Hi Kern, Thanks for your comments.
Kern Sibbald wrote: > By the way, increasing the Minimum Block Size is NOT the way to increase the > Maximum block size. In general one should *never* set the minimum block size > unless you have an older brain damaged drive. In increasing the Minimum > Block Size, you virtually guarantee to waste tape for no good reason. The > way to increase the maximum block size is to use the Maximum Block Size > directive, which I previously thought was rather obvious ... oh well. Oops. This was not obvious to me, despite having spent rather a lot of time studying the (excellent) documentation. and consulting my best friend, Google. I guess though that it's slightly more obvious now that you have pointed it out, and I have contemplated it for a while :) (and it should not be in Google for people like me with similar predicaments in future ;) > Unless you have a critical problem of speed, I don't particularly recommend > starting with block sizes other than the default. It would require a lot Unfortunately I do have a critical speed problem with bacula. I need to back up several terabytes of date in ~5 million files. With the default block size Bacula is *far* slower than our current Legato Networker at backing up this data to LTO 2 tape. Bacula *will not* write any faster to LTO 4 any faster than ~22MB/sec under any circumstances. Legato will write to tape at ~25MB/sec, or even a lot faster if it's easily compressible. I have tested Bacula using the fifo backup device to /dev/null and I believe I have comprehensively shown that there is no other bottlenecks, e.g. system speed or catalogue speed. I can pull in data at over 800Mbit/sec (over a GigE network) from our backup servers. > I would be interested to hear the experience of users who are using larger > block sizes. First about the throughput they get, but also about the number > of tape read errors they have, and any problems associated with running > multiple simultaneous jobs. I have so far backed up and restored data from running two multiple simultaneous jobs using a large block size. I will be doing much more testing while I try and get this system into production. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Bacula-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/bacula-devel
