Re: booting RAID partitions

Jeff Garzik (jgarzik@pobox.com)
Tue, 25 Aug 1998 17:07:34 -0400 (EDT)


Rob Hagopian wrote:
> [booting] RAID 1 shouldn't be too hard, if the first device doesn't work,
> just look
> for the same kernel (same location) on the second/third/nth drive. RAID
> 0/4/5 are a bit tougher since you actually have to get the stripes from
> each drive to assemble the kernel in memory. And that doesn't even include
> having to recreate stripes if there's a drive failure... ugg...

Not sure if you were following my logic completely; MILO would actually
contain the md driver, just as it contains almost-verbatim copies
of several other Linux kernel drivers. The drive info md needs for
booting would be passed on the kernel command line.

Without flashROM and MILO, booting RAID becomes a lot more difficult. :)

Re-creating stripes does look nasty, though :) I am looking at the
RAID patches now... (and wondering if md RAID5 can beat Solaris ODS)

Jeff

> On Tue, 25 Aug 1998, Jeff Garzik wrote:
>
> > Rob Hagopian wrote:
> > > Yes, lilo can't read the kernel from more than one drive, but that's not
> > > the issue. The problem was getting your root drive to be RAID, since you
> > > needed /sbin/mdadd, /sbin/mdrun, /etc/mdtab, and possibly /sbin/ckraid to
> > > make the RAID devices. Some of these were integrated into the kernel for
> > > RAID 0/1 by passing kernel parameters, now it can be done for all RAID
> > > devices.
> > > Yes, you'll still need to put your kernels on a floppy or something.
> >
> > Being a lucky Alpha owner, I can add RAID1/5 boot support to MILO
> > (hopefully!), which I can then blow into flashROM. Excellent solution
> > for booting my future RAID1 system partition.
> >
> > Thanks for everything (especially the links in the other msg). This
> > gives me something new to play with... :)
> >
> > Jeff

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