Hi, Kern Sibbald wrote:
> For Chris: well if you consider 22MB/sec vs 25MB/sec *far* slower you have a > different concept of the world than I do. Yes, one might expect Bacula to be Sorry for not being very clear. It is "far" slower because we are replacing two LTO-2 tape drives with a single LTO-4. We could write to both of these LTO 2 at a combined rate of ~50MB/sec, but since I cannot get more than ~22MB/sec out of bacula writing to LTO-4 in its default configuration, it will be "far" slower overall :) > able to write to an LTO-4 faster than an LTO-2, but it many cases the tape > write time is not the big bottleneck in a Bacula backup. Indeed, and that is why I spent a very long time benchmarking various parts of bacula. I have seen that bacula will happily back up this data to the Fifo /dev/null device at about 100MB/sec. The moment I start using the tape again the figure drops to ~22MB/sec. Changing the block size in bacula is the only way I have seen that will increase performance. I have considered upgraded the kernel from 2.6.15 to 2.6.22. > You might get much more satisfactory results if you start with a different > premise from "Bacula *will not* write any faster to ... than ...". An That's a bit unfair IMO :) I *love* bacula am I am a very happy bacula user at home. That however is my conclusion, based on empirical evidence, after spending several weeks benchmarking bacula. Unfortunately I cannot immediately dump my results to the list for confidentiality reasons and NDAs (yes, it sucks...). I will however do my best to post further benchmarks to the list. > appropriate one might be "what are the things I can do to speed up the > backups?" or "what really are the bottlenecks", That is *exactly* what I posted here! :) > or "why can someone else > write at 72.28 M bytes/second, but my system does not?". Indeed, though it's not a particularly fair comparison: different types of LTO drives made by different manufacturers, with a different HBA, different connection (SAS vs SCSI), and a different kernel. ------------------------------------------------------------------------- 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
