Comment 253 for bug 131094

Today Yan Li wrote:

> Tobias Oetiker:
>
> Thank you very much for the update. I'm a bit surprised to see the
> single-reader on ext4 is worse than that on ext3. I'm to postpone the
> upgrade of my systems to ext4. I dare not using data=writeback yet.
>
> I'm a bit confused about why you ran this on a RAID6 system. The RAID
> card/driver might affected the performance in a way yet to be
> understood. IMHO the less layers between Linux kernel and hard drive,
> the better we can understand the kernel I/O scheduler/fs etc.
>
> Again, thank you for the great data.

As you can see from the results, running the test on a RAID6 gives
vastly different results. Fact is that for reliability we are
running all our servers on RAID6, so this is the configuration I am
most interested to see working well ... good performance on a
single disk does not help me much ... (I am glad to see that it is
even worse to some extent, than my RAID6 performance).

I think at the heart of the problem lies the fact benchmarks focus
on single aspects of subsystems which then get optimized without
looking at the overall impact.

cheers
tobi

>
>

--
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch <email address hidden> ++41 62 775 9902 / sb: -9900