# sata raid 1 - software or hardware?

## gherardo

Sorry for posting such general questions. I need to set up a mailserver,   have a low budget, and am not an expert with gentoo  (I hope the answer will not be: "give up")

In general, is it feasible to make gentoo working with software raid 1 and SATA disks ? Or is it definitely tricky?

Should I give up with the benefits of SATA and stick back to dear old IDE disks?

I am looking for some slightly "old" mobo, like asus a7v600-X with onboard raid support; what about it?

What would you recommend in general?

Thanks in advance

G.

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## Robin79

Iam not en expert but i have a ASUS-P5AD2 Deluxe card with sata and raid and it works not so much probs just needed to patch the kernel for the IDE raid.. Sata worked imidetley after i have activated it in the kernel so sata works raid works. I hope you will get an better answer from any experts  :Razz: 

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## gherardo

Thank you for the answer. Anyway I confess that I have even more stupid questions. I never set up RAID before. Browsing the net in search for documentation I got confused by the meaning of "software raid". Apparently, it can have quite different meanings:

1. a controller which is not a fully independent piece of hardware, more or less like a winmodem (i.e. parts of its job are done by software emulation).

These things usually are integrated on the mobo, and the "software part" of the raid device lives in the bios. Right? (let me call that "semisoftware raid")

2. no hardware at all, namely there are ordinary disks (possibly of different size and vendors), and RAID service is done by the kernel with no other specific hardware contribution (let me call that "truly software raid").

Is that right?

If yes , I have the following general questions 

a. Does gentoo work well with SATA + semisoftware RAID?

b) Does gentoo work well  with software SATA +truly software RAID ?

 Moreover, is it a sensible program to buy a mobo with software RAID controller (in the sense of 1 above) and

  first:         try to make SATA+  semisoftware RAID work;

  second:  if above fails, disable RAID services at BIOS level and try

                   to set up truly software  RAID service;

  third:        if above fails, kill myself?

 My candidate mobo is asus  a7v600-x (I found a bargain).

Sorry for the long and naive question.

Thank you in advance.

G.

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## NeddySeagoon

gherardo,

Most motherboard raid controllers are software. The software for windows users is provided in the BIOS and the fact they are not hardware raid controllers is glossed over.

In gentoo, you can use the kernel software raid or the BIOS software raid. The only reason for choosing the BIOS raid is to be able to dual boot with windows.

Setting up a mirrored kernel software raid system (RAID 1) in Gentoo is easy, and takes just a few additional steps.

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## gherardo

 *Quote:*   

> 
> 
> gherardo, 
> 
> Most motherboard raid controllers are software. The software for windows users is provided in the BIOS and the fact they are not hardware raid controllers is glossed over. 
> ...

 

Thank you for  concise and precise answer, and for encouragement. I promise I'll post a follow up for dummies like myself.

 Just another question: am I bound to encounter serious problems buying a mobo with bios SATA raid, disabling it at bios level, and set up kernel software raid? The reason for this question is that, apparently, all mobos with onboard SATA controller also come with  bios software raid.  

Thank you once again.

[/quote]  :Very Happy: 

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## Gherald

you'll want to disable raid in the bios

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## NeddySeagoon

gherardo,

My A7N8X Delux has a Silicon Image 3112A SATA controller that provides BIOS RAID. By default, both drives are independant. Just leave them that way.

I'm running RAID 1 for /boot, two seperate swap partitions and RAID 0 for everthing else. (Grub cannot boot from a RAID 0 volume)

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## gherardo@piacitelli.org

 *Quote:*   

> 
> 
> NeddySeagoon answered on Sun Dec 19, 2004 12:42 pm:
> 
> "My A7N8X Delux has a Silicon Image 3112A SATA controller that provides BIOS RAID. By default, both drives are independant. Just leave them that way.
> ...

 

Ok, I had some trouble and now I am back to building the server. Thank you very much if you still are listening to this thread. 

Now my problem is the following.

It is true that, if I disable the VIA RAID SATA BOOTROM (bios setup of Asus A7V880 -->  advanced --> chipset --> SouthBridge  VIA VT8237) I see two independent SATA disks; but I cannot boot any of them, they are invisible to the BIOS... If I enable the VIA RAID SATA BOOTROM I can boot from the array; I can even select which of the parallelized disks to try the first.  But that's not what I need.

Is there still any hope that I can set up a Linux kernel-software bootable RAID1 array of SATA disks? If not, are there reasonable workarounds?

Thank you very much.

Gherardo

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## NeddySeagoon

gherardo@piacitelli.org,

I keep an eye on my old posts. When a new addition is made, it pops up in my posts again.

I'm not sure what you mean by the independant disks are invisible to the BIOS, so you can't boot.

When I made my RAID 1 boot, I had to set it up degraded with only one drive in it and install grub and the kernel on the other drive as a normal install. When that worked, I installed grub on the degraded RAID volume and copied the normal /boot to the degraded RAID /boot. 

After booting the degraded raid volume, I raidhotadd ed the normal volume to the array, which destroys all the data on the normal volume.

You must install grub on each volume in the RAID 1 set since it installs in some hidden space outside of the filesystem, so this is not updated by the copy.

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## zpet731

Hi, I posted to another thread earlier but this one is more appropriate to what I need to find out.

I currently built a:

AMD64 system 3200+

GA-N8NF-9 motherboard

6600 GT graphics card

1GB RAM

2 SATA 160GB drives

Now, Im only planning to run gentoo on this system so no dual boot or anything.

I've read quite a bit on SATA raid threads, most of the threads are excellent but I still need a few things answered before I start installing gentoo on it. Im using a minimal 2005.0 image that I downloaded off the net.

Now if I am to use Raid 0 setup what is my best option do I use the motherboard raid or not? Im not sure which way is better so hopefully someone can enlighten me on this issue.

Also if I am to use the software raid and control it completely from linux do I need to disable the raid in the bios? My motherboard asks me to setup the array each time I boot up and the sata raid is enabled by default. Can someone explain what needs to be done. Thanks!!!

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## zpet731

I would also like to know which one is faster (BIOS or Kernel) and has less strain on the CPU, or is it the same?

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## makton3g

^^^--- I am wondering the same thing. That is the exact thing I want to know.

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## zpet731

 *makton3g wrote:*   

> ^^^--- I am wondering the same thing. That is the exact thing I want to know.

 

Well I have stopped wondering and I went for software raid (ie. disabling raid in the bios). There are many ups and downs for each setup and it is well argued all over the forum. In the end I  was very pleased with the result. Now my new machine is emerging software and the hard disk is working like a dream. And with speeds of around 54-58MB/s for individual hard drives literally doubled 106-112MB/s for raid 0.

Also as Linux software raid works on the partition level it gives you great flexibility on how you raid those partitions. Good luck and if you get stuck don't hesitate to post back for help.

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