Phil Stracchino wrote: > It is possible right now to open more than one file-based volume at a > time. > You simply need to define multiple storage devices under the same > storage daemon; each device can have one volume open at a time.
Yep. My suggestion was merely a way around the inconvenience and configuration bloat required to do this at present. I'm saying it shouldn't be neccessary to go through all that just to achieve concurrent disk writes. > However, if multiple volumes are being written at a time, this merely > exchanges volume interleaving for disk fragmentation. Depends a lot on the file system and storage in use. I'm using a file system with sensible delayed allocation policies, which tends to control fragmentation. I'm also using a striped RAID-6 volume across eight 1TB disks, which means access patterns are going to be somewhat random anyway. Fragmentation just isn't a big issue. > The odds are good > the data will actually end up in the same places on disk; it will just > appear, from the point of view of scanning volumes, to be unfragmented, > because the disk system hides the fragmentation from you - exactly as it > is supposed to. As previously mentioned, this can be overcome > essentially only by using a complete custom filesystem and disk driver > that treats disks like tapes. Actually, you can do a pretty good job just by using posix_fallocate(...) to inform the file system of how much space you expect to need. The sd doesn't currently appear to use posix_fallocate(...) at all. > Bacula-5 does not automatically delete expired disk volumes; it does > contain a feature to automatically truncate them to zero bytes. Note > that this feature is dangerously broken in 5.0.0 (in which it was a new > feature), and should not be used in that version; if you want to use the > volume truncation feature, you must run 5.0.1 or later. > > Automatic volume deletion can be handled fairly simply using an admin > job that runs a script to delete expired volumes; I've attached mine as > an example. Of course. I do much the same thing myself. I'm just suggesting that perhaps this sort of thing shouldn't have to be built by each Bacula user, but perhaps be built in to the system to make it a bit more practical and convenient? I don't mean to come off as a grumpy/demanding user. I'm not saying "you should do this!", I'm seeking comments and opinion on whether these things are worth doing. I may well tackle them myself if so, I just don't want to waste my time on things that will get rejected. I do, though, think Bacula's usability could use a lot of improvement. I'm trying to throw around some ideas about some things that might help, based on my own experiences wrangling it to get it to do what I need. -- Craig Ringer ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
