# Hardware RAID 1, supported by Gentoo  kernel.

## warrgoth

Pleace tell me, where can I get a list of RAID controllers which is 100% supported by Gentoo-2.6.16(or 15) kernel ?

cause when I tried to install RAID1 on server barebone with integrated AIC 7901 chip (HostRAID) - I saw that system see 4 disks, while must only 2 (2 others might be a mirrors)... I can't find any Gentoo drivers for this chip.

Can anyone advise me something?

thanks!

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## NeddySeagoon

warrgoth,

Linux raid comes in 3 types :-

Hardware Raid 

Kernel Software Raid

BIOS Software Raid 

Harware raid needs a seperate plug in card and normally a 64 bit 66MHz PCI bus to make it worth the expense.

Kernel software raid, is well tested and robust.

BIOS Software Raid, which is what you have, needs third party kernel modules in linux. Google for dmraid.

Unless you need both Windows and Linux to access the raid, you should disable the BIOS software raid and use kernel raid.

Kernel raid is also portable ... you can move the drives to new hardware when your system dies. The data format on the drives is propratry with hardware and software raid. You must have identical hardware to recover your raid data then the hardware fails.

  =========== edit =============

The Gentoo liveCD has a dmraid boot option if you really really want fakeraid.

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## warrgoth

Okey

Think, I need Hardware RAID

So if I want to set up raid without any additional drivers, to install card in my barebone. If I want to install Gentoo on server and it will see controller and work with RAID 1 correctly without any tuning

just set a card - and go! plug-n-p;ay))

what card I need? Can you give me a link to read about?

or what cards are supported?

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## chrismortimore

Adaptec make Linux compatible RAID cards, although they are a bit pricey.  Here is their site: http://www.adaptec.com/en-US/_common/br_host/

Just make sure that Linux is listed in the "Supported Operating Systems" section of the tech specs and you're good to go.

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## warrgoth

I see

but why Gentoo does not see onboard controller - it is Adaptec too?

or I need some drivers?

but there are drivers only for suse and redhat - are they compartible with gentoo?

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## chrismortimore

 *warrgoth wrote:*   

> but why Gentoo does not see onboard controller - it is Adaptec too?
> 
> or I need some drivers?

 You'll need to add support into your kernel (assuming it exists).  So yes, you need drivers basically.  Post the output of "lspci" so I can see what the chip calls itself and lets see if its supported.

 *warrgoth wrote:*   

> but there are drivers only for suse and redhat - are they compartible with gentoo?

 It will work, Linux is Linux.  The drivers will be in some kind of package though (like RPM or suchlike), but you can still use them with a little bit of work.

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## warrgoth

okay

I will post

but now one more question... (excuse for my misunderstanding of situation))

while configuring RAID through scsi utility (pre-boot) I didn't see that RAID is not build - it was only in process of building....

so I've tried to install system on not properly avaliable RAID - it was my mistake

so can it be a possible reason of system see 4 discs instead of 2 ?

maybe after full rebuilding  - when RAID 1 will ready - it will see it?

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## NeddySeagoon

warrgoth,

BIOS Raid systems like yours vary. Some hide the underlying drives from the kernel some don't

It would be possible for you to see two or six devices.

Since you have a fakeraid controller, you need to start the gentoo liveCD with 

```
gentoo dodmraid
```

 if you really want to use it.

However, kernel raid is more flexible, no slower and better tested. The only reason for using fakeraid is because Linux and Windows must share the raid.

Fakeraid also needs third party kernel modules. Be sure to 

```
emerge dmraid 
```

before you make your kernel and its initrd file.

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## martin.k

3ware makes good hardware RAID controllers for SATA and ATA 133 drives.

www.3ware.com

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## warrgoth

No

I don't wanna fakeraid  and kernel raid

I need hardware raid only

can I buy a card from Adaptec (chip is the same as intregrated) - and then install it and have no problem?

or I need other card ?

what card I must buy to have no problem with set up of hardware raid 1 ? only set it into server, configure raid and go on? If you have an experience in this - advise me how to be, pleace?

all I need - a card to set up, which is compartible with Gentoo (and, if possible, have drivers already in kernel installed)

P.S. Disks - SCSI, so I need SCSI RAID card - I didn't see any 3ware cards with SCSI RAID there (may be I have missed smth.)

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## NeddySeagoon

warrgoth,

No - you cannot buy the same chip. Its not a real raid controller.

If you buy it on an add in card, its still fakeraid and works in exactly the same way as your on board controller..

Hardware raid is costly - Its like a plug in computer for your computer. A hardware raid card contains a CPU and memory so it can do all the raid calculations that are needed and hide the raid structure from the kernel.

As martin.k says, look at 3ware for hardware raid.

Its easy to tell read and fake raid apart by the price. Real raid will be 100s UKP fakeraid 10s UKP.

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## warrgoth

3ware have no controllers for SCSI discs as I have seen

And I still want hardware RAID, although it will be a price like 300-400 USD - so be it!

In kernel docs (/usr/src/linux) - I read that Mylex cards supported, it seems that Mylex DAC960 is not a fakeraid but real hardware raid

Have you any experience with those cards?

strange that card costs lower than 200..... )

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## NeddySeagoon

warrgoth,

LSI Megaraid provides hardware raid but I have never used it.

I've seen a Linux kernel driver called Megaraid so I suppose its for these cards ?

This is not a reccomendation - I've not needed hardware raid ever and like I say, I have not used these LSI cards.

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