[ZODB-Dev] Restoring from repozo and reusing an index file?

[Hanno Schlichting]

On Fri, Jun 11, 2010 at 3:25 PM, Paul Winkler <slinkp at gmail.com> wrote:
> I'm preparing to move a zope site from one host to another. We've been
> planning to use repozo backups to copy the filestorage from the old
> host to the new one.  I'd like to figure out how to minimize downtime
> while not losing any data.  My plan was:

For moving stuff to a new host where a short downtime is planned
anyways, I would just use rsync.

1. While the old site is still running, rsync both the Data.fs and
index file to the new host
2. Make sure you don't run any zeopack operation between that point
and the actual switchover
3. You can keep running rsync a couple times shortly before the
downtime to get the most recent state over
4. Shut down the old site
5. Do a final rsync of both the .fs and .fs.index (this should take a
couple seconds or minutes at most)
6. Start the new site, since the index is up-to-date and matches the
Data.fs it should be seconds as well

I tend to run rsync via "rsync -rP --rsh=ssh". The Data.fs is an
append-only file, so rsync is very efficient at handling it. Only
zeopack rewrites things all across the file and causes a subsequent
rsync to be slow again.

> 1) would it be safe to copy the index file from the old host and just
> use that with the filestorage generated by repozo?

It's save, but it will be ignored and a new index be created, so you
don't gain anything.

But at some point you could upgrade to ZODB 3.10 (currently in beta),
where repozo does save the index file for each backup. It will still
be slower than rsync for this use-case, though.

Hanno