Mailinglist Archive: opensuse (2391 mails)

["Brian K. White" <brian@xxxxxxxxx>]

----- Original Message ----- 
From: "Per Jessen" <per@xxxxxxxxxxxx>
To: <opensuse@xxxxxxxxxxxx>
Sent: Friday, May 09, 2008 1:13 PM
Subject: Re: [opensuse] Suse 10.3 install - oh dear


John wrote:

> > > How do you define "unraid" ?  You probably didn't change the
> > > partition types.
> > I split the discs and reset the bios to none raid etc. 

> When you said "fake RAID" I took it to mean "Linux MD RAID"

Why would you think that? Google fake raid.

It means the type of raid that is neither purely software nor purely hardware.
It's when the bios of a motherboard or firmware of a drive controller (same 
thing) povides just enough hooks for a boot loader or kernel that knows how to 
use that particular fake-raid controller to get started booting. It does not 
actually perform any raid work though, the real work is all done in software 
similarly to "linux md raid" except it usually has to take place right within 
in a drive controller driver, not as a seperate layer on top of any drive 
conroller driver the way md raid works.

It's called fakeraid because the box simply says it's a raid controller, same 
as real raid cards, yet it performs almost no raid functions itself.

FreeBSD has support for some controllers that do this, And linux did for a 
while in 2.4, but it was dropped in 2.6
The recommendation is to always disable the raid feature in any fake-raid 
controllers and use the controller as a plain controller, and do any raid using 
md raid.

You lose a few hardware-raid capabilitis and features that way, such as having 
the raid present one virtual disk which can have partitions and mbr within the 
raid volume, and booting directly from a raid 0/10/5/50 etc..

But the benefits are
* kernel developers don't waste time duplicating effort in multile places (md 
raid, plus in various fakeraid drivers)
* you don't get stuck trying to use a buggy raid driver that wasn't implimented 
as well as some other driver or isn't being maintained as well.
* md raid components can be assembled and used any where any time on any kind 
of drive, any kind of controller, any kind of driver, after any kind of backup 
or imaging backup & recovery. You don't need the original controller or driver 
or even the type of drive in order to access data saved from failed hardware.

-- 
Brian K. White    brian@xxxxxxxxx    http://www.myspace.com/KEYofR
+++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++.
filePro  BBx    Linux  SCO  FreeBSD    #callahans  Satriani  Filk!

--
To unsubscribe, e-mail: opensuse+unsubscribe@xxxxxxxxxxxx
For additional commands, e-mail: opensuse+help@xxxxxxxxxxxx