operation.
• Paul Bijnens contributed a multitude of minor edits all over the wiki, increasing readability and clarity.
• Dustin J. Mitchell refactored Stefan G. Weichinger's file driver into How To:Set Up Virtual Tapes, FAQ:Should I use a holdingdisk when the final destination of the backup is a virtual tape?, How To:Migrate Virtual Tapes to Real Tapes, and How To:Restore from Virtual Tapes.

Forums Discussions

Many users had questions about configuring Amanda to their needs. Most questions were about communication problems, and were quickly addressed. Among the more unusual questions were the following.

• tamiral asked several interesting questions:
  • How can I verify that AMANDA has successfully backed-up files? -- Shailen Patel suggested using amrecover to test a full restore, which is more thorough than the tape verification performed by amverify.
  • I'm concerned that because my defined tape size is larger than the amount of diskspace I have... -- Shailen Patel and Dustin J. Mitchell responded that yes, this could cause a problem, and referencing wiki pages describing the optimal configuration.
  • Basically, I'd rather use 'dd' for those kind of jobs (even unmount the filesystem so it won't change), but I guess I can't with AMANDA. What is the recommended dumptype for this kind of backup...? -- Paddy Sreenivasan suggested a dumptype with always-full, compression off, and encryption off.
• George Reeke had a client machine which exceeded Amanda's connect timeout because its hard drives took too long to spin up. Paddy Sreenivasan suggested increasing ctimeout and etimeout.
• mickeyn has clients with dynamically-assigned addresses. Marc Muehlfeld suggested using static IP assignments in the DHCP server as a way to stabilize the clients' addresses.

Mailing List Discussions

• Charlie Reitsma asked if any work had been done on migrating dumps from vtapes to real tapes. Dustin Mitchell, Gene Heskett, and Jon LaBadie replied with some pointers, and Charlie started work on an implementation to suit his needs.
• Philip Weber sparked an interesting conversation about Amanda automatically detecting disks that are not in Amanda's disklist and thus are not being backed up. While the problem is difficult to solve in the general case, a few specific solutions were suggested as wrappers around Amanda.
• Jon LaBadie tried running amtapetype on a vtape, and the results touched off an interesting discussion on what amtapetype should do in such a situation.
• Marc Muehlfeld wondered how Amanda can fill a tape to more than 100% capacity. Cyrille Bollu and Paul Bijnens answered, pointing out that tapes differ in actual capacity, and that Amanda only uses the tapelength for planning purposes, but will happily consume any extra space it finds.
• Robert P. McGraw, Chris Hoogendyk, and Brian Cuttler discussed the relative merits of hardware and software compression, noting that Amanda has a difficult time calculating the number of dumps it can fit on a tape when hardware compression is enabled.
• Rudy Setiawan asked for advice setting up a large disk-to-disk configuration, and prompted a lengthy discussion about calculating space requirements of a configuration, optimizing a system for fast disk-to-disk backups, and ensuring sufficient redundancy for backup data in such a configuration. Chris Hoogendyk hijacked the thread to consider ways of running incremental backups only over a weekend.
• Sebastian Marten asked about the relationship of runtapes to tape_splitsize. Marc Muehlfeld replied to say that splitting dumps across tapes is impossible with only one tape (runtapes=1). Sebastian does not have a changer, but nightly backups are larger than his media (DVD-RAM), so Marc suggested using multiple DVD drives, spooling some dumps to holding and flushing between dumps, or using chg-manual to use two DVD-RAMs per dump.
• Phillip Weber wondered if he could run two Amanda configs against the same tape changer. Ian Turner, Joshua Baker-LePain, and Jean-Francois Malouin chipped in to say that this configuration could work, but that some extra machinery was required to ensure that only one configuration was making requests of the changer at any given time.
• "fedora" saw "file changed as we read it" in his backup report for MySQL data files. This triggered a lengthy discussion:
  • Oliver Nicole pointed out that this is just a "STRANGE" warning, not an error, and that it is caused by tar being unable to back up a large file while that file is changing.
  • Marc Muehlfeld, Bruce Thompson and Linda Pahdoco offered pointers to scripts for backing up MySQL databases via mysqldump or mysqlhotcopy.
  • Dustin J. Mitchell pointed out that ZRM for MySQL is designed to back up MySQL databases without making textual dumps.
• Glenn Gillis had trouble with estimates failing on a partition with a very large, constantly changing file. Kevin Till and Oliver Nicole agreed that this was a result of a bad tar version returning an incorrect status.
• Paul Crittenden discovered an error in the file-locking support detection, which caused Solaris builds of Amanda to use no file locking at all. Chris Hoogendyk, Jon LaBadie, Jean-Louis Martineau, and Dustin J. Mitchell chased down a solution.
• Alan Jedlow discovered a bug in chg-zd-mtx, which was fixed by Dustin J. Mitchell.
• Jean-Francois Malouin had trouble with estimates timing out after 6 hours. Jean-Louis Martineau provided a patch to reset this limit for each estimate.
• Jordan Desroches had errors backing up a subdirectory of an NFS mount. Paul Bijnens, Dustin J. Mitchell, Olivier Nicole, and Jean-Louis Martineau contributed advice, eventually determining that the amanda user did not have adequate permissions on the subdirectory.
• Harald Schioeberg had trouble with Amanda not finishing when /tmp was full. Dustin J. Mitchell pointed out that many of the external programs on which Amanda relies use /tmp, and that the failure most likely occurred there.
• Fedora had trouble getting client-server communication to work, and the eventual resolution was that host-based firewalls like netfilter and iptables can interfere with Amanda's communication.
• Ladislav Michnovic alerted amanda-hackers to a regression in SUSE Linux, reported by Matthias Andree, relating to multihomed machines. The issue has stalled without any feedback from Matthias.

Code Development

Most of the development work in June was focused on testing and bugfixes for the 2.5.2p1 release. Subsequent to the release, Dustin J. Mitchell committed a number of minor changes that had been queued up awaiting release, including improved holding-disk management, streamined internationalization, and debugging support.

• Jean-Louis Martineau
  • fixed a bug discovered by Marc Muehlfeld where hosts running in a mixed IPv4/IPv6 environment would encounter errors (r397)
  • fixed a bug discovered by Christopher McCrory where amfetchdump sent messages to stdout, corrupting the resulting tarfiles (r410)
  • fixed spurious detection of GNU Tar's backup as a dump-compatible program (r411)
• Dustin J. Mitchell
  • streamlined the handling of exit statuses from the programs Amanda invokes (r420)
  • fixed broken file-locking support on Solaris, as reported by Paul Crittenden (r422)
  • clarified the error message resulting from incorrect entries in .amandahosts (r423)
• Franz Fischer submitted a patch to make amtapetype close the tape device after rewinding, to work around a hardware/OS bug on his system. The patch was modified and committed by Jean-Louis Martineau (r416)