Re: [gentoo-user] why does Udisks require Lvm2 ?

[Grant Taylor]

On 6/24/19 12:12 PM, Mick wrote:
> LVM-RAID uses the kernel's mdraid,

Yep.

You can get device mapper command(s) to show the internal / under the 
hood MD devices.

I feel like what LVM does to mirror (RAID 1) devices is complex.  You 
end up with non-obvious LVs that are then raided together to create 
another virtual block device that is what you see as the LV.

There are options about where and how metadata is mirrored.  Some of 
which is stored in the VG and others is stored in another small hidden 
LV specifically for this purpose.  Which itself can be configured to 
have multiple copies.

At least that's how I remember things from about five years ago.

> but with less tools to manage the RAID configuration than mdadm offers:

That's because the standard LVM tools make calls to the kernel to manage 
things.  I never /needed/ anything other than the LVM tools to 
administer LVM RAID.  But I think that you can find the expected things 
under device mapper et al. if you know where to go look.

When I say "hidden", it seems as if the traditional LVM tools simply 
don't expose LVs with specific naming patterns unless you go looking for 
them.  Much like dot files are ""hidden by default, but there if you 
know where and how to look.



-- 
Grant. . . .
unix || die