LSI MegaRAID program not detecting controller on Ubuntu + SC440

[Alex Jurkiewicz]

Hi All,
We have a Dell SC440 box here (purchased earlier this year) which has an 
LSI SAS RAID card in it. It has two 250gb SATA drives plugged in, 
currently setup as RAID 1.

We have FreeBSD 6 installed on this system which is working fine so far, 
but unfortunately the controller doesn't enable the write cache for the 
drives automatically -- which causes io performance to really suck!

It's apparently possible to permanently enable the write cache from 
Linux with the "MegaCli" tool from LSI. This is what I'm trying to do 
with an Ubuntu LiveCD. Sadly the documentation for this tool is 
non-existant and all I have is the output from "./MegaCli -help". A few 
Google's haven't pulled up much more helpful documentation either.

I grabbed MegaCli from the LSI website, the version is 2.00.12-1 and it 
was packaged in an rpm.

I (apparently) should be able to see a whole dump of output with the 
command "MegaCli -AdpAllInfo -aALL", sadly I get nothing but "Exit Code: 
0x00". This suggests to me the MegaCli binary can't detect the 
controller. I straced the process and it seems to fail quite early in:
[...]
read(3, "Character Devices:\n   1 mem\n   2 p"..., 1024) = 419
read(3, "", 1024) = 0
close(3) = 0
munmap(0xb8078000,4096)
ioctl(-1, MTRRIOC_SET_ENTRY, 0x99e3f78) = -1 EBADF (Bad file descriptor)
[...]

I've checked dmesg, the Virtual Disk shows up as sg3, and the sg driver 
shows up under "Character Devices" in /proc/devices.

Can anyone suggest what's going on here? Unfortunately I don't have much 
further clue about what's going on here.

Cheers,
Alex Jurkiewicz

PS: if anyone can give me the commandline to enable write cache I'd 
appreciate that too.