Rhel 3 Ws & Via Vt8237 Sata Raid
 

. I recently purchased a MSI KM4M-V motherboard, utilizing the VIA VT8237 chip for SATA RAID1 (two Hitachi SATA 120GB drives). I am attempting to install Red Hat Enterprise Linux 3 WS (an edition purchased last year-- 2003), but cannot seem to get the installer to recognize the drives.

. I have downloaded the suggested driver package (via_raid_linux_v100_20040412.zip) and followed the instructions by copying the precompiled viamraid.img for Red Hat 9.0 to a floppy using "dd if=driverdisk/viamraid.img of=/dev/fd0"

. When I boot from the installation CD, specify "linux expert" and go through the procedure of directing anaconda to the floppy drive, I get the following error message:

"No devices of the appropriate type were found on this driver disk. Would you like to manually select the driver, continue anyway, or load another driver disk?"

. If I select "Manually choose", I do see the "Raid controller,VIA technologies. (viamraid)" option int he list. When I select "OK", I am asked for "More Driver Disks?" and I select "No." After selecting the language, keyboard layout, and then where my installation media is, I am given a warning:

"No hard drives have been found. You probably need to manually choose device ddrivers for the installation to succeed. Would you like to select drivers now?"

. I indicate yes, try to "Add Device", select the same driver, but am still given the error message:

"No device drivers have been loaded for your system. Would you like to load any now?"

. Can't get past this point. Any help would be greatly appreciated.... thanks!

OK....here's the deal with the RAID driver...

The .img file for Red Hat 9 is not going to work with Enteprise Linux 3. The driver diskette image was compiled only for certain kernels in Red Hat 9, which are based on 2.4.20-something. The kernels in Enteprise Linux 3 are 2.4.21 based. Since the installer reads the floppy and sees that there is no matching kernel available, then this is why it throws out the message that it cannot locate any of the appropriate devices. Since there's no driver available to tell the operating system about the raid array, the installer is not going to find any drives connected to the SATA controlelr.

If there is no via raid driver diskette for Red Hat Enteprise 3 then you are out of luck getting the hardware raid setup to work....here's why:

A lot of the SATA raid controllers out there (save 3Ware) are not truly hardware raid controllers. They rely either on a BIOS function of the raid controller or a separate software driver to make the raid work. If you've ever dealt with a "winmodem" this is a similar situation.

A driver from the manufacturer is required to make the Raid array visible to the operating system.
Why doesn't Red Hat supply this driver natively you ask? Becasue the drivers, most of the time, are closed-source. Red Hat, or any other distro maker, is not going to include closed-source drivers in their distribution. If there is no source code available from the manufacturer, (which it sounds like there isn't) then you won't be able to use the diskette with anything other than Red Hat 9.

Drivers like this are also written in binary format and are precompiled to work with certain kernels...if you try to use the driver disk with any kernel outside of what's on the driver disk, then the driver will not load.

If you want the installer to see your hard drives on Enterprise Linux 3 you are going to have to disable the "hardware" raid on the raid adapter and set up software raid via the operating system. Red Hat should recognize the SATA controller without the Raid enabled.

For best results, I would download the Update 3 .iso's of Red Hat Enterprise Linux 3 WS. Update 3 has a lot of expanded Serial ATA support included in it. If you've registered your product already, go to https://rhn.redhat.com and log in. From there locate the "Channels" tab and click on it. On that page will be a link called "easy isos" on the left...click that and you will be taken to a page with a list of operating systems you can download the iso's for...locate WS v.3 and click on it....download the Update 3 set of .isos....binary disks 1-4 are what you'll need.

I hope that helps!

Here's some more information on lot of those SATA cards that claim to be hardware raid...this was written by Jeff Garzik:

http://linux.yyz.us/sata/faq-sata-raid.html

http://linux.yyz.us/sata/sata-status.html

http://linux.yyz.us/sata/software-status.html

. Thanks hkb33 for the quick response!

. Sadly, I figured as much that I'd need to compile the driver myself. I had tried to, but was getting some errors, and I figured it might be quicker to use the precompiled binaries. Guess the kernels are different (like you said).

. Either way, from a theoretical standpoint, how useful are these "fake RAID" controllers (as Garzik calls them)? When we decided to go about building this File Server, we figured we'd try and jump on the redundancy bandwagon and pitch some money into RAID. We thought we found a nice situation with a fair number of motherboards supplying on-board RAID. We thought that this was a nicer solution than having everything controlled by the OS-- we had come across reports stating that hardware RAID protects data even if the OS is corrupted beyond recovery, while data is inaccessible (either in part or in its entirety) when using software RAID.

-> how protected is the data from OS corruption with a VT8237 controlled array?

. And I figure that since this is being labeled as software RAID, should we expect pretty much the same performance as an entirely OS controlled array? I presume that the hardware RAID doesn't steal as many CPU cycles.... does this fall somewhere in-between, or is it pretty much equivalent to a software implementation?

-> are there any advantages of the VT8237 "software RAID" over a Linux controlled array (or are they pretty much equivalent?)

. Finally... any good refernces for setting up RAID under Red Hat? Can't seem to find one that has a gentle enough introduction to this new "toy" of ours....

. Thanks again!

I don't know how well the data will be protected with your particular raid contorller. Hardware RAID (no matter how nice it is) will not always protect your data. If the raid array were to develop a bad block or stripe(s) on it, then you could be in for some serious damage to your data. I know this from experience supporting server hardware. My guess is that the VT8237 isn't going to protect you any better....I've never worked with that particular controller, so I can't say how good it is, although given the fact that it's not true hardware RAID I wouldn't be surprised to see it give you trouble.

In my opinion you probably aren't going to gain that much from using the SATA RAID as opposed to the Linux Software Raid performance-wise...also...if you go with the promise driver, remember that the driver is kernel-specific...if you update the kernel on the system and the driver is not compiled against that particular kernel, be prepared to see a kernel panic when booting to the new kernel.

Here's some docs from Red Hat on how to set up software RAID via the operating system

http://www.redhat.com/docs/manuals/e...titioning.html

http://www.redhat.com/docs/manuals/e...ware-raid.html