Hi Gregory,
On Sun, 2006-04-09 at 18:58 -0400, Gregory Maxwell wrote:
Er narf. No. Internet routing is not that stable.
If you anycast TCP on the public internet you *will* end up with oddball behavior as routing topology changes where users get hung connections because the route changed out from under them.
OK, I didn't realise it was actually unstable like that. Maybe you could keep a backup group of servers dormant, not advertising their BGP range, but monitoring the availability of the main group, and staying in sync. Then if the main group goes down, the backup starts advertising immediately.
Another option might be for the backup group to advertise constantly, but with a priority so much lower than the master, that nobody will ever route to them until the master goes down.
You lose load balancing, so it costs more to maintain the same capacity, but you might not need much for a read-only mirror, I don't know.
Getting such a thing working correctly is quite a big more complex then you seem to think it is.
I appreciate the lesson, thanks!
Last I checked we still had issues getting mysql replication working well across non-local networks.
Maybe I can help with that? I've been a MySQL replication admin as well. I thought it was possible to run a Wikipedia read-only server from a flat file copy of the database, without using mysql?
For what you propose the portable block would have to contain all the normal Wikipedia traffic. I some how suspect that they would rather not be tunneling several hundred mbit/sec of traffic. :)
For the right price, they would :-) I guess it depends how much you pay for hosting right now, whether it would be affordable to work this way. But you're right, it might not be (or only as a backup).
Cheers, Chris.