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Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?

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Old 06-11-2008, 02:15 PM   #1
ajith_kgs
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AMD SB700 RAID not working


Hi guys..

It seems that my RAID 0 setup(with AMD SB700) isn't being detected by some of the linux distros (ubuntu 8.04 , ubuntu 8.04 alternate installer, fedora 9, linux mint 5, dreamlinux, gOS)..

The RAID setup works flawlessly well in windows. But while installing linux, it doesn't seem to get detected (my harddrives are shown seperately as /dev/sda and /dev/sdb).. Could it be a hardware fault? Did anybody try a RAID 0 setup with SB700? if so pls help me.. I am pretty confident I am doing the RAID setup procedures correctly.. does linux require any special procedures before installation?

My config is as follows..

AMD X2 4800+
Gigabyte GA-MA78GM-S2H
2GB RAM
2 x 250GB Seagate Baracuda HDD

Thank you in advance..
 
Old 06-15-2008, 12:04 AM   #2
snowtigger
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It is unfortunate that manufacture of equipment can get away with stuff like this.

However, lets point you in the right direction.

Nearly all of these motherboards and the cheap controller cards that say they have RAID on aren't telling people the whole truth. Yes you do have RAID, but it is not "true" RAID.

What is "true" RAID. Well it is RAID that is implemented in the hardware and the hardware alone. ie, you plug it all in the system, somehow get in to the config (normally you well see a prompt during initial booting). You define the RAID array and then carry on booting. Any OS will then see it as you defined the array.

What you have is known by a few names, Adaptec call it Hostraid (something like that). Others call if Softraid, Fakeraid, amongst other names. In this method you will often configure an array in the same way as above, but here is the catch, the OS needs a special driver to be able to see the array. So unless you have a kernel with the relevant code built in you will only see the individual disks of the array.

Now some of these manufactures who sell this fake raid have kindly released the information on how to speak to the array, others have not. I'm not sure if your setup is supported, but i'm sure someone on here will be able to tell you.


Last edited by snowtigger; 06-15-2008 at 12:05 AM. Reason: spelling
 
Old 06-16-2008, 02:10 AM   #3
ajith_kgs
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Thank you..

Yes I was quite confused regarding what TRUE RAID is and what I have.. I searched around in google and saw many posts that said that the support for SB700 was added from version 2.6.24 of the Linux Kernel. But I am not sure if they meant "RAID" support as well.

Anyways, I'll search around for some more time.
 
Old 06-16-2008, 02:59 AM   #4
lazlow
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There is a further catch. On most of the fakeraid setups that people have been able to get running, it is only compatible with linux not windows. So you can have raid on linux or raid on windows, but usually not both (with fakeraid).
 
Old 06-17-2008, 11:18 AM   #5
ajith_kgs
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well, my work mostly stays within Linux, I rarely look at Windows.. except for the times when i get bit by the gaming bug

I currently installed Ubuntu 8.04 LTS using software RAID.. i cudnt wait ard for finding a solution.. Since Suse has been in close partnership with AMD, i hope the Suse is going to have better support for this chip.. i'll try wen it comes out..
 
Old 06-17-2008, 01:10 PM   #6
Electro
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The reason why Windows or DOS sees the array as one drive is because it handles disk IO through the BIOS. Your software RAID controller will work OK in DOS or Windows but in Linux it will not because it does not handle disk IO through the BIOS. In Linux, you will need a device mapper or dmraid to handle software RAID. Linux will see the separate drives and the software RAID disk after running dmraid. I do not recommend using software RAID from the controller because it will not be reliable. To ease setup between Windows and Linux, I suggest spend the money on a hardware RAID controller like from 3ware.
 
Old 06-18-2008, 04:00 AM   #7
ajith_kgs
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ok. so which all company's RAID cards are supported in linux? Can you point me to a good one?, which has been tried and tested in linux..
 
Old 06-19-2008, 12:59 AM   #8
Electro
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I guess you do not understand. There are two types of RAID cards. One is software RAID, the ATI RAID for example. The other is hardware RAID such as from 3ware or Areca. A hardware RAID contains parts of a computer, but are all on an expansion board that contains software that is run independently from the main processor of the computer. The RAID array on an hardware RAID shows as one drive to the computer. Software RAID controllers are just original storage controllers with out any brains. They may include RAID software in its BIOS that is copied to main memory of the computer. The computer runs this software to handle RAID tasks. Linux is designed differently, so this RAID software that came from the software RAID controller is not used because it is high level. Linux works at the low level of the computer. In order to tell Linux to use high level commands for the software RAID controller, you will need to run dmraid.

There are two things that are needed to use the RAID array on a software RAID controller to work in Linux. One is the module or driver for the controller which you have. The other is using the utility named dmraid. This utility will initialize the device node that is for the RAID array by using a device mapper. This device mapper acts like a wrapper to use the high level code that the software RAID is running at. The reliability of using RAID from a software RAID controller is not that good although I have not tried it.

To ease Linux installation with RAID and be able to use controller with Windows, I recommend picking a model at either 3ware or Areca. 3ware is supported better for both OS.

If you insist of using software RAID from the controller, you may want to take a look at the mess you will have to do to boot up in Linux.

http://www.linuxquestions.org/linux/...D_using_dmraid
 
Old 06-20-2008, 04:49 AM   #9
ajith_kgs
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Yes, I got that point. I know now, that what I have is not a true RAID solution. I am looking at buying a Hardware RAID Card, like the one you mentioned. Right now, I am using the sofware RAID that we can setup during installation of the linux.

Thank you for the time
 
  


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