Re: NetBSD 8: Install on an LVM partition

[Michael van Elst <mlelstv%serpens.de@localhost>]

On Mon, Feb 25, 2019 at 12:10:53AM -0800, John Nemeth wrote:

>      Speaking of our old lvmtools, it does weird stuff when setting
> up multi-terabyte PVs.  Looks like it has a 31/32-bit limit somewhere.
> If you just leave it be, it won't use the entire disk.  If you
> specify the size, it gives warnings, but appears to work fine.  I

I'm using it on 6TB disks.

Obviously you have problems if you use it on disklabel partitions that
are limited to 32bit block numbers (i.e. 2TB for 512byte/sector disks).

This is also true when using the raw partition. While access to the disk
is bounded by the real size, the disklabel can only store a 32bit number
(which is nowadays clamped to the maximum, not just the low 32 bits).
The dm driver uses getdisksize() to report device information to
LVM and getdisksize() uses DIOCGPARTINFO to retrieve the partition data.
It doesn't specially treat the raw partition differently, maybe it
just should.

This can also be a problem if a fictious disklabel partition aliases
a wedge. In that case you need to tell LVM to filter out the unwanted
devices.


Greetings,
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."