(apologies for cross-posting)
On either Thursday or Friday of this week, Giuseppe Lavagetto (of the
Wikimedia TechOps team) and I are planning to migrate <
https://test.wikipedia.org/> (testwiki) to HHVM. The way testwiki is
configured makes it a natural next step on the path leading from the Beta
Cluster to production. Specifically, testwiki is served by the same
load-balancer, reverse-proxy, and database servers as the rest of
production, but it is powered by a single application server that is
segregated from the pool of servers that handle requests for all other
Wikimedia wikis. This means that if we run into stability issues with HHVM,
they will be confined to just testwiki, and will not spill over to other
sites.
To migrate testwiki to HHVM, Giuseppe will need to take the server that
powers testwiki off-line for several hours for re-imaging. Ordinarily, we
design our infrastructure for redundancy and graceful failover, so we can
take machines offline without impacting users. But the corollary to
testwiki being a special case is that it is not configured in this way. As
I explained above, this is just as well, because it means we can perform
this work without disturbing the rest of the cluster.
Giuseppe and I will provide additional notices via IRC and e-mail prior to
beginning this work. We know that testwiki is used by a diverse user-base
to test various MediaWiki software components and will do our best to
minimize disruption to such users. Feel free to get in touch via e-mail or
IRC (my nickname is 'ori') if you have concerns about the deployment.
Thanks for your patience and understanding! :)
Ori