Install guide

Tip

During a log switch, the previously closed log is copied to the archive destination, and is usually

not throttled. T his can impact transaction commit response times. One of the simplest ways to

mitigate this effect is to place the Archive Log destination on DIO-enabled NFS mount, and the

network connection be forced to 100TX. This is the easiest way to throttle archive log copies.

Customers often use NFS as an archive log destination, so this can be as simple as a NIC re-

configuration request.

A LUN (and subsequent file system) should be allocated for ORACLE_HOME. This file system should not

contain any database files. T his LUN must only hold the product home, and spare capacity for trace files.

It could be as small as 8GB.

RAC/GFS Requirement

For RAC/GFS, Oracle Clusterware Home (ORA_CRS_HOME) cannot be located on a clustered GFS

mount point.

Virtualized Storage

Like virtualized anything else, Oracle and virtualization tend to make very strange bedfellows.

Oracle database applications are voracious consumers of hardware resources and rarely share

well with other applications, and often not well even with the host OS. Oracle is a fully portable OS

that is completed implemented in user space. It is best to dedicate the hardware to Oracle, and

this goes for the storage array too. EMC invented “virtualized” storage years ago with the concept

of busting up a single, big disk into four pieces, or Hypers. T hese Hypers combine in a way that

create a Meta LUN. T his looks like a highly efficient utilization of storage, but misses the point -- A

15K drive busted up into four pieces, does not serve four times the IOPS. If you run several

instances of Oracle on a virtualized server and several copies of Oracle databases on a

virtualized storage array, your life will be much harder (and very likely shorter).

2.3. Network Topology

There are only two main network pathways used by the cluster: the frontside, or public, and the

backside, or private, cluster interconnect network.

Clients or application servers mostly use the public network in order to connect to the database. When a

node fails, existing transactions, sessions and connections disappear and this can create an

interruption in service to these connections. T he decision to deploy Cold Failover or RAC/GFS depends

on how fast connections and transactions must restart. Cold Failover does not preserve any state, but

can still restart very quickly, without having to reconstruct, re-connect, and re-synchronize with the

application. RAC provides the ability to preserve much more context about sessions and transactions. If

configured properly (including the application tier), this can dramatically reduce the downtime, but it

increases both cost and complexity.

The most difficult situation is with existing connections that have opened a T CP/IP socket to the

database. When the database node fails, the client socket needs to be notified as soon as possible.

Most JDBC drivers now use out-of-band signaling to avoid the dreaded hung socket. Connection pools

Chapter 2. Hardware Installation and Configuration