[NCLUG] Magic Boot CD?

[Brian Wood]

On Sunday 31 May 2009 10:40:01 Paul Hummer wrote:
> On Fri, 29 May 2009 19:19:28 -0700 (PDT), Marcio Luis Teixeira
>
> <marciot at yahoo.com> wrote:
> > I'm half tempted to write "Do not remove, contains magic spell" on a
> > blank CD and stick it in the drive, then use it that way. It'll be like
> > my very own "magic switch" story:
>
> That story would then be posted on thedailywtf by the person who replaces
> you later down the road. :)
>
> > Seriously, has anyone seen this sort of thing before? A few details: This
> > particular box has an old 4-port 3ware IDE RAID PCI controller. Two IDE
> > HD drives are both connected to the controller. The CD-ROM drive is the
> > only thing connected to the integrated IDE controller on the mobo. The
> > only other odd thing about this system is that I was unable to get Linux
> > to boot at all with the default partitioning setup with the logical
> > volumes and such. I had to remove those and make regular partitions like
> > in the good ol' days.
>
> You should set your BIOS to boot directly to the HDD, or, in this case, the
> raid card.  That way, it doesn't scan the CD drive at all.  In order for
> the kernel to boot to LVM partitions, the kernel has to have that support
> built-in. It sounds like the drivers for your raid card (probably fakeraid)
> are already supported by your kernel.  It might be a combination of raid
> card and LVM that causes it not to boot.  My last experience with fakeraid
> has convinced my that you should go full hardware raid or settle for
> software raid.  None of this "in-between" crap.

FakeRAID really is software RAID. The only "help" most mobos give is to store 
some parameters of the array(s) to pass to the driver.

Actually all RAID is "software", the question is, where is that software 
running? In the case of Hardware RAID it's running on the RAID card. 

But the RAID card can present to the OS as a single drive, making things like 
booting easier. Software RAID can't boot from a RAID0, as an example.

Linux software RAID is really quite good these days. Minimal CPU overhead, and 
more flexibility than a lot of hardware RAID (like the ability to use 
partitions instead of entire drives).

Another problem with hardware RAID is some controllers can be picky about what 
drives they will work with, and if the controller fails you can be in trouble 
is you can't get an identical card.

-- 
beww
bwood at beww.org