[linux-lvm] Re: [ANNOUNCE] LVM reimplementation ready for beta testing

[Alan Cox]

> But "flushes all pending io" is *far* from trivial. there's no current
> kernel functionality for this, so you'll have to do "weird shit" that will
> break easy and often.
> 
> Also "suspending" is rather dangerous because it can deadlock the machine
> (think about the VM needing to write back dirty data on this LV in order to
>  make memory available for your move)...

I don't think you need to suspend I/O except momentarily. I don't use LVM and
while I can't resize volumes I migrate them like this

	mdhotadd /dev/md1 /dev/newvolume

[wait for it to resync]

	mdhotremove /dev/md1 /dev/oldvolume

the situation here seems analogous. You never need to suspend I/O to the
volume until you actually kill it, by which time you can just skip the write
to the dead volume.

(The above procedure with ext3 does btw make a great backup system 8))

Alan