Re: [linux-lvm] Cluster LVM

[Remco Post <r.post@sara.nl>]

> 
> --- Joe Thornber <joe@fib011235813.fsnet.co.uk> wrote:
> > On Thu, Feb 28, 2002 at 05:03:37AM -0800, Prashant
> > Kharche wrote:
> > > 
> > >   Basically, we are putting a lock on the VG while
> > it
> > > is getting resized or for any tool which tries to
> > > access VG .. So that no other user can access the
> > > metadata of that VG.. 
> > > WE ARE ONLY MATAINING THE CONSISTENCY OF THE VG
> > > METADATA.. 
> > > We thought of protecting VG DATA (NOT METADATA),
> > but
> > > it becomes very completed.. so as if now we are
> > not
> > > taking care of FS access..  
> > 
> > You need to take care that the volume groups running
> > on all nodes
> > *always* reflect the metadata on disk.
> > 
> > For instance, if have two nodes running vg0/lvol0,
> > and I issue a
> > pvmove from node1, when does node2 find out that the
> > mapping has
> > changed ?
> > 
> > - Joe
> > 
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm@sistina.com
> > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at
> http://www.sistina.com/lvm/Pages/howto.html
> 
> when node1 issues a command pvmove, LOCK MANAGER will
> block all the nodes from accessing the METADATA for
> that VG and as soon as it finishes updating the
> METADATA, pvmove itself writes the updated kernel VGDA
> on the DISK.. so for this period, METADATA consistency
> is maintained. 
> 

During the pv move, not only needs the metadata be protected, but also the fs 
data,eg. when one server is moving a data block from one disk tot the other, 
all other servers must be notified that that block is currently inaccessable, 
so no fs data will get lost during transaction, or am I missing something here?


-- 
Met vriendelijke groeten,

Remco Post

SARA - Stichting Academisch Rekencentrum Amsterdam
High Performance Computing  Tel. +31 20 592 8008    Fax. +31 20 668 3167

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