Notes From A 10g RAC Workshop
Table of Contents
RAC FACTS & FIGURES
- Oracle 10g (Release 1) can support up to 64 nodes.
- Oracle 10g (Release 2) can support up to 100 nodes.
- Oracle RAC adopts the Stripe And Mirror Everything principle.
- Oracle 10g uses ASM to stripe all data across all disk groups in non-configurable 1 MB chunks.
- Oracle 11g maintains the *1 MB* chunk size by default, but this is now configurable.
- By default, whenever a new disk group is added to ASM the database will begin to spread the data over the new disks. This behaviour can be throttled back, or even suppressed, by adjusting the ASM_POWER_LIMIT parameter.
- In Oracle 10g the cluster software was known as Cluster Ready Services and was used purely to manage Oracle software, e.g. database, ASM.
- In Oracle 11g the cluster software is now known as Oracle Clusterware because the API has been released to the general public so that non Oracle software can be managed, e.g. Apache web servers.
- All clusterware configuration settings and dependencies are stored in the Oracle Cluster Registry and can be managed using a host of crs_ commands.
- The heartbeat process on each node performs two operations every 1 second. Firstly, it updates the OCR with the fact that itself is alive, and secondly it updates the OCR with the results from the polling it has made to its cluster partners.
STRETCH RAC INFORMATION
- The furthest configured stretch RAC configuration is 30 miles - as of 21 April 2008.
- Regardless of infrastructure, oracle will support any stretch RAC configuration that can support a 2 ms roundtrip time for the heartbeat.
- When configuring a stretch RAC cluster it is preferable to have a third location available to house the voting disk. This way, there is an independent adjudicator of which node(s) should be ejected from the cluster in the case of a failed interconnect. If a third location is not configured, and the interconnect breaks, the node with the lowest instance id will assume control.
- Before installing the Oracle RAC software it is desirable to run the following command to ensure that all pre-requisites are met:
- cluvfy comp peer -n <node 1>, <node 2>, <node n> | more
- Installing RAC software on a single node, that doesn't as yet have a cluster partner, is possible, however it will require a leap of faith as the pre-requisites cannot be checked before installation begins.
- tnsnames.ora is no longer necessary. In order to connect to a service without a tnsnames.ora entry, use the following syntax:
- sqlplus <user>/<password>@//<node>/<service>
USEFUL WEB SITES
- Building RAC On A Single Node Using Virtual Machines
- Build Your Own Oracle RAC 10g Release 2 Cluster On Linux And !FireWire