Hi, 31.08.2007 11:31,, Chris Howells wrote:: > Hi, > > I am trying to figure out whether bacula supports multiplexing multiple > simultaneous backup jobs to the same tape - having googled, the results > are inconclusive :)
The only correct answer is Yes. > I am currently playing with an LTO-4 tape drive which has a raw data > transfer rate of 120MB/sec. Clearly any single machine is going to have > difficulty in maxing out the drive. I'd therefore like to try running > backups from multiple machines to the drive simultaneously. > > If it does support multiplexing, what kind of options do I need in the > config files? I currently have bacula talking to the drive, but I was > getting 25MB/sec backing up a 10gig file of zeros (admittedly from a > single SATA disk so that's not too surprising), but just 10MB/sec doing > a trial backup of a home directory server over the network, from a > pretty fast RAID. We get better performance from our current LTO-2 > drives and Legato Networker :( First you need to enable job concurrency. That will require you to add "Maximum Concurrent Jobs" in several places, which are well documented. Furthermore, you might have to change the jobs and schedules so that jobs actually run in parallel. The schedules are clear, I think, but keep in mind that Bacula only runs jobs of the same priority at once. Then you've got to decide how Bacula should multiplex. The simple solution requires no further configuration; jobs will write their blocks to tape as they arrive. This is simple, but restoring can take lots of extra time due to many unneccessary tape positionings and possibly reading unnecessary data. The (almost always) better solution is to enable spooling with a reasonable spool space - a few hundred GB, preferrably. This costs more disk space (which is comparable cheap), but then, Bacula will spool as much of a job as is possible and write that en block to tape. The time it takes for a single backup can increase, but the overall throughput of several jobs will be better, and data from each job is kept more or less together on tape, allowing faster restores. In this scenario, the speed of your spooling file system will probably be the limiting factor for tape speed, so you better implement a fast RAID for spool space. Imagine one job is despooling data, while several others write data from the client to the spool area and you get an impression of the kind of disk subsystem you need. Arno > Thanks. > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. > Still grepping through log files to find problems? Stop. > Now Search log events and configuration files using AJAX and a browser. > Download your FREE copy of Splunk now >> http://get.splunk.com/ > _______________________________________________ > Bacula-users mailing list > Bacula-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bacula-users -- Arno Lehmann IT-Service Lehmann www.its-lehmann.de ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
