On Mon, 2014-01-20 at 19:07 +0000, Ron Leach wrote:

On 20/01/2014 18:29, Phil Turmel wrote:

quoted

Let me clarify:  /dev/md0 should be a v0.90 or v1.0 raid1 for /boot, no LVM.

 >
 > /dev/md1 is an LVM PV for the OS.


Ok.  That means I need physical partitions for those, on each of the 
drives.

Since I am using 3TB drives, I'll need to use a GPT which, if I 
understand correctly, requires to reveal a dummy 'partition' to make 
the BIOS think there is a boot sector thingy there.

So I'm assuming to pre-partition the physical devices this way:

/dev/sd[x]1 - 64k (? I'm checking the docs) empty, for BIOS to see

I've set mine to 1MB (bios boot, EF02 in gdisk) this means it aligns
nicely on the 1 MB partition as does its start position 2048 sectors on
a 512e drive.

/dev/sd[x]2 - 128 MB /boot v0.90/v1.0 RAID1, /dev/md0

I'm not sure here, but I have no problems using a 1.2 metadata
partition... I think the reason it works is that the stuff in biosboot
contains everything needed to boot, the "boot" directory is not needed
with biosboot as its only a temp staging area used to build the boot
loader which is then copied to the biosboot... 

I would check this for yourself just to be sure; I recall I kept it as a
seperate partition due to a miss-understanding and/or it seemed the
"right way" at the time.

/dev/sd[x]3 - remainder ~3 TB for LVM, v1.2 RAID1, /dev/md1

and then make the two RAID1s, and then create the LVM.

quoted

Having root in an LVM allows strange things like relocating and/or
resizing it on the fly.  Particularly handy if physical access is difficult.

Yes, it was that potential aspect that set me deciding to try your 
approach.  Functional demands on our systems keep changing.

Much appreciated, Ron
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