Install guide

and load balancing. Host-based RAID operations compete for resources and could compromise

throughput on the database server.

Many storage topologies include FCP switch infrastructure and this can be used to isolate the I/O traffic

to the array. We recommend that the storage array HCAs and the four ports of the two HBAs all be

placed in one zone. For more information on HBA configuration see Section 3.2.2, “Multipath

Configuration”.

We do not recommend the multi-purposing of a storage array. Many customers buy very large arrays

and place multiple Oracle databases (including dev and test) all on one array. This is ill advised, and the

write-back cache policies in the array (which will become the bottleneck) are difficult to tune. Relative to

the cost of Oracle and the critical nature of most Oracle databases to their respective enterprises, the

storage is free; dedicate the storage, if possible. Oracle workloads are voracious, and unpredictable

consumers of arrays.

2.2.1. Storage Allocation

Red Hat Cluster Suite requires a single, 64MB LUN for quorum disk support. It is recommended that the

qdisk feature be used for Oracle Cold Failover.

RAC/GFS Requirement

The qdisk feature is mandatory for RAC/GFS clusters.

RAC/GFS clusters require Oracle Clusterware to be installed, and they require five 384MB LUNS (two for

registry, three for quorum). It is recommended that three Clusterware voting (quorum) disks be

configured, but a single, externally (array) redundant Clusterware vote disk is fully supported.

In either the HA or RAC/GFS install, the LUNs will be used to create file systems. Oracle supports AIO

and DIO for both EXT 3 and GFS; this provides raw device performance. In our configuration, the

performance of any given LUN is the same; the size of the LUN does not affect performance. However,

the size of the LUN may affect filesystem performance if large numbers of files are placed in many

directories. Most Oracle databases use a relatively low number of datafiles in a file system, but this is at

the discretion of the DBA and is determined by the ongoing operational requirements of the database.

Tablespaces consist of datafiles, and contain base tables and indexes. T ables are indexes are usually

in separate tablespaces (if you are lucky) and the datafiles are usually created to be as large as

possible. In some cases, tablespaces and datafiles are intentionally created small, with AUT OEXET END

disabled. This generates alerts that cause DBAs to be notified of dynamic growth requests in the

database. No two shops have the same policy towards AUT OEXTEND.

Redo Logs, UNDO tablespaces and Redo Archive logs often get their own file system. Redo log file

systems normally have write latency sensitivity, and can be impacted by an Archive log switch

(ARCHIVELOG is usually enabled for production databases).

Red Hat Enterprise Linux 5 Configuration Example - Oracle HA on Cluster Suite