Re: pg_upgrade and rsync

On Thu, Jan 29, 2015 at 10:21:30AM -0500, Andrew Dunstan wrote:
> 
> On 01/29/2015 12:26 AM, Josh Berkus wrote:
> >>So, for my 2c, I'm on the fence about it.  On the one hand, I agree,
> >>it's a bit of a complex process to get right.  On the other hand, it's
> >>far better if we put something out there along the lines of "if you
> >>really want to, this is how to do it" than having folks try to fumble
> >>through to find the correct steps themselves.
> >So, here's the correct steps for Bruce, because his current doc does not
> >cover all of these.  I really think this should go in as a numbered set
> >of steps; the current doc has some steps as steps, and other stuff
> >buried in paragraphs.
> >
> >1. Install the new version binaries on both servers, alongside the old
> >version.
> >
> >2. If not done by the package install, initdb the new version's data
> >directory.
> >
> >3. Check that the replica is not very lagged.  If it is, wait for
> >traffic to die down and for it to catch up.
> >
> >4. Shut down the master using -m fast or -m smart for a clean shutdown.
> >  It is not necessary to shut down the replicas yet.
> >
> >5. pg_upgrade the master using the --link option.  Do not start the new
> >version yet.
> >
> >6. create a data directory for the new version on the replica.  This
> >directory should be empty; if it was initdb'd by the installation
> >package, then delete its contents.
> >
> >7. shut down postgres on the replica.
> >
> >8. rsync both the old and new data directories from the master to the
> >replica, using the --size-only and -H hard links options.  For example,
> >if both 9.3 and 9.4 are in /var/lib/postgresql, do:
> >
> >rsync -aHv --size-only -e ssh --itemize-changes /var/lib/postgresql/
> >replica-host:/var/lib/postgresql/
> >
> >9. Create a recovery.conf file in the replica's data directory with the
> >appropriate parameters.
> >
> >10. Start the master, then the replica
> >
> >
> 
> I find steps 2 and 6 confusing.

For number 2, he is creating a new cluster on the master server.  For
#6, he is just creating an empty data directory, though this is not
required as rsync will create the directory for you.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + Everyone has their own god. +