Re: install Etch with raid level 10
On Wednesday 26 September 2007 09:59, Scott Lair wrote:
> C M Reinehr wrote:
> > On Wednesday 26 September 2007 09:21, Dave Ewart wrote:
> > > On Wednesday, 26.09.2007 at 09:49 -0400, Scott Lair wrote:
> > > > I tried to install Etch on AMD64 using raid level 10. After I
> > > > partitioned the drives, I went to create the md devices and could
> > > > only choose from raid levels 0,1 or 5. Should I be able to install
> > > > with level 10? I tried the latest netinst.iso and the cdrom install
> > > > disk 1 with the same results.
> > >
> > > There is no direct support for RAID-10 via software RAID, you have to
> > > make yourself two RAID-1 arrays and then apply a second layer of
> > > software RAID-0 over the top.
> > >
> > > The installer may not support RAID-10 directly because of the
> > > multi-layer approach.
> > >
> > > Normally, one makes a RAID-10 software setup as follows:
> > >
> > > mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sd[ab]1
> > > mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sd[cd]1
> > > mdadm --create /dev/md2 --level=0 --raid-devices=2 /dev/md[01]
> > >
> > > I'd be interested to know if you can approach the installation in the
> > > same way, actually.
> > >
> > > Dave.
> >
> > That's not entirely true. Etch does support RAID-10, just not the
> > installer. What I would suggest is first to do a minimal installation to
> > a small RAID-1 partition, including GRUB to the MBR. Then, once you have
> > booted into this system, use the system tools (cfdisk, mdadm, & lvm) to
> > set up the rest of the drive(s) as RAID-10 (with or without LVM). Then,
> > do a debootstrap installation of a complete system into this. Finally,
> > your RAID-1 partition becomes your /boot partition. Not the most direct
> > route, but it works.
>
> That sounds like what I would like to do. So the original installation
> gets removed once the RAID-10 install is done correct? I'm wondering about
> the size of the initial installation partition. I generally make /boot
> about 200Meg. Do you think that would be enough for a minimal or should I
> go bigger?
>
> thanks much,
>
> scott
The main thing is that, strictly speaking, GRUB does not support RAID, so you
need at least one non-RAID partition as a /boot partition. I say strictly
speaking, because you can set up the /boot partition as RAID-1 which will be
invisible to GRUB bootloader in the MBR.
You can overwrite the original installation or leave it there as an emergency
recovery system. Personally, if you use LVM to manage your other partition(s)
I think I just would leave the original system in place. Then, if you want to
resize the logical volumes on the second partition you can do so safely by
booting into the recovery system.
I would suggest going larger than 200MB, but I'm not an expert and not really
sure just what the absolute minimum is. I think I would use 512MB as a
minimum and 1GB as a maximum. As cheap as disk drives are these days, why
worry about a few megabytes?
Cheers!
cmr
--
Debian 'Etch' - Registered Linux User #241964
--------
"More laws, less justice." -- Marcus Tullius Ciceroca, 42 BC
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