[Xen-users] Re: LVM's inside of Domu's

[Ferenc Wagner <wferi@xxxxxxx>]

Donny Brooks <dbrooks@xxxxxxxxxxxxxxxx> writes:

> Possible drawbacks to having LVM in domu:
> cannot mount /dev/foo/lv from dom0 and see filesystem

You can, but be careful: you can activate the domU's VG in the dom0 even
while the domU is still running, but you mustn't do any LVM operations
during this period (unless you use clvm, which is probably overkill).
Contrast this with mounting the domU's file system on the dom0 while
it's still mounted on the domU: this is ALWAYS a disaster (unless you
use some cluster file system, which is probably overkill).

Based on this, I always use a strict filter in my lvm.conf in the dom0,
so that it can't accidentally activate the domUs' VGs.  If I want to
mount some domU filesystem on the dom0, I extend the filter to include
the given dom0 LV (which is a PV from the domU's point of view),
activate the domU's VG (all my VGs have different names, and yours
should, too: just use the hostnames), do my business, deactivate the
domU's VG and close down the filter again.  This works and is rather
safe.

> possible slowdown?

That shouldn't be measurable.
-- 
Cheers,
Feri.

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