RAID

[Anders Karlsson]

On 1/4/06, Scott <angrykeyboarder at angrykeyboarder.com> wrote:
> Anders Karlsson wrote:
> > If you have proper on-board (hardware) RAID, you should only see one
> > disk in the installer, the logical disk.
>
> Depending on who you talk to "on-board (hardware) RAID" isn't
> necessarily "proper" and some consider it "fake".  I have no idea how
> this is determined.

I'd say that if you require userspace tools (i.e. dmraid) to even see
the arrays, then you have a fakeraid controller.

>   > If it is fake RAID, you are
> > better off setting up a MD device while installing, and when you get
> > to the partitioner, create the partitions you want (across both disks,
> > keeping the RAID candidate partitions same size or as close to as
> > possible) and change the type of the ones you need to raid or md
> > candidate, go in to the sub menu software raid (should be near top,
> > quite obvious) in the partitioner and set up your RAID relationships.
> > After that, use the mdX device(s) as you would a normal disk.
> >
>
> What is a "MD device" and will this scenario allow me to a:
>
> Configure my array as RAID0

MD stands for Multiple Devices, it is Linux software RAID. So the
answer is yes, you can have a RAID0 array, but I don't thing you can
boot a RAID0 MD unit. You could partition the disk to have a small
root partition (0.5 - 2 GB) which you mirror, then the rest you could
have as a RAID0 for all else.

> Dual/Triple/Quad-boot with other Operating Systems (including but not
> limited to, Windows XP).

Ah. Get a proper RAID card, they are about 200 dollar. Or investigate dmraid.

> I started off trying to do the dual-boot thing, but it's a no-go.
> Ubuntu (and Debian and Fedora as well) won't recognize the RAID.  It
> comes up as my just having two separate drives (which I do of course,
> but they should be showing up as RAID.

You are missing dmraid. Install that and you should see the array. I
am amazed that you even could get Ubuntu installed if you decided to
RAID0 the disks. Admittedly, I never went for the RAID0 option on my
siimage card (I value my system a bit more than that), but the Ubuntu
installer ignored the mirror setup I had on the card, so I just
disabled the 'RAID' on the card and use it as a PCI IDE card.

Sounds like you found yourself a fakeraid card mate. My sincere condoleances.

> Depending on who I talk to I either do or do not have "fake
> RAID/fakeraid".    Do SATA drives connected to a SATA RAID controller
> automatically equal "fakeraid"?

It's a fakeraid alright. A proper raid card would only show you the
logical device (i.e. the array) so Windows, Linux, OS2, *BSD would
never know what type array (0, 1, 5, 6 or 10) it really was. Once the
OS can see the physical disks of the array, it is a fakeraid
controller.

> I have two 250 GB SATA drives connected to a Promise FastTrack 378 RAID
> controller.  This and an onboard VIA VT6420 RAID are connected to and
> came with my ASUS A8V-Deluxe Motherboard ( VIA K8T800 chipset).

Nice motherboard. :)

> Someone recently told me I might have better luck connecting the drives
> to the VIA controller instead (it's unused).  I'm going to be trying
> that soon (well I'll be paying someone to switch it for me, actually).

IIRC, they are both fakeraid. You'd still need dmraid to see the array
in Linux and you'd still need to install a driver in Windows to see
the array properly.

> Presently I've got Ubuntu occupying parts of both drives with on other
> OS installed. This is a temporary situation, just so I can have
> something going. It is by no means what I want in the long term.

You have my sympathy. If I were in your shoes, I'd forget about the
RAID (do you actually really _need_ it? if you are contemplating
RAID0, you don't really care about your install that much, right?) and
stick one OS on one disk and the other OS on the other disk.

> My efforts to get the drives switched to the VIA controller could still
> be in vain, but we'll see.     Between this and the problems I'm having
> connecting my new printers, printers I bought based on their supposed
> excellent Linux compatibility -
> http://lists.ubuntu.com/archives/ubuntu-users/2006-January/062413.html
> ANYONE?? -), Winblows is looking awfully good right now....

There is a website that lists printers compatibility with Linux, I
can't remember it OTTOMH, when I do, I'll post it. If you have CUPS
installed, you should be able to just install the PPD from the media
that came with the printer and you should be able to drive it with all
features.

HTH,

--
Anders Karlsson <trudheim at gmail.com>