> On 08/26/10 05:04, m...@free-minds.net wrote: > > Hello, > > I think this is a common question but i didnt found a proper answear in > > the documentenation, if there is already one please let me know :) > > > > So we have now successfully set up our Bacula Servers and everything is > > now running more or less... > > But we have some questions: > > 1) do we really need to spool? We are not writing to real tapes, we have a > > filesystem as backend (ext3 over glusterfs). > > If you're using a disk backend, honestly, there is really no reason > whatsoever to use spooling.
A small spool (eg a few GB) is useful to avoid fragmentation on your backup disk. It will slow down the backup a bit, but not as much as you'd think if the spool is fast (eg flash or 10KRPM disks) and the backup medium is slow (eg USB2 attached). Fragmentation on backup media when you are doing more than one concurrent backup very quickly reaches several 9's. A hdparm on my USB2 attached 5400RPM 2.5" backup disk maxes out at 31MB/second read performance. That's slower than any current tape drive. hdparm on the 7200KRPM RAID5 disk array (admittedly, read speed and not write but half the time you are reading the spool at least) is 350MB/second. Over 10x the speed. If the backup disk was eSATA attached and 7200RPM or faster then the performance impact of spooling would become more pronounced but at the moment it's insignificant. James ------------------------------------------------------------------------------ Sell apps to millions through the Intel(R) Atom(Tm) Developer Program Be part of this innovative community and reach millions of netbook users worldwide. Take advantage of special opportunities to increase revenue and speed time-to-market. Join now, and jumpstart your future. http://p.sf.net/sfu/intel-atom-d2d _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users