[dm-devel] Re: dm snapshot: allow live exception store handover between tables

[Alasdair G Kergon]

On Fri, Nov 06, 2009 at 02:54:30PM -0500, Mike Snitzer wrote:
> Alasdair G Kergon <agk at redhat.com> wrote:
> > On Fri, Nov 06, 2009 at 02:26:21PM -0500, Mike Snitzer wrote:
> > > OK, actually in practice 'lvchange --refresh' is:
> > > old->suspend
> > > new->ctr
> > Those two need to be swapped.
> Why do they _need_ to be swapped?
 
old->suspend stops I/O to the device.
new->ctr allocates memory and in a bad case might lead to waiting for I/O to
the device we've just suspended.

Alasdair