Miguel Veliz wrote:
I read several threads on this and apparently there is a need for a routing daemon to be running. Why is there the need for a routing daemon?
A routing daemon is needed to tell the other parts of your network how to reach your VIPA(s). Ideally, for maximum availability, your VIPAs should not be in the same subnet as any of your physical interfaces (and your physical interfaces should not be in the same subnet, but this is becoming less important). Because your VIPAs are in a different subnet, your neighbouring router cannot reach your VIPA directly any more -- it needs an entry in its routing table to know how to reach the VIPAs.
What exactly should this daemon do?. Re-route incoming packets to the "physical" interface that is up when the other one is down dynamically.
Because you have multiple physical interfaces through which traffic can reach your VIPAs, and you want failures to be routed-around automatically, the routing daemon tells neighbouring routers how to reach your VIPAs. If one of your physical interfaces (or one of the neighbouring routers) fails, the network will learn that that path is no longer available and your VIPA stays contactable automatically. I believe this to be key in a VIPA implementation. Without a dynamic routing daemon, you would have to recover manually (by recoding static routes, etc). IMHO, you have lost much of the value VIPA offers. A dynamic routing daemon is not involved in the actual transmission of packets. All it does is provide information to neighbouring routers about the networks you can reach, and provide information to your own kernel regarding the networks that other routers can reach.
What is IPA takeover is used for?.
IPA takeover is the capability for another host in your environment to take on the VIPA addresses of a primary host should that primary host become unavailable. It lets you implement a kind-of "hot-standby" system where multiple servers running an application are available, but only one (the one where the VIPA is active) is receiving the traffic. If that host fails, IPA takeover allows the IP address(es) to be "moved" to one of the standby hosts.
Is IPa for a manual take over procedure?
I'm not sure about this -- I would hope it was automatic. If it is manual, I can think of a better way to do the same effect in an automatic way :)
Do I need to set IPA takeover along with VIPA
No, IPA takeover is not required for your VIPA to work.
And last , any idea why I am not able to echo "1 or " to the enable folder. I issue the command: echo 1 > /sys/bus/ccwgroup/drivers/qeth/0.0.2210/ipa_takeover/enable The is no error shown or logged, but the set never happens. I do a cat to enable and it comes back 0.
This probably means that some other configuration is required (like setting the IP addresses that you are standby for). I suspect you will need to plug IP addresses into the "add4" or "add6" pseudofiles in ipa_takeover to set it up. Otherwise, there are some driver parameters that can only be changed while the device is offline (fake_ll is an example). Remeber that you only need to do this if you want IPA takeover function -- that is, you have another host that you want to service your VIPAs in the event of the failure of your main host. In that case, the manipulation of the ipa_takeover nodes will happen on your backup hosts, not on the main host. I'd suggest referring to the "Linux Device Drivers" manual on DeveloperWorks (taking my own advice I'm doing the same, since it's been a while since I looked at some of this). Cheers, Vic Cross ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
