[consulting] Distributed Loads, Failover and Dynamic Content

[Boris Mann]

On 14-Jul-06, at 5:41 PM, Hugh Esco wrote:

> I'm working with folks who would like to physically
> distribute their server load so that they might be
> prepared for peak demand as well as to provide for fail-over
> as part of a disaster recovery plan.
>
> We're looking at rsync and such for static content.  But
> I'm curious what strategies others might be pursuing for
> syncing two or more servers which are hosting mirrored
> content on dynamic platforms which are subject to local
> manipulation between changes.
>
> I'm imagining some sort of hourly flatfile datadumps, which
> would be diff'd and merged together with hourly restores.
> With DNS round-robin being used to distribute the load.
>
> Or I'm wondering if there is some way to put a trigger on
> every database which is being mirrored, so that every
> transaction against the db that inserted or updated a
> record was logged and simultaneously run against the mirror
> data sets on the remote hosts.

As long as you are talking content only (i.e. nodes), then using the  
publish and subscribe modules would be a good fit.

> Has anyone done something like this before?  Any clues on
> potential strategies would be appreciated.

This is best handled directly at the MySQL layer. Since Drupal  
handles sessions in the database, global load balancing is definitely  
possible. Look into MySQL replication (here's a starting point:  
http://dev.mysql.com/doc/refman/5.0/en/replication.html). That's  
obviously just the tip of the iceberg -- I would recommend finding a  
hosting partner that excels at this stuff and having them handle it  
for you. If you're willing to dive in and learn, it's possible to do  
yourself, but unless you love sysadmin'ing or have the internal  
resources that do -- outsource it.

--
Boris Mann
Vancouver 778-896-2747 San Francisco 415-367-3595
SKYPE borismann
http://www.bryght.com