Hello, On Tuesday 29 July 2008 15:22:03 T. Horsnell wrote: > What: > That Bacula be modified to enable the simultaneous use of multiple tape > drives, either as a bunch of freestanding units or as multiple drives in > an autochanger. > > Why: > For me personally, this would permit faster simpler backup of a large > single filesystem. I have a two-drive LTO4 tapechanger and at present, > in order to utilise both drives at once, I have to create two jobs each > of which backs up part of the filesystem. This is not optimal as the two > subparts can change size radically, meaning that one drive may spend > much of its time idle. I also have to split my tapes into two pools, one > for each job. > I have seen one other similar request to the users list recently, > whereby a user had a bynch of freestanding drives which he wanted to > preload with a set of tapes once a week, and then have Bacula > automatically organise his backup over the tapes as it saw fit. > This may make a cheap alternative to a tapechanger. > > A device pool maybe?
Technically I don't know how to do this project. The SD has blocks of data coming in from the FD, and sending those blocks to multiple drives would be extremely difficult to track -- I am not even sure how. Currently, they are either sequential (if spooling is on) or at least written in order to a single drive, so it is very easy to track and find them for restores. In addition, I don't think it is possible for any existing network connection to run fast enough to drive an LTO4 tape drive at full speed, so this project seems to add a lot of complexity to Bacula to give no improvement in performance. If I am wrong about the network connection and an LTO4, please show me the math :-) For the moment I cannot accept the Feature Request. If you can give complete details of a design for tracking the blocks written to multiple tapes and how to send them back to the FD in the same order, and if you can show with a simulation that we would actually gain something, then you can resubmit it, and I will reconsider adding it to the projects. After than, either someone must submit a patch or the Bacula users vote and it becomes a top rated project, in which case one of the developers would surely work on it. Best regards, Kern PS: Normally, I don't veto a Feature Request even if I am not much in favor of it unless it involves license problems (using proprietary interfaces) or is technically not possible as is the current request as written. ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Bacula-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/bacula-devel
