On Tue, 17 Apr 2012 14:40:10 -0600
Ken Gunderson [off-list ref] wrote:

Apologies for following my own post but I guess should elaborate...

Hello:

I'm wanting to set up a new md root lvm based configuration and after
reading various docs am confused about how I should be going about
this. My intent is to have mirrored /boot and swap partitions and a
raid10 / partition with LVM.

Issue #1: gpt is recommended over mbr based partitioning for new
installs, even on BIOS based systems (presuming these BIOS will boot
gpt, wh/mine do). Auto-assemble is not recommended for new
installations (my understanding is that it is not necessary with
initramfs) so I presume I should be specifying partition type DA.
However, while gdisk et.al. allow for selecting type FD, they do not
offer DA as an option.

Per <http://www.rodsbooks.com/linux-fs-code.html>, Linux ignores
partition type codes.  Yet per man mdadm:

"When creating a partition based array,  using  mdadm  with
version-1.x metadata, the partition type should be set to 0xDA (non
fs-data).  This type selection allows for greater precision since using
any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)],
might create prob‐ lems in the event of array recovery through a live
cdrom."

So which is it?  Does partition type code matter to md/mdadm or not?
 

Issue #2: Is there any reason to prefer 1.0 vs. 1.2 metadata? I can
use either grub2 or Syslinux boot loaders.  My understanding is that
Syslinux supports the former while Grub2 supports 1.2. All other
things being equal, I'd prefer to use Syslinux.  Unless there is some
technical reason to favor 1.2 metadata and/or Grub2.

So what would be best practices recommended way to proceed here?

The reason I ask is that I bring such a configuration online on
Archlinux by following these instructions:

<https://wiki.archlinux.org/index.php/Software_RAID_and_LVM>

But I'll be damned if I can recover from failed drive simulations - at
least reliably, as sometimes it works while others not - so I'm just
trying to rule out potential variables here.

Thanks-- Ken

-- 
Ken Gunderson [off-list ref]
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