RE: (Severe?) Performance issues with ext3 created on RAID5 with partman

["Leo Bogert" <spam-goes-to-dev-null@gmx.net>]

Lennart Sorensen wrote:
> What speed does ext3 get on a single drive then?

That is NOT the point and I cannot measure it since all devices are
RAID5. 

>> I should have stressed that reading from the ext3 is limited to 51
>> MB/s. 
> 
> Measured how?  It isn't unusualy to have less speed from the
> filesystem than the raw device.  There is some overhead after
> all, and you are seeking around.  dd is sequential which is
> optimal for performance.

Now you could have read that from my mail :)
dd if=/some-large-file of=/dev/zero
reports 50 MB/s for all large ISO files I have tested it with (more than
5, I know what I am doing), and they are not fragmented, I have sorted
the  fragmented ones out, they even do less speed. 

dd if=/dev/md1 of=/dev/zero
reports 100 MB/s, tested with several seek offsets.

Now it should be very clear to you that the filesystem creates a 50%
overhead which is inacceptable for a 2800 MHz system. And please read
my mail again where it is explained that partman probably did not use
the "stride" option which might be _the_ reason for this overhead. Even
if you don't accept/understand my problem this still should be fixed as
the RAID5 HOWTO clearly states.    

Please forward this mail to the bug-report mailinglist where you wrote to!
I only receive mails from there and cannot write to it and I don't want my
bug report to be disregarded because of misunderstandings!  
My disks are full and I need to fix the problem with the fileserver
filesystem before it gets so full that I have no space for reformatting ;)  

Thanks, Leo Bogert