Christoph Litauer schrieb:
> Thanks a lot Adam!
> In the meantime I discussed my problem on the xfs mailing list. We are 
> not finished yet, but adding mount option "nobarrier" reduced my 
> performance problems significantly. I am still in contact to clarify if 
> it's possible to optimize the usage of inode allocation groups. We will 
> see ...
> 
> To get a better base for further discussions, I did a few benchmarks 
> using bonnie++:
> 
> bonnie++ -u root -f -n 10:0:0:1000 -d /backuppc -s0
> 
> result for file creation per second: 5501 (sequential)
> result for file creation per second: 6430 (random)
> 
> Without option nobarrier I had 137 files/second ..
> 

Well ... this was the good news ...
... now the bad ones ...

This morning, 2 backup processes were still running. strace'ing one 
client process, one can see that rsync is waiting for sending data 
(select). strace'ing the servers process (BackupPC_dump), one can see 
that it creates tons of directories ... which is correct as I have 
learned as the dump is an incremental one.
But: BackupPC_dump only creates about 60 directories per second 
(regarding the number of used inodes). A bonnie++ benchmark _in 
parallel_ on backuppc's filesystem reports 1450 files/directories per 
second (minimum).

Some of my clients have filesystems containig about 250,000 directories. 
So the creation of the directory tree lasts about 1.5 hours for each 
client plus the time for transfering the backup data. I think this maybe 
the reason why my backups are still running in the morning ...

What are your directory creation rates regarding BackupPC_dump?


-- 
Regards
Christoph
________________________________________________________________________
Christoph Litauer                  litauer AT uni-koblenz DOT de
Uni Koblenz, Computing Center,     http://www.uni-koblenz.de/~litauer
Postfach 201602, 56016 Koblenz     Fon: +49 261 287-1311, Fax: -100 1311
PGP-Fingerprint: F39C E314 2650 650D 8092 9514 3A56 FBD8 79E3 27B2


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