I have a few queries on how Oracle CLusterware, Oracle RAC and 3rd party clustering fit with each other –
Q1. My understanding is that Oracle Grid Infrastructure / Clusterware is Oracle’s Clustering solution that you can use to cluster applications ? i.e. it’s a general clusterware solution to rival those already on the market. Is this correct ?
Q2. So why is RAC needed for clustering Oracle Databases ? Is an Oracle Database not simply regarded as an application like any other ? Therefore why can you not simply use GI / Clusterware to cluster it as you would for any other application ? Why so you have to put RAC on top of Clusterware ?
Q3. Is it possible to cluster an Oracle Database using 3rd party clustering and not use Oracle Clusterware and RAC at all i.e. can you say cluster an Oracle Database using say Sun Clusters, AIX Clustering or even native clustering in Linux ?
Q4. If RAC is purely for clustering Oracle Databases – then what’s with the title ‘Real Application Clusters’ ? What’s Real about it ?, What’s Application about it ?
Q5. I have also read that RAC can use 3rd party clustering. However if you choose this to be the case, then you still need to install Oracle Clusterware anyway ( I believe in order for the Interconnect to be created to allow for Cache Fusion between the node Instances ? ).
Is this the case ? If so why would you ever bother with 3rd party clustering ? - since you are going to have to install Oracle Clustering anyway – and presumably have to license it ( all I can think of is the scenario that you already have a 3rd party cluster in place and you decide you need to use the same hardware for a database cluster ) ?
Any wisdom greatly appreciated,
Jim