# Installing Gentoo in RAID, how? [ASUS P4P800 SE]

## mariourk

I have a brand new server here. The motherboard is ASUS P4P800 SE

This thing has a on-board RAID-controller (the manual says it's a Intel ICH5R

chip)  that supports RAID-0 and RAID-1.

The idea was to configure the 2 SATA drives as RAID-1 and install Gentoo

on that RAID-volume.

I created a new RAID-1 volume with the tool during the first boot (by pressing

ctrl+i) So the RAID is configured properly. My problem is that I can't get the livecd to

recognise any RAID volume. It does see /dev/sda and /dev/sdb but no RAID.   :Crying or Very sad: 

I tried to boot with doatariad but that didn't make any difference.

Does someone know I can install Gentoo on this RAID-volume?   :Confused: 

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## cybrjackle

From my experience with raids on linux an on-board to the mobo, Linux doesn't see it the same way windows does.  Even though it is on your mobo, it isn't a "true" hardware raid so you will need to look at installing it via a software raid.

https://forums.gentoo.org/viewtopic.php?t=68706&highlight=raid

http://www.tldp.org/HOWTO/Software-RAID-HOWTO.html

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## mariourk

Wow, this is very interresting stuff.

Thanks a lot!   :Very Happy: 

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## cybrjackle

Your welcome.

Another one to look at:

https://forums.gentoo.org/viewtopic.php?t=8813&highlight=software+raid

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## Gentii

I don't know if it's explained in these howtos, but you must not use the raid tool (its indeed for windows only). You have to create your raid with linux tools, like mdadm.

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## gustafson

Very interesting to read that linux doesn't handle the on-mobo raid, and that software raid has to be used anyway.  Disappointing, particularly since I was just specing out a new system and had planned on using an on-board raid setup with SATA drives.      :Sad: 

So the question becomes why not?  Why can windows use the mobo-raid controller and not linux?  Do you know if anybody is working on it?

Also, how much degredation to performance between hardware and software raid?

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## mariourk

 *Quote:*   

> Very interesting to read that linux doesn't handle the on-mobo raid, and that software raid has to be used anyway. Disappointing,

 

Maybe, but at least there is a good alternative. And it turns out to work pretty easy    :Smile: 

 *Quote:*   

> particularly since I was just specing out a new system and had planned on using an on-board raid setup with SATA drives.

 

Well, the good news is that you can buy a cheaper mobo without a on-board RAID-controller to have RAID   :Wink: 

 *Quote:*   

> So the question becomes why not? Why can windows use the mobo-raid controller and not linux?

 

Because most (if not all....   :Confused:  ) hardware manifacturers give windows support only   :Sad: 

 *Quote:*   

> Do you know if anybody is working on it? 

 

No, not that I know of. I searched for it but didn't find anything. I also mailed my problem to ASUS but they didn't respond yet.

 *Quote:*   

> Also, how much degredation to performance between hardware and software raid?

 

I think it is not much. In fact, I think there is no difference at all. I agree with cybrjackle that the on-board RAID-controller is not really hardware-RAID but still software-RAID.

The software RAID that Linux provides can do much more than most on-board stuff

I followed the howto's cybrjackle posted and created several software-RAID volumes.

It works really easy and it is (as far as I know) reliable.

Right now I'm running a emerge system  :Very Happy: 

Thanks again cybrjackle   :Very Happy: 

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## cybrjackle

Keep in mind, that the "on-board" raid on these mobo's that "windows" can use is nothing more than a software raid, your not gaining anything other that that.

For true "hardware raid" you have to buy the real hardware, thus costing more money!   :Wink: 

I have software raid setup with 2 sata drives and I can unplug either one (shutdown) bring it back up and it works.  So as long as I just loose a drive and not a sata controller i'm good to go.  

The one thing I do wonder however is if I can put my drives on my other two sata connections on the mobo and if it will come up.  If that works (i need to try) that I have some what of a redundunadant controller.  I'm not sure if it will work that way since they use diff modules and address.

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## mariourk

How do I make my RAID bootable?

I have 2 SATA disk partitionised as followed:

md0 = /dev/sda1 + /dev/sdb1 ( 50 MB, /boot )

md1 = /dev/sda2 + /dev/sdb2 (20GB, / )

I'm not sure what to do with /etc/lilo.conf   :Confused: 

```

boot=/dev/sda #(that doesn't work, boot=/dev/md0 doesn't work either)

prompt

timeout=30

default=Gentoo

image=/boot/2.6.10

label=Gentoo

read-only

root=/dev/md1

```

And here is my /etc/fstab

```

/dev/md0  /boot  ext2  noauto,noatime 1 1

/dev/md1  /         ext3  noatime   0 0

*and some more stuff*

```

When I do #lilo, I get the following error:

```

Fatal: Unable to open /dev/md/0

```

Can anyone help me here?   :Confused: 

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## cybrjackle

Well, I don't use LILO so I can't help you there but I could tell you how grub should work if you want to switch boot loaders:

http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=1&chap=10#doc_chap2

```
grub

> device (hd0) /dev/sda

> root (hd0,0)

> setup (hd0)

```

That should work for you.

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## mariourk

Ok, I installed Grub (for the very first time...   :Rolling Eyes:  ) and that works fine.   :Very Happy: 

Here is the anwers from ASUS:

 *Quote:*   

> 
> 
> We are sorry to tell that ASUS doesn't offer any linux support. Therefore we cannot offer
> 
> any solution to solve your problem. We suggest to look on the Linux-forums
> ...

 

It's a real shame   :Crying or Very sad: 

Fortunately the Linux-forums did have an excellent solution   :Wink: 

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## cybrjackle

 :Laughing:    @ asus

Glad it works for you!

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## mariourk

I'm still unsure about one thing, what do I do if 1 disk crashes?

I have 3 partitions on both disks. The first partitions make /dev/md0, the second partitions

make /dev/md1 and the thirdh partitions make /dev/md2.

If one disk crashes, do I have to partiton the new disk before I replace the faulty disk?

Do I have to  raidhotadd per /dev/mdx ? In my case (if /dev/sda crashes)

```

raidhotadd /dev/md0 /dev/sda

raidhotadd /dev/md1 /dev/sda

raidhotadd /dev/md2 /dev/sda

```

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