Adam Goryachev schrieb: (...)
> Recently some optimisations were discussed that made a significant > difference: > 1) Mount your filesystem with noatime or equivalent so every time > backuppc looks at a file it doesn't need to write the new atime. The > atime is not relevant to backuppc anyway. You might also be able to > disable the atime update for directories nodiratime noatime implies nodiratime, so there is no need to specify both as a mount option. > 2) There was mention of disabling some feature of RAID5 (maybe bitmaps > or something) which I recall giving a 20% improvement. > > 3) When the filesystem is created (if using ext3) then apparently there > are some extra options/care that should be used when putting it on a > RAID5 array so that one drive doesn't get all of the <something> on it. > > Hmmm, is there a page on the wiki for performance enhancing backuppc? Is > there a disk section on that? Can someone who knows the answers to the > above add some bits to it, it would likely help a number of people. > > Oh, then there is the rsync performance improving checksum-cache or > similar which might also help you if you are not already using it. It was discussed that splitting a large archive into several smaller ones might be a good idea - no one answered why. So here is why ;) Before rsync transfers anything, it builds a list of files. Basically, rsync reads a list of local and remote directories/files, compares it with its algorithms, and starts the transfer. For large sites, where there are lots of files and directories it can take *hours* just to build an initial list. *Hours*. It is worth to note that when rsync builds its list, no files are being transferred. So only here several hours are wasted - nothing was copied, no new files were added to the backup. By splitting the archive into several smaller ones we effectively reduce this time (of rsync building the list). Of course, when we add up the time of building the separate, smaller lists, it will be roughly the same as building one large list. What we save, is these several hours where BackupPC/rsync would waste for just building one, large list. It is also worth to mention that rsync 3.0.0 can start the transfer as soon as it connects, while the file list is being built in the background. This can be a severe speed-up for bigger sites. Unfortunately, BackupPC still uses rsync 2.6.x and therefore, can't benefit from this new rsync feature. -- Tomasz Chmielewski http://wpkg.org ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ BackupPC-users mailing list [email protected] List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/
