BackupPC is being surprisingly slow even for incrementals. This appears to be tied to the rsync backend in some fashion.
Here's an example. It took 5 *HOURS* to run an incremental over a machine in which the total incremental size was 2383 files of 616MB. This is fairly typical. Examining processes with strace and lsof, it appears that the BackupPC unnecessarily is opening every single file from the existing backup sets on the server -- even if they hadn't changed a bit. I am using cpool with rsync checksum caching -- the latter turned on hoping it would help, but it didn't. The most recent full backup of this system took 56 *HOURS*, though that may be before checksum caching had a chance to kick in. The first full backup of it took only 17 hours, and I didn't do anything like copy tons of new stuff to it or anything. That most recent full backup had 787941 files which was 444GB. From what I have seen to date, tar doesn't have this problem. However, due to the limitations of the tar backups documented at http://bit.ly/fbiCyh I really wish to avoid using tar for backups wherever I can. The system being backed up in this example is a Core 2 Duo running Debian squeeze, 8GB ram. The BackupPC server is a dual-core Pentium E6500 2.93GHz. The backup disk is a 1TB USB drive, ext4, running through LUKS encryption since it goes offsite. The USB bit seems to contribute more to slowness than the LUKS bit on this system. But the end effect is that if BackupPC is being non-smart about how it accesses the disk on the server side, this will be magnified by the USB interface. What can be done to fix this? Combined with the problem of very slow performance for large files with rsync [1] (which did NOT refer to a problem with slow disks), I am starting to doubt whether the rsync backend is really useable yet. Thanks, -- John [1] http://bit.ly/hCJ7Gj ------------------------------------------------------------------------------ Free Software Download: Index, Search & Analyze Logs and other IT data in Real-Time with Splunk. Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ 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/
