RE: Apache clustering w/ load balancing and failover
Mathieu Martin wrote:
> Mario Lopez wrote:
> >>Why not using 'roundrobin' ???
> >>Install a couple of Web-Servers, give each Server an IP and
> >>then setup for each Server a A-Record on your DNS-Server
> >>pointing to the same hostname.
> >The problem with round robin is that when one server fails
> over it keeps sending them connections, I once saw a DNS
> server implemented in Perl which worked in a round robin
> fashion but making some kind of test to know if the server
> was up and running correctly, I remeber it was called
> something like "lb-named"
> Why not use (keepalived?) with round robin dns then?. You get load
> balancing, redundancy, and you don't need unnecessary additionnal
> servers or kernel patches or whatever. Even with a lot of servers, it
> should scale pretty well. Works too with servers in several
> locations on
> different internet pipes, as long as there are at least two
> servers on
> each pipe for redundancy.
You're wrong. round robin dns isn't HA, isn't load balancing, it's just
request spreading. You can't control how many (DNS-)clients cache one of the
RR IP's, therefore you won't get even load on your RR'ed servers.
Plus you _have_ to use a tool like "lb-named" to keep your round robin dns
from giving out the IP of a failed server.
It really comes down to using LVS+(keepalived|heartbeat|...) or pen.