> From: Richard Chycoski [mailto:[email protected]] > > > AD has excellent failover characteristics - much better than NIS's > slave > server concept. You can have replicas all over the world, all > containing > the same data, and AD will manage replication and failover quite > transparently. And cached tables mean that even if the AD servers go > away for a while, you usually get no interruptions (except that you can > only log in to IDs that have have been logged into on that server > recently). It even works for laptops and other disconnected devices, > just like with a Windows device. If you have logged in to the domain > while connected, you can pull the machine off the net, take it > elsewhere, and you can still log into it. NIS - if you lose contact for > more than three seconds at a critical time, the transaction will fail > and your calling process will usually abort.
While I agree AD has excellent failover characteristics, and I also agree that NIS is not quite as good as AD in this regard, I would say that NIS has excellent failover characteristics as well. Just not quite as good as AD. Every NIS client has a list of servers, which you may populate manually or automatically. During startup, and at regular intervals, it essentially ping's each one, and makes the default server whichever one is responding the fastest. If any one server is not responding, then it triggers another ping scan, and repeats the query to whichever server is able to respond. The failure of NIS happens when your client is removed from the network, or *all* of the servers are removed. The only reason I would say this failover isn't as good as AD failover is: Because in AD there are no mater/slaves. They're all equally authoritative, and replication is automatic. In NIS, when you update something, you have to update the master and push down to the slaves. >From an administrator's perspective, I think AD is better for failovers. >From a client perspective, unless you are talking about a laptop which will leave the network, I think they're both equal. _______________________________________________ Tech mailing list [email protected] http://lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
