MD3000 configurations? (performance issue) going nuts!

[u1_fd at dslr.net]

Under kernel 2.6.18, as provided by RHEL5, CentOS5 or Fedora Core 5, I 
can't make
a new MD3000 perform when paired to a Dell 1950 with the provided SAS 5 HBA
card (PCI-X) and using X535 quad core cpus, etc etc.

1. Driver release numbers are all over the place.
The MD3000 resource CD invents and provides driver release 4.x for the 
LSI 1068
based controllers, but kernel versions come with 3.04.02, and Dell 
itself offers source
to "3.02.83.12-5" for rhel5/suse.

None of the source from Dell (4.x or 3.02.83.12-5) can be compiled 
against any kernel
past 2.9.18 because of the change to the workqueue API.

2. The worst problem is when the array does come up, read performance is 
awful.
hdparm -t reports 3mb/sec read, and iozone confirms it.
Running vmstat during iozone shows blocks out during write of ~100k but 
during
reads blocks in are just 3000 per second.

3. Write is mid 1xx mb/sec, which is slower than the integrated PERC 5 
on the same
machine with a simple RAID1 pair of the same 146gb sas drives.
worse, write speed does not improve with more disks. It is no faster 
with two
disks in a RAID10 LUN, as it is with all 16 disks!

I'm thinking under linux these things are lemons.
If you currently use them, can you help & reply with

uname -a
modinfo mptsas | grep version
hdparm -t on a block device that comes from a LUN
lspci | grep 1068

any other comments on speed, failover, etc, that you've observed?

I've seen other topics here that suggest the PCI-X vs PCI Express change 
may have killed things,
but even if I get read performance to mid 100s MB/sec its still very 
upsetting considering a single
chip PERC 5 that comes with every dell is doing better and scales, to 
some extent, with the spindles.

Last question, we've an unused MD1000 , does _that_ offer good linux 
performance?

thanks!!