On 7/20/06, Alex Collins <[EMAIL PROTECTED]> wrote:
I have run up a test based on the network diagram on page 193 of the SRSS 3.1 Admin guide. Is there any reason why I can't just run like this so that either server will fail over to the other.
If you set these machines up as a host group then, on the average, half of the Sun Rays at each site will connect to the machine at the other site. If you have enough bandwidth between the sites for this to be acceptable (you say you have plenty of it) then there is one remaining technical requirement and a couple of operational issues that you need to consider. The technical requirement is that in order to function as a host group the machines need to be able to exchange group membership discovery traffic. This is usually sent as multicast traffic but you can choose to use broadcasts instead of you wish. Officially the machines are supposed to have a direct connection to at least one subnet in common so that broadcast can be used if multicast turns out to be unreliable but if you're confident that multicast propagates dependably on your network you might decide to risk ignoring that requirement. The archives of this list contain detailed discussion of this issue. For starters, run 'utgstatus' on the machines as they exist today. That will tell you whether they can already "see" each other for the purposes of group membership. The first operational issue is that the Sun Ray Data Store, which provides the configuration repository for all members of a group, has a single-master architecture. One machine is more important than the others, and if that machine is unavailable then no Data Store updates can be performed. (The other machines carry read-only copies of the DS content: all updates are applied at the master, or "DS primary", and then fed back to the DS secondaries.) This isn't usually a big deal but it will increase your operational risk a little. You should satisfy yourself that the risk will be more than offset by the load-sharing and availability gains before you take the plunge. The second is that if one machine goes down then, provided that DHCP is still available, all of the Sun Rays will get a session on the remaining machine. Is one machine able to support the full Sun Ray population? If you're at all unsure about the inter-site bandwidth being adequate then before you do anything with a host group you could run an experiment by adjusting DHCP so that it sends all of the Sun Rays at one site to the server on the other site. Do this in both directions for a worst-case scenario. A few hours of running in that configuration will confirm whether your bandwidth really is sufficient. Doing this in one direction only will place all of the Sun Ray sessions on one machine, which will tell you whether one machine can handle the full load. OttoM. __ ottomeister Disclaimer: These are my opinions. I do not speak for my employer. _______________________________________________ SunRay-Users mailing list [email protected] http://www.filibeto.org/mailman/listinfo/sunray-users
