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Old 01-02-06, 01:28 AM   #5
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Join Date: Jan 2005
Posts: 135
Default Re: Dual Booting With Linux in Raid

According to nVidia, who can certainly chirp-in here if they want, there are no installable drivers for Linux because direct support for NV RAID has been in the kernel for "quite some time" which means, IIRC, kernels greater than 2.6.9-12. ANY distro using ANY kernel version less than that has NO support whatsoever for what I have renamed HARM(see sig).

IF the Linux distribution uses a recent version of the Linux kernel, e.g., 2.6.9-22, it can support the HARM via dmraid (not md as most RAIDs use) for the RAID modes that Linux can support: 0, 1, 5 & 10(I don't know about the JBOD...).
The level of that support is a complete unknown as NVIDIA has not published any document that I can find which describes how the RAID support works in Linux. HARM is a FAKE RAID but because NVIDIA HIDES THAT FACT, it is unknown how much they do or do not do to assist Microsoft OS in running RAID 0, 1, 1+0, JBOD or on some *new* mobos the RAID 5. RAID 5 support was only recently added; older mobos with the nForce platform might get support through BIOS upgrade or might not. ASK nVidia or the mobo manf. directly about that. At best, I think the HARM performs parity calculations on the chipset, thereby offloading some of the more CPU intensive memory work. Whether that is of any real life benefit is also UNKNOWN because there are NO independent tests that I have seen to indicate that using the HARM as a HW+SW RAID actually increases quality(i.e., accurate & safe) throughput which is the real bottom line.

However, the problem you have described, as best as I could determine from what you wrote, is a matter of the distribution supporting dmraid (and thereby HARM) during the install. NONE do that with the possible exception of Gentoo and it is only mentioned because nobody seems to know whether one can get support for dmraid during install of Gentoo or not but there is a web page claiming it can be done with the instructions on that page. I have never tried it nor do I know of anyone who has ever claimed to have done it other than the author of that article, of course. I am sure s/he would enjoy feedback about the success/failure from anyone attempting it.

The problem boils down to support of dmraid during the install of the distribution. Mandrakelinux was working on that last year but I have no idea if the renamed company, Mandriva, continued that effort. The reason that dmraid is needed is that it supports what is known as "foreign" RAID, i.e., HW RAIDs as well as the SW RAIDs that are used by various companies. The md driver cannot do that. The md driver is what virtually all distributions use to setup and manage RAID on the distro for many years. Linux SW RAID has been around for quite a while... however the dmraid support is, in comparison to md, relatively new.
The support for dmraid requires changes to the wya the boot process is done. The is not so easy to implement but can be done. At this time, the best we can do is to test what is available so that it can be implemented universally in a streamlined manner. Sometime back (>1yr) I did see a post that someone was working on the implemenatation for Fedora also. idunno what happened on it...

I don't have the link handy but if you search this forum there is a link here for the web page describing how Gentoo gets support for dmraid during the install. Of course Google should work too ...
You can check at Man* cooker or in the Bugzilla for the dmraid support status by them. The only Debian that *might* have support would be the *buntu Deb's(Ubuntu or Kubuntu) because they use relatively recent kernels. MY personal experience indicates they do not. CentOS 4.2, which is ~ RHEL 4.2, might but I did not see it. I could report on that but while trying to get the MS support working, my mobo somewhat mysteriously died: It failed to POST after a shutdown.
I have no idea what caused it. I won't have a new one from RMA until next week...

Based upon the last couple of weeks, I would say that you will get ZERO support from nVidia on this subject. Perhaps that was because of the holidays but upon reading other much too brief replies to "Platform" problems, I think not. I think it is general nVidia standard policy to provide the shaft to Linux users as much as possible by obfuscation and ignorance. You will have better luck/answers from other non-nv forums, especially those designated for md and dmraid support.

If my mobo continues to have problems I will be exchanging it for a NON-NV platform and, by the Grace of God Almighty, be thankful that I got out from under the NV thumb by never buying another mobo with NV as the base chipset again. Foolish me thought that NV would have support for Linux because of their graphics support. I was even a bigger D! fool for believing that the platform was implementing a HW RAID solution which it does not.

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Last edited by fhj52; 01-02-06 at 02:07 AM.
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