Red Hat LINUX ADVANCED SERVER 2.1 - Informations techniques télécharger pdf (Page 15)

Tips and Techniques: Install and Configure Oracle9i on Red Hat Linux

Advanced Server

Process: Maximum number of 16384 processes, per user, can be set by executing

ulimit -u 16384

Semaphore

Recommended values for various semaphore variables are as follows:

SEMMSL - The largest PROCESSES parameter of any Oracle database on the

system plus ten. The minimum recommended value is 100

SEMMNS - Sum of the PROCESSES parameter for each Oracle database, adding

the largest one twice, and then adding an additional 10 for each db. The minimum

recommended value is 256

SEMOPM - Defines the maximum number of operations per semop call.

Recommended value is 100

SEMMNI - Defines the maximum number of semaphore sets in the entire system.

Minimum - recommended value is 100

All four values are set together using following command.

echo "100 32000 100 100" > /proc/sys/kernel/sem

Asynchronous I/O

To use asynchronous I/O and synchronous I/O, Oracle is relinked with the

following options. The default I/O mode for Oracle is Synchronous I/O.

make -f ins_rdbms.mk async_on

make -f ins_rdbms.mk async_off

If Oracle binary linked with async_on option, then following parameters turn

on/off asynchronous I/O operations.

disk_asynch_io = true (init.ora parameter default)

tape_asynch_io = true (init.ora parameter default)

disk_asynch_io=false (with the Oracle binary linked with async_on, will result in

synchronous I/O)

Asynchronous I/O feature is only available on Red Hat Advanced Server release

and not on other Linux platforms. To get better I/O throughput with DSS

workloads, the /proc/sys/fs/aio-max-size is increased from the default 131072

bytes to >=1M. For OLTP workloads, the default size of 131072 would suffice, as

these workloads perform very small writes.

DNS options

In Red Hat Advanced Server 2.1, the default number of attempts to resolve

hostname is 2. If all the DNS servers listed in /etc/resolv.conf are very busy, the

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Red Hat LINUX ADVANCED SERVER 2.1 - Informations techniques Page 15