[HyperDB] multi-datacenter configuration

[Beck, Joe]

We¹re looking to migrate to a multi-datacenter configuration & the 2 most
obvious challenges with wordpress are DB and wp-contents contents.
This post is focused on DB:
Can anyone speak to architecture options here.
I¹ve read that wordpress.com has 3 data centers but I believe its only using
master ­ slave replication.
if this is the case, are you just using mysql replication to keep all dbs
across data centers in sync?
And more specifically, how do you direct any writes (article posts or
comments submitted) to the master db to do the write?
this goes back to orig question on whether you only have a single master
that resides in 1 of your data centers.

I realize that hyperDB has some capabilities to support multi-DC but I
needed to get the above question answered before even looking closer at
that, at least I think I do.

Thanks for any feedback,
Joe