Install over LAN

[Liam Proven]

On 17 October 2012 21:24, Keith Clark <keithclark at waterloosubstop.com> wrote:
> N.B. what kind of RAID array is it? If it is a firmware or software RAID, it
> might not work under Ubuntu.
> --------------------------------------------------
> RAID is:
>
> ATA133 RAID supported by Promise PDC20276 controller
>
> I have a CD on hand, old as it may be.  Ubuntu 9.04.

OK - what OS is the machine running at the moment? Already Ubuntu?

In that case, it will almost certainly still work.

RAID is quite complicated. There are 3 kinds, and the problem is,
manufacturers lie about which theirs is for marketing purposes:

"Hardware RAID" means a chip and software on a card (or *very*
occasionally on an expensive, specialist motherboard) which controls
the disks for itself. This kind of RAID appears to the OS on the
computer as one big disk; the computer can't "see" the individual
drives. RAID controllers are *expensive* - as much or more as one of
the disks, as a guide.

"Software RAID" means that the OS itself combines the disks into a
RAID volume and the OS does the calculations and so on in software.
Linux has this built in. Only server versions of Windows and Mac OS X
can do it; the workstation versions cannot.

The Linux tool for managing software RAIDs is called "mdadm" and the
devices tend to be called /dev/md0, md1 and so on. (I don't know what
it stands for; I use 'multi-disk' to remember it, myself.)

"Firmware RAID" (also called "Fake RAID") is sort of in the middle. It
is basically intended for Windows users who can't use their OS's RAID
functionality for licencing reasons (i.e. the software vendor is
screwing them over). It uses special connectors on the motherboard or
controller card plus some firmware on a chip on the card or
motherboard plus a special device driver in the OS. Boot with the
firmware off or no driver installed, the OS sees the individual
drives, not the RAID volume. Boot with the firmware enabled and the
device driver loaded and the OS sees the RAID volume.

http://en.wikipedia.org/wiki/RAID#Implementations

Promise usually sell cheap, firmware RAID solutions on cheap (£10-£30
/ $15-$50) cards.

I can't find your PDC20276 on Promise's site, just various downloads
from a decade ago calling it a FastTrak TX. That's their line of cheap
desktop EIDE firmware RAID cards. I don't know this, it's just a
guess, but I'm thinking it's a cheap firmware RAID card. I have 2 or 3
such generic cards myself - they work fine as extra EIDE channels
under Linux.

You /can/ use firmware RAID under Linux using a tool called "dmraid"
(the reverse of mdraid, you see, haha). But unless you need to, don't;
the software RAID implementation is better. If you have the option,
disable or ignore the card's BIOS, ignore `dmraid` and use an `mdraid`
instead. If you use the Alternate CD to install, you can create a
mirror pair during installation, but not with the graphical LiveCD.

-- 
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