On Tue, 26 Jul 2011 06:18:25 -0700 Steve Ellis <el...@brouhaha.com> wrote:
> >> Another point, even with your current config, if you > >> aren't doing data spooling you are probably slowing things down > >> further, as well as wearing out both the tapes and heads on the > >> drive with lots of shoeshining. > > (I'm asking as a person having almost zero prior experience with > > tape drives for backup purposes.) > > > > Among other things, I'm doing full backups of a set of machines to a > > single tape--yes, full backup each time, no incremental/differential > > which means I supposedly have just straightforward data flows from > > FDs to the SD. At present time I have max concurrent jobs set to 1 > > on my tape drive resource and no data spooling turned on. > > Would I benefit from enabling data spooling in this scenario? [...] > OK, perhaps I'm not the best person to ask, but here's what I do know: > > Even with only 1 job at a time, if you aren't able to deliver data to > the drive at its minimum streaming data rate (for LTO4, probably at > least 40MB/sec--possibly varies by manufacturer), then the tape > mechanism will have to stop, go back a bit, wait for more data, then > start up again--all of this takes time, and increases wear on the > tapes and drive heads. [...] > I hope this helps, Apart from giving me the knowledge of this mechanics, your message made me sit down and make some measures. So I discovered that my LTO-4 drive is actually faster to write (up to 10 times) than my local filesystems are to read (and I was absolutely sure it's the other way round). We're now considering implementing a raid0 for data spooling. Hence, thanks! ------------------------------------------------------------------------------ Got Input? Slashdot Needs You. Take our quick survey online. Come on, we don't ask for help often. Plus, you'll get a chance to win $100 to spend on ThinkGeek. http://p.sf.net/sfu/slashdot-survey _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
