Re: Distributed Database
From: Alan Connor (zzzzzz_at_xxx.yyy)
Date: Tue, 16 Dec 2003 00:59:00 GMT
On 16 Dec 2003 00:22:17 GMT, Jem Berkes <email@example.com__org> wrote:
>> Let's say that I have a database distributed among 20 boxes, all at
>> different locations with different IPs.
>> The full database takes only 5 of these boxes, so there are 3 mirrors.
>> Can someone tell me the best way to set things up so that a client can
>> just enter a URL and access whichever group of 5 boxes currently
>> isn't being used to capacity? How to connect those 5 boxes together
>> so that they are effectively ONE box?
> To answer your first question, using DNS you can assign multiple IP
> addresses to a single host name. For instance, if IPs A, B, C, D, E are
> address records for db.example.com' then accessing http://db.example.com
> will send traffic to one of those 5 IP addresses in a load-balanced
> fashion. Typically the IP you get is random (I think?)
DNS keeps track of the load on the individual IPs?
So each mirror would have one box whose IP was listed by DNS.
What if the listed box in a mirror went off line and was
replaced by another one? Can you change the DNS records quickly?
Can the mirror, regardless of the IPs composing it at the moment,
be assigned an IP?
> As for connecting the 5 independant hosts together so that they are
> effectively one, maybe rsync is the way to go to synchronize the
rsync looks interesting. Would probably work.
> Jem Berkes
Perfect. And no wasted words, as usual. Thanks Jem.