Oracle RAC Interconnect, PowerVM VLANs, and the Limit of 20
Hello,
Our company has a requirement to build a multitude of Oracle RAC clusters on AIX using Power VM on 770s and 795 hardware.
We presently have 802.1q trunking configured on our Virtual I/O Servers, and have currently consumed 12 of 20 allowed VLANs for a virtual ethernet adapter. We have read the Oracle RAC FAQ on Oracle Metalink and it seems to otherwise discourage the use of sharing these interconnect VLANs between different clusters. This puts us in a scalability bind; IBM limits VLANs to 20 and Oracle says there is a one-to-one relationship between VLANs and subnets and RAC clusters. We must assume we have a fixed number of network interfaces available and that we absolutely have to leverage virtualized network hardware in order to build these environments. "add more network adapters to VIO" isn't an acceptable solution for us.
Does anyone know if Oracle can afford any flexibility which would allow us to host multiple Oracle RAC interconnects on the same 802.1q trunk VLAN? We will independently guarantee the bandwidth, latency, and redundancy requirements are met for proper Oracle RAC performance, however we don't want a design "flaw" to cause us supportability issues in the future.
We'd like it very much if we could have a bunch of two-node clusters all sharing the same private interconnect. For example:
Cluster 1, node 1: 192.168.16.2 / 255.255.255.0 / VLAN 16
Cluster 1, node 2: 192.168.16.3 / 255.255.255.0 / VLAN 16
Cluster 2, node 1: 192.168.16.4 / 255.255.255.0 / VLAN 16
Cluster 2, node 2: 192.168.16.5 / 255.255.255.0 / VLAN 16
Cluster 3, node 1: 192.168.16.6 / 255.255.255.0 / VLAN 16
Cluster 3, node 2: 192.168.16.7 / 255.255.255.0 / VLAN 16
Cluster 4, node 1: 192.168.16.8 / 255.255.255.0 / VLAN 16
Cluster 4, node 2: 192.168.16.9 / 255.255.255.0 / VLAN 16
etc.
Whereas the concern is that Oracle Corp will only support us if we do this:
Cluster 1, node 1: 192.168.16.2 / 255.255.255.0 / VLAN 16
Cluster 1, node 2: 192.168.16.3 / 255.255.255.0 / VLAN 16
Cluster 2, node 1: 192.168.17.2 / 255.255.255.0 / VLAN 17
Cluster 2, node 2: 192.168.17.3 / 255.255.255.0 / VLAN 17
Cluster 3, node 1: 192.168.18.2 / 255.255.255.0 / VLAN 18
Cluster 3, node 2: 192.168.18.3 / 255.255.255.0 / VLAN 18
Cluster 4, node 1: 192.168.19.2 / 255.255.255.0 / VLAN 19
Cluster 4, node 2: 192.168.19.3 / 255.255.255.0 / VLAN 19
Which eats one VLAN per RAC cluster.