Search Again: Re: Load Balancing - how to From: Men & Mice Support Date: Friday, August 23, 2002 Time: 2:40:50 pm OK, a little clarification is in order. When both servers are up, the preference values determine how much traffic hits each server. These numbers can be between 1 and 65535. If you have to servers with preferences of 65535 and 1, respectively, then the first will get 65535 out of every 65536 hits. In theory, anyway. When either server goes down, no traffic is sent to it. Simple as that. All traffic is rebalanced between the remaining servers. If all servers are down, the system goes into round-robin mode. Now, for the technical details and limitations that you need to know: - The QuickDNS server finds out that the web server is up or down by periodically establishing an HTTP connection to it. (The frequency of these checks is set by the Interval setting.) - It's not QuickDNS Server that establishes these connections, it's QuickDNS Load Balancer. So you must have Load Balancer running on each DNS server to make it all work. - If a given web server does not respond to the HTTP connections every Interval seconds for a total of at least Hostlife seconds, then it will be considered "down". After that, the TTL must expire before outside servers will ask again for the IP address, so it may take up to TTL seconds before all new traffic is diverted away from the down server. - A given web browser only checks for the IP address of the server at its first contact with that server hostname. So if a web user is already on the site when a server goes down, they may not be able to get to your other web server until they quit and relaunch their web browser. - Some bad DNS servers ignore TTL's and cache data for inordinately long periods of time. If you are unlucky enough to have one of these servers cache the IP address of your failover server, that DNS server's users will think your website is down for maintenance for several weeks. - As of QuickDNS 4.0, there is no longer going to be a classic Mac OS version. That means no more load balancing system. ____________________________________________________________________ Chris Buxton Men & Mice support@menandmice.com Making DNS Easy At 8:10 PM +0100 8/22/02, David Hooper wrote: >I would like to know how to do this too - for exactly the same reason as >Tim. I did not quite follow what to do from Matthias (sorry!). > >David > >> From: Jeff Logan <jeff@insideout.com> >> Reply-To: "QuickDNS Talk" <quickdns-talk@lists.menandmice.com> >> Date: Wed, 21 Aug 2002 17:49:18 -0700 >> To: "QuickDNS Talk" <quickdns-talk@lists.menandmice.com> >> Subject: Re: Load Balancing - how to >> >> I have this same question as well. A good answer from Chris or >> Sigfus will help. >> >> Thanks, >> Jeff Logan >> >> >>> Hi there, >>> >>> We're running QuickDNS 3.5.3. It has many great features, but I can't >>> believe there is nothing in the manual about Load Balancing (a >>>quick mention >>> of Round Robin Load Balancing, and even THAT was hard to find). Even after >>> spending the best part of an hour and a half scouring through the talk list >>> archives, I still only have half an idea of what to do... >>> >>> Isn't that a bit strange that there's a feature which can be accessed under >>> 'insert a record' but there's no explanation at all of what it is or how to >>> use it?!?!? >>> >>> Now to the question: >>> >>> This is what I've tried. In the load balance window, I've entered the name >>> of a host I want to balance, I've entered TTL 300, Interval 30, >>>Hostlife 60. >>> Under host address and preference, I've assumed that I put IP address and a >>> number. Is the preference number a percentage, or just a number. If i put >>> the 'primary' as 1000, and the other as '1', does this mean it will be >>> accessed 1 out of every 1001 tries. >>> >>> In this case, what happens if the primary host is down (which is actually >>> the reason we are trying this)? >>> >>> To explain further, our 'main' webserver hosts a number of sites which have > >> complicated database interactions. If this server is down for a bit of >>> maintenance, we would like all queries to be directed to backup webserver >>> which could just say 'server down for maintenance yada yada'. And then when >>> the primary is up again, all queries to go back to that. >>> >>> All assistance would be greatly appreciated. >>> >>> Regards, >>> Tim >>> -- >>> Tim Robinson >>> IDFK Web Developments >>> tim@idfk.com.au >>> 114a/40 Yeo Street >>> Neutral Bay 2089 >>> Australia >>> Phone +612 9908 2134 >>> Fax +612 9908 4837 >> >> >> ------------------------------------------------ >> InsideOut Marketing and Web Solutions >> Web, Marketing and Print Design >> Toll Free: 1-800-500-8401 >> Phone: 360.683.5774 Fax: 360.683.5857 >> Email: mailto:jeff@insideout.com >> 229 South Sequim Ave, Sequim, WA 98382 >> http://www.insideout.com >> ------------------------------------------------ >>

Messages In This Thread: Load Balancing - how to by Tim Robinson on Aug 21, 2002 at 5:46:40 pm Re: Load Balancing - how to by Jeff Logan on Aug 21, 2002 at 5:50:22 pm Re: Load Balancing - how to by Matthias Gruber on Aug 22, 2002 at 2:09:02 am Re: Load Balancing - how to by David Hooper on Aug 22, 2002 at 12:11:36 pm Re: Load Balancing - how to by Men & Mice Support on Aug 23, 2002 at 2:40:50 pm