On Tue, Apr 01, 2008 at 09:56:27AM +0200, Ronny Aasen wrote: > > So, it works with NFS ? > > Yes it works with NFS. But it scales poorly > > I am running a small installation. only 23 hosts. on a 6TB nfs nas, > using mostly gigabit ethernet. > 5.9T 3.4T 2.6T 57% /var/lib/backuppc > > speed varies between 1 MB/sec and 8MB/sec with the average laying about > 3MB/sec for a full backup. and 0.5MB/sec for incremental > > cpu is often in iowait during backups. > > mark: this is all server hardware intel server gigabit network cards. > and lsi sas raid controller with sata 500GB raid edition harddrives
My impression is that it scales so badly because there are a lot of seeks between pc backup directories and the pools. The MD5 hashing distributes files randomly over the pool, so you end up looking at another place on disk for each file which involves seeking. I've got a Dell machine here with PERC5/i (which is by no means fast) and I also have three WD RAID Edition 500 GB SATA drives. Somehow it doesn't fit very well. I'm seeing I/O starvation, throughput is at about 300-500 kB/s during backups and device utilisation is at 100% (measured with iostat). I've got a second RAID5 on the same controller, but with three 750 GB SATA drives (Hitachi HUA721075KLA330). This seems to perform better, but mainly takes large files, so the seeking is not a problem. I wish there was a "swap file systems" operation so I could test how BackupPC performs on the second RAID. Hm. Maybe I'll use a weekend to copy the raw xfs file system to another logical volume? But then there's still the file system tuning issue. Or I'm just suffering partition misalignment so FS accesses cross RAID stripes too much? So much questions, so little time... :-( Or maybe I've just got too little memory? I see only 600MB of "cached" memory while the backup (our largest one: 2.9 million files, 120 GB) takes 640 MB plus 480 MB for each of the BackupPC_dump processes (using rsync). The machine has 2 GB. Bye, Tino. -- „Es gibt keinen Weg zum Frieden. Der Frieden ist der Weg.” (Mahatma Gandhi) www.craniosacralzentrum.de www.forteego.de ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ 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/
