Re: gEDA-user: gedasymbols.org down

[Christoph Lechner <cl0023@xxxxxxx>]

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Greg Cunningham wrote:
> On Sat, 2010-02-27 at 09:36 -0600, John Griessen wrote:
>> Greg Cunningham wrote:
>>> Winter in Pennsylvania, summer here in Tasmania.  need rsync & round-robin
>>> dns.
>> Rsync is being used for mirroring, but I'm not sure what the DNS setup is.
>> Ping says it is alternating.  The mirror server was quick for a while
>> after I added an A record at my hosting service's DNS server, but
>> is back to slow unresponsive, and does eventually serve pages after multiple attempts.
>>
>> How do you do round robin DNS?  I think DJs DNS server may still be on and overruling
>> mine.
>>
>> John
>>
> 
> Sorry for the delay, but I have had a major electrical re-fit at work.
> Long day...
> 
> The other guys have answered adequately.
> 
> I spoke without enough thought.  RR dns facilitates load sharing rather
> than redundancy.  Someone else with more experience in fail-over may
> offer a better suggestion.
I don't know what infrastructure is required for the gedasymbols web
site to work.

But I'll assume you run a MySQL database and you need some data volume
mounted as well.

Remote replication/high availability is quite hard to setup, because
it's so easy to get a what HA guys call a split brain situation: The
data on both nodes begins do diverge. Just think of one of the internet
connections going down. I can tell you from experience that split brain
is a real mess.

I've got some experience with high availability using Linux HA (now
called Pacemaker), DRBD (for the block device replication) and MySQL
replication. But in the setups I'm managing, the servers are mounted in
the same rack, with replication connection over gigabit loopback cable.

To change the A record when failover happens one could do an update of
the DNS entry at runtime. But I'm not sure if this can be done for the
gedasymbols.org entry. Of course your provider has to offer this service
to you, maybe quite expensive?

What about not running the server at home, but collocated at a data
center? THat would be somewhat easier to do.

- - cl
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