Re: I/O issues, iowait problems, 2.4 v 2.6

[Andrew Morton <akpm@osdl.org>]

Paul Venezia <pvenezia@jpj.net> wrote:
>
> On Mon, 2003-11-10 at 23:54, Andrew Morton wrote:
> 
>  > OK, the IO rates are obviously very poor, and the context switch rate is
>  > suspicious as well.  Certainly, testing with the single disk would help.
> 
>  I pulled the secondary, reconfigured to single drives and rebooted. All
>  is now well, performance is right where it should be.
> 
> 
>   0  0      0 1475924   7052  42384    0    0     0     0 1015     6
>   0  0      0 1475284   7076  42360    0    0     0   156 1041   311
>   0  0      0 1475284   7076  42360    0    0     0     0 1016    12
>   0  0      0 1475284   7076  42360    0    0     0     0 1026    30
>   2  0      0 1252628   7300 258852    0    0     8 37240 1157   119
>   0  3      0 1027284   7524 478064    0    0     8 66016 1441   317
>   1  3      0 818132   7728 682948    0    0     4 70752 1439   202 
>   1  3      0 593236   7944 901760    0    0     4 64576 1452    92 
>   0  4      0 531412   8008 961876    0    0     4 63680 1434    97 

OK, so either we broke the driver or there is some tuning sensitivity.

Could you please do:

	mkdir /sys
	mount none /sys -t sysfs
	cd /sys/block/sdXX/queue
	echo 512 > nr_requests

and retry the RAID setup?

Beyond that, dunno.  We'll need to hunt down the people who worked on that
driver.