I have been trying for a few days to install CentOS 5.4 on an IBM x306 and I cannot get it to properly handle the Adaptec Embedded SATA HostRAID Controller. I have been working with Linux for a few years, but this is new territory for me. I typically use Debian-based distros, but I did some research on the IBM site and found out that RHEL is a supported OS for this machine. So, I decided to give Cent a try. I have some experience with Fedora, so it's not totally foreign to me.

Anyway, I'm a bit confused. Using the IBM RAID utility, I set up a mirrored pair of 1GB SATA HDDs. When I run the Cent installer, it sees the pair as a single array. I am able to partition the array and complete the install, but when I boot into the OS, it sees the drives as 2 separate devices, sda and sdb. I can pull either one of the drives and boot with a single disk, but it doesn't seem to behave as a mirrored pair. If I make changes on sda, they are not replicated to sdb. Also, I can't use the cli or GParted to format the existing space on the array. I get an error either way. I believe this is because Cent doesn't have a driver for the RAID controller, but I don't see why it would work in the installer, but not the installed OS.

My next approach was to start over and attempt to run "linux dd" at the start of the installation. I tried to find the driver for the controller on the IBM site so I could load it when prompted, but couldn't find a newer version than RHEL 4 Update 3 (I'm assuming this would coordinate with CentOS 4.3). I tried it anyway, but when I select the floppy during the setup, it tells me it's not for this version of CentOS. I read several times that there are .img files that might help me in the 'Images' directory of disk one, but I only see diskboot.img, minstg2.img, and stage2.img. I don't think any of these are what I'm looking for. I thought there was supposed to be a drvblock.img or driverdisk.img.

At this point, I'm at total loss. I have done multiple searches in Google and been all through the IBM documentation, but without success. Could anyone help me out?

Is that Adaptec RAID controller true hardware RAID controller or just cheap one called "fake RAID"? True hardware ones should cost about $300.

If it is a "fake RAID" one, then disable it and use Linux software RAID, you will get much better safety and performance. There was a bug/change from 2.6.18-128.x to 2.6.18-164.x kernel version (I think it was then) that brakes fake RAID visibility and shows them as 2 HDD-s. I had the same problem when upgrading from earlier CentOS 5.x on nVidia's fake RAID controller.

Thanks for your response. I also got some feedback from the CentOS forums and it turns out it is fake RAID. I didn't buy the controller separately. It came with the IBM server I inherited from my old job. I had configured Windows the this series before and since I was providing drivers and it had its own interface accessible during POST, I always assumed it was a hardware RAID solution. It's actually just a software solution integrated into the firmware of the device as explained here:

http://ask.adaptec.com/scripts/adapt...?p_faqid=13298

I did go with the native Linux software RAID and so far, so good.

Native Linux RAID is excelent. It's one of main reasons I went 95% Linux on both Desktop, Laptop and server machines. Only application needed on Windows is Business Electronic Banking software. Won't run on wine.

You can play around with native RAID and create mirrors and stripes from separate partitions, like first partition on first disk mirrored with third partition on second disk, or add larger disk and use just the size of the smaller HDD for RAID and the rest as regular partition without RAID. And you can change setups while system is online.