OK that's roughly what I thought. But IME this does not switch things over fast enough to count as a "hot failover". Maybe I'm not aware of a premium service that's available, but my experience has been that DNS updates don't propagate fast enough for this. There are often customers that cannot reach the site after a DNS change for 24-48 hours, or even more in some cases.
IME the problem seems to be that some secondary DNSs (e.g. those provided by some of your end users' ISPs) don't seem to respect TTL in the DNS records, and so they keep stale records without checking for updates, even if you specify a short TTL. This is a problem at the best of times, let alone when your main site has failed. It seems to me that occasionally, some DNSs also seem to miss changes in SOA, which can be disastrous if you move your DNS to a new ISP. As far as I can see, there is no way to get around these glitches because the secondary DNSs are under the control of an ISP that you do not have a relationship with....? Or are the problems I'm describing a thing of the past? > -----Original Message----- > From: Filip Hanik - Dev [mailto:[EMAIL PROTECTED] > Sent: Wednesday 10 November 2004 19:14 > To: Tomcat Users List; Peter Lin > Subject: Re: Multi-Site Clustering? (hot failover) > > > which might also give you the idea, if you control your own > DNS, you could manually switch it over to a new set of IP > addresses when > your old data center blows up. > > > Filip > > ----- Original Message ----- > From: "Peter Lin" <[EMAIL PROTECTED]> > To: "Tomcat Users List" <[EMAIL PROTECTED]> > Sent: Wednesday, November 10, 2004 1:08 PM > Subject: Re: Multi-Site Clustering? (hot failover) > > > normally ISP will offer multi-site load balancing using DNS. In terms > of failover, it generally handled the same way. If an earthquake > swallows the first location, the second site's DNS will pick and route > the traffic to the second cluster. > > I would talk to your service provider. the smaller shops don't offer > it, so you'll have to talk to a bigger ISP. > > peter > > > > On Wed, 10 Nov 2004 12:52:17 -0600, Filip Hanik - Dev > <[EMAIL PROTECTED]> wrote: > > Even a datacenter by itself plugs in to more than one > backbone (network provider) > > So a datacenter itself has more than one connection into it. > > So what I am saying, if you want to fail over between data > centers, that is not something you configure in tomcat, or in your own > > network, that is something you probably arrange with the > data centers or the network providers, cause if your data center gets > > shattered in an earth quake, all the routers in there will > be dead anyway. > > > > Filip > > > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
