[OpenAFS] Moving Volumes

[Derek Atkins]

"Michael Aldrich" <maldrich@reserveamerica.com> writes:

> > > The volumes are rarely modified by staff. They contain static pages for
> my
> > > site. If the RW volume is being moved, can the RO volume take its place
> in
> > > order to ensure no outage?
> >
> > If you're using RO volumes then you're not really moving the volume.
> > What you really do is:
> >         vos addsite <new site>
> >         vos release
> >         vos remsite <old site>
> 
> Understood. Although, by running vos addsite <new site>, this creates a RO
> copy on the new server. Can I create (using vos release) a RW site on the
> same server from the RO volume? The idea here is to retire the old AFS
> server.

Adding a new ReadOnly replication site and moving a ReadWrite
volume are two _separate_ operations, and do not need to happen
simultaneously.  If you already have multiple ReadOnly sites
(which is the logical thing to do), and if the web server is
only accessing the ReadOnly sites, then you can move the ReadWrite
volume whenever you want with zero downtime of the web server.

They way I would do that is...

Assume you have three servers, a, b, and c.  You are trying to
decommission a, and you are adding c.  b is an existing server
that isn't being changed.

1) get into a state where you have:

        RW:     a:/vicepX
        RO:     a:/vicepX, b:/vicepY

2) vos move <readwrite> a X c Z (move from a:/vicepX to c:/vicepZ)
3) vos remsite a X              (remove the old RO replica from a:/vicepX)
4) vos addsite c Z              (add a new RO replica site on c:/vicepZ)
5) vos release                  (copy data to new site on c)

Note that the ordering of the remsite/addsite is because you have
the replica at b.  If you did not have the replica on server b,
then I would move step 3 to the end of the process.

> Thanks
> Mike

-derek

> > There should not be any outage noticed during this series of operations.
> >
> > -derek
> >
> > --
> >        Derek Atkins
> >        Computer and Internet Security Consultant
> >        derek@ihtfp.com             www.ihtfp.com
> >
> 

-- 
       Derek Atkins
       Computer and Internet Security Consultant
       derek@ihtfp.com             www.ihtfp.com