Booting order / SATA onboard / IDE card

[Lennart Sorensen]

On Fri, May 14, 2010 at 02:05:20PM -0400, William Park wrote:
> On Fri, May 14, 2010 at 01:28:06PM -0400, Lennart Sorensen wrote:
> > Why would anyone not raid everything?  Do you like wasting half a day
> > reinstalling the OS when the drive fails?  Sure you didn't loose your
> > data because it was on raid, but you lost access to your data, which is
> > almost as bad.
> > 
> > People who think swap and the OS don't need to be on raid when the data
> > is are just amazingly stupid.  If the machine crashses in the middle of
> > an access, it doesn't matter that your data is on raid, you can still
> > screw it up.
> > 
> > You put it all on raid or you don't bother.
> 
> How do you put OS partition on a raid?
> 
> Don't you have to use either hardware raid card or builtin chipset on
> motherboard?  If so, how do you move your disks to another computer, if
> your raid card or motherboard dies?

Well given I just installed one today, it is rather trivial.  The debian
installer certainly had no problem with it.

You simply use software raid1.  Grub2 can boot that just fine.  When it
asks where to install grub, tell it the MBR of both sda and sdb.
Now either disk can be the boot drive.

So in this case I set it up as:

sda1 50GB + sdb1 50GB software raid1 for root (md0)
sda2 200GB + sdb2 200GB software raid1 for lvm (md1)

I then created a volume group and crated a logical volume for swap,
/home and /data in the lvm.

Grub2 got installed to sda and sdb and everything just works.

Trivial really.

I can put these drives in any other PC and it will still boot and still
have raid.  I have done it this way for close to 10 years.  It has always
been possible, although in the past you had to manually take care of
installing the bootloader to both drives.

-- 
Len Sorensen
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