Re: [linux-lvm] pvresize patch pending

[Alasdair G Kergon <agk@redhat.com>]

On Fri, Oct 28, 2005 at 07:37:27PM -0500, Zac Slade wrote:
> I think that to get this part write might take a fundemental shift in the way
> pv_write() and _pv_write() behave.  What would be nice is to make pv_write()
> distinguish between a pv_create calling it and a pv_resize.  Then have _pv_write
> only write the pv mda to the disk.  By doing this _pv_write becomes generic and
> allows for further extension.  Also then we can probably implement atomicity for
> pv updates (though updating a pv was not initially engineered into lvm it can
> become very handy).
  
I'm reluctant to extend pv_write - long term I want to get rid of it
(and pv_read also) as PV operations are always awkward and getting in the way.
Everything should be done with (new-style) VGs and LVs.

pvcreate is also superfluous - I want to absorb it into vgcreate/vgextend etc.
So every labelled volume will always belong to a VG - with enhanced
vgsplit/vgmerge & allocation facilities.
CVS now lets you create PVs on LVs - another step towards eliminating
PVs. 


> Actually there is no need to use process_each_pv

If you don't use it, you have to duplicate the logic in it as you have
already done - incompletely (e.g. tag support is missing).

> necessary or even wise to support resizing more than one pv at a time.  

If ppl want to do that, why stop them?


> Can't we just borrow the code from pvcreate to manipulate the metadatacopies? 

Not yet.  That problem needs solving as part of a general mda-manipulating  
feature.  No point in doing it first for a rarely-used case.

Alasdair
-- 
agk@redhat.com