/dev/async, /etc/privgroup ????

[곽수희]

OPS 사용시 /dev/async, /etc/privgroup 를 설정해 줘야한다고

알고 있습니다.

하지만, 이것들의 기능 및 설정하지 않았을 경우의

문제점에 대해서 좀 더 자세하게 알고 싶습니다.

[고광태]

MLOCK 은 그룹에 할당되어질수있는 권한입니다. 이권한을 가진 그룹의 유저들은 메모리안의 텍스트 그리고 데이타 그리고 공유메모리세그먼트 를 lock 할수있습니다. 이것은 여러 오라클 인스턴스들을 돌리는데 꼭 필요합니다.



시스템의 현재 권한을 보기위해서는

#getprivgrp

현재 셋팅을 보실수있습니다.



/dev/async 는 오라클에서 비동적으로 io 를 사용하려고 할때 사용되는 드라이버입니다.



DISK_ASYNC_IO =true in your init.ora file .

오라클파일에서 사용하려고 한다면 위의 설정을 해야합니다.



오라클의성능을 위해서 사용되는것입니다.



참조하시길..

[김태경]

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Doc ID:

Note:218027.1

Subject: HP SCHED_NOAGE Scheduling Policy to improve Performance for Oracle

Type: BULLETIN

Status: PUBLISHED

Content Type: TEXT/PLAIN

Creation Date: 09-NOV-2002

Last Revision Date: 03-MAR-2003



Purpose

-------



To provide Information on time sharing scheduling policy on HP and how Oracle

makes use of the SCHED_NOAGE scheduling policy.



SCOPE & APPLICATION

-------------------



This note is intended for DBAs/ UNIX Admin to improve performance in OLTP.





HP SCHED_NOAGE Scheduling Policy

--------------------------------

On HP, most processes use a time sharing scheduling policy. Time sharing can

have detrimental effects on Oracle performance by descheduling an Oracle process

during critical operations, for example, holding a latch. HP has a

modified scheduling policy, referred to as SCHED_NOAGE, that specifically

addresses this issue. Unlike the normal time sharing policy, a process scheduled

using SCHED_NOAGE does not increase or decrease in priority, nor is it preempted.



This feature is suited to online transaction processing (OLTP) environments

because OLTP environments can cause competition for critical resources.

In laboratory tests, the use of the SCHED_NOAGE policy with Oracle9i increased

performance by up to 10 percent in OLTP environments. The SCHED_NOAGE policy

creates little or no gains in decision support (DSS) Environments because

there is little resource competition in these environments. Because each

application and server environment is different, you should test and verify

whether your environment benefits from the SCHED_NOAGE policy.





Enabling SCHED_NOAGE for Oracle

-------------------------------





To allow Oracle to use the SCHED_NOAGE scheduling policy, the group that the

Oracle software owner belongs to (dba), must have the RTSCHED and RTPRIO

privileges to change the scheduling policy and set the priority level for Oracle

processes.





To give the dba group these privileges:



1.As the root user, enter the following command:



# setprivgrp dba RTSCHED RTPRIO





2.To retain these privileges after rebooting, create the /etc/privgroup file, if

it does not exist on your system, and add the following line to it:



dba RTSCHED RTPRIO



___________________________________________________________________

Note:

Please remember to set the MLOCK privilege as well when using

raw devices.

___________________________________________________________________



3. The Oracle DBA must add the parameter HPUX_SCHED_NOAGE to the INIT.ORA file

to enable the scheduling policy. HPUX_SCHED_NOAGE takes an integer parameter,

and for HPUX 11.0 the valid ranges are 154 to 255; for HPUX 11i, the valid

ranges are 178 to 255. Higher priorities are represented by lower values.



hpux_sched_noage=154 (for HP/UX 11.0)

hpux_sched_noage=178 (for HP/UX 11i)



Overall performance improvements of 5 to 10% especially for OLTP applications

can be expected.



References:

The HP documentation, rtsched(1) and rtsched(2) man page for more information

on priority policies and priority ranges.

.

________________________________________



Copyright (c) 1995,2000 Oracle Corporation. All Rights Reserved. Legal Notices and Terms of Use.

[Jongmin, Lee]

안녕하세요~

이종민입니다.



/dev/async, /etc/privgroup 는 async IO mode를 위한 설정일 뿐, OPS를 사용한다고 반드시 async IO mode를 구성하는것은 아닙니다.



async IO mode는 raw device를 사용하시는 경우, 성능 향상을 위한 oracle의 권장사항입니다.

OPS는 반드시 raw device를 사용하시므로, async IO mode가 권장되겠지요..

OPS 자체가 확연한 성능감소를 가져오므로, async IO mode를 설정하시는 것은 필요하다고 볼수 있습니다.



HPUX 11.x & oracle8i 에서의 async IO mode구성법을 첨부하겠습니다.



그럼~