New style raid support during install (was Re: kernel support, v0.36 v's v0.9)
I pretty confident with raid, but im still finding my way with debian boot
methods (eg dbootstrap), im not a maintainer yet.
This is how as i see it the raid2 process could work in debian
Boot from a kernel patched with raid v0.90 support, size difference?
At the partitioning stage intended raid partitions are marked as type fd
(raid autodetection) with fdisk.
Its important to make sure that the /boot partition isnt on a raid
partition or lilo will fail and the system will not boot, so it would be
good to be able to check for this.
Once the boot process gets to the stage where its located the base package
has been located the user level raidtools (from the raditools2.deb) can be
extracted, this contains 84KB of binaries. The two important binaries that
need to be run before the raid partition can be used are mkraid and
raidstart.
Once this is done the raid appears as a regular partition and the normal
install process can continue.
In summery, this is what would need to be done as i see it
- the rescue disk would have to be patched with raid v0.90 (2.5KB larger
bzImage than if no raid support)
- /dev/md? where ?=0,1,2,3 etc would have to be made (if they arent
already)
- binaries from the raidtools2.deb would nned to be in the base.tgz (84KB)
- The menu system would have to recognise /dev/md0 as a valid target
partition (if it doesnt already)
- Check /boot partition isnt on a /dev/md?
If its too late in the development cycle to implement new feature such as
root raid support then so be it, but it will be good feature to have in
there, and its something i am quite prepared to spent a lot of time on in
the coming months (although the next 3 weeks i will be distracted with uni)
Thanks
Glenn McGrath
P.S. sorry about all the typo's in original post, i should read my emails
before i post them....
Subject: Re: kernel support, v0.36 v's v0.9
> "Glenn McGrath" <Glenn.McGrath@jcu.edu.au> writes:
>
> > The current boot floppies come with the standard raid multidisk support.
> > The raidtools packages thats that "If you are creating new RAID arrays,
the
> > raidtools2 package and newer RAID drivers may be a better choice."
> > One of the features of newer raid is that the kernel can autodetect raid
> > partition on boot.
> >
> > I think raid is a really usefull but underutilised feature of linux. If
we
> > packaged
> > debian boot with raidtools2 and raidv0.9 kernel then it would lower the
> > "dificulty" barrier that stops many people using raid.
>
> Do others agree? I don't mind dropping boot-floppies compatability
> with old raids. The only downside is people trying to use
> boot-floppies as a rescue disk for an older raid system, but I'm
> willing to sacrifice that if there are significant benefits.
>
> > I understand debian likes to aim at the lowest common denominator, but
if an
> > installation already has a raid setup there more likely to do an update
from
> > there existing system rather than use boot floppies.
>
> Right, with the rescue scenario caveat listed above.
>
> > The user level raid tools have to match the version of raid support in
the
> > kernel. so its hard to support both. I dont think there is any major
size
> > difference between old and new raid support
>
> Assuming someone volunteers to work on it, I think we should move
> ahead with an experimental implementation. What changes would
> raidtools2 support require? Can we confirm it would fit?
>
> Are there things that dbootstrap should do to help RAID configuration?
> Could someone knowledgable about RAID add RAID documentation? I
> really havn't worked with Linux RAID much at all (only Solaris stuff).
>
> --
> .....Adam Di Carlo....adam@onShore.com.....<URL:http://www.onShore.com/>
>
>
> --
> To UNSUBSCRIBE, email to debian-boot-request@lists.debian.org
> with a subject of "unsubscribe". Trouble? Contact
listmaster@lists.debian.org
>
>
>
Reply to: