> On Dec 2, 2015, at 10:04 AM, Alan Brown <a.br...@ucl.ac.uk> wrote: > > On 02/12/15 12:14, Paul Elliott wrote: > >>> Maximum block size = 2M >> >> Have you experienced any issues with that block size? > > Only when the drives/tapes are dirty and then you get excess errors on all > block sizes anyway. > > Because entire blocks are rewritten if there is an error, "tape waste" goes > up, but even with small blocks I've seen 75% of a tape lost to rewrites. > > You do need to watch those stats and react quickly if they're climbing - > where react quickly == put a cleaning tape in the drive asap. > > Unfortunately Bacula does not lend itself well to such interventions. > > > We had one major incident where a faulty HP LTO5 tape contaminated a drive > (beyond the point where a cleaning tape would work). That drive then > proceeded to contaminate the next 10 tapes loaded into it and those tapes > then cross-contaminated the other drives before we realised what was > happening. > > Tape manufacturer warranties don't cover consequential damages of this type > so this can get quite expensive to sort out. (The maintenance agreement on > the drives covered it, but it was still highly disruptive) > > The more general problem is environmental cleanliness. Human skin dust (which > is almost all dust in a household or office environemnt) is one of the worst > possible contaminants for tapes because it's slightly greasy. > > Neither standalone or library manufacturers pay any attention to this issue, > with non-filtered inlets and enclosure fans invaribly pulling air through the > tape mechanisms. > > If at all possible, tape drives/libraries should be in heavily filtered > environments with as few humans around as possible. > I strongly recommend against having them in a server room if you can avoid > it. A dedicated closet/room is better and ideally your data safe should be > colocated with the library (less handling, less risk). > > I'd recommend active air filtration (scrubbers) and humidity control if you > can get it too. The cleaner the environment, the fewer problems you'll have > with the drives. > > As an example of this: When building work was performed in the server room, > despite the library being partitioned off with plastic sheeting, every single > drive failed within 6 weeks.
The spare bedroom in my apartment does not meet these specifications. I'll look at adding filters from http://www.demcifilter.com/ before powering it up. — Dan Langille http://langille.org/ ------------------------------------------------------------------------------ Go from Idea to Many App Stores Faster with Intel(R) XDK Give your users amazing mobile app experiences with Intel(R) XDK. Use one codebase in this all-in-one HTML5 development environment. Design, debug & build mobile apps & 2D/3D high-impact games for multiple OSs. http://pubads.g.doubleclick.net/gampad/clk?id=254741911&iu=/4140 _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
