[BlueOnyx:01352] Re: RAID

[Michael Stauber]

Hi Tony,

> I have checked the card I have and I am pretty sure its a hardware raid.  
> I have used many raid cards and they all require drivers, for windows,
> novell and nix.  Either the driver is built in with the os, or I have
> always had to load the drivers.  Same with the good old SCSI stuff I used
> in days past. 

The problem with the LSI Megaraid is that LSI really went "cheap ass" there. 
Yes, of course you usually need drivers in order for the OS to use certain 
hardware like disk controllers. Linux typically handles this through kernel 
modules. Usually those drivers just tell the kernel how to "talk" to certain 
pieces of hardware. Like "Hey, if you want to use the HDs I have attached, 
just use those commands here." So the drivers just act as "translators" that 
allow the OS and the controller to "talk to each others".

What LSI did here was to offload some of the logic that's normally included in 
the hardware of the controller *into* the drivers. So the hardware in their 
disk controller is dumb like a doorknob and totally simplicistic. The *real* 
work has to be done by the driver and the CPU of the host system. That allows 
them to offer a controller to motherboard makers that costs like 10x less 
(hardware wise), but at the expense of extra load on the host system and less 
cross platform support as the drivers are now much more important.

Remember the "Winmodem" devices? Same story. Under Linux you were screwed if 
you had one of those.

I once did run into the LSI MegaRaid controller on an Intel SR1530HSH/SH 
server chassis. I basically had the same issues as you've encountered:

If you attempted to install any Linux on this server, chances were that it 
either would not find any disk drives. Or it found the disks, but the 
installed OS didn't boot after installation. That somewhat depended on the 
Linux you tried, or on the configuration of the LSI controller (set to 
hardware RAID or no RAID, meaning you'd use software RAID or no RAID during 
setup).

I spent several days on that issue and eventually devised a procedure that 
allowd to install Aventurin{e}:

http://www.solarspeed.net/otrs/public.pl?Action=PublicFAQ&CategoryID=2&ItemID=43

But all in all it's NOT worth the hassles. Because the available Linux drivers 
from LSI only work for certain Linux distributions and ONLY in the stock 
kernel. So during the next major YUM update which includes a new kernel your 
system may end up dead in the water after the next reboot, as the driver is 
now gone again or no longer works with the newer kernel.

Save you some grief there and get a motherboard that has a "real" controller 
that's supported by Linux, or invest some extra bucks into in an add on card 
with a real controller.

Pretty much anything from Adaptec ought to work under Linux - straight out of 
the box. I've also used the "3Ware 9650SE-2LP 2-Port SATA-2" with BlueOnyx and 
Aventurin{e}. The four port variant of it should also work just fine.

The benefit of using a "real" SATA controller is of course also that you can 
use real hardware RAID and not the crippled variants that some of the onboard 
SATA chip makers often offer.

> Also, the bx install forces a raid 1, which also useless.  (imho)

Why is RAID1 useless? It's probably the most used RAID level for good reasons.

-- 
With best regards

Michael Stauber