Re: Can dbench be used for benchmarking fs?

[Nikita Danilov <Nikita@Namesys.COM>]

Andreas Dilger writes:
 > On Oct 07, 2003  16:42 +0400, E. Gryaznova wrote:
 > > I use dbench for benchmarking the file systems and some results are
 > > suspicious for me.
 > > :
 > > :
 > > :
 > > As the result: the measuring deviation is equal = 23.4062 - 15.7005 =
 > > 7.7057 or about ~38% from average value.
 > > 
 > > So, I have 2 questions :
 > > 1. Is there a way to avoid such big deviations on measuring a file
 > > systems throughput and to get more stable results?
 > > 2. Can dbench be used for benchmarking the file systems and if it is so
 > > -- what is the predictable error on the measuring?
 > 
 > Dbench is not a good filesystem benchmark, because it deletes all of the
 > files at the end.  Use something else for the filesystem benchmark - there

Err... What is wrong with deleting all files at the end? Or do you mean
it should mix file operations during run?

 > are lots of them (bonnie, iozone, mongo, etc).

But why variance is so large?

Another probably interesting observation is that dbench works faster on
ext2 if it is run directly after mkfs.ext2, that is, without reboot
between mkfs and mount.

 > 
 > Cheers, Andreas

Nikita.