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/Dev/Async Traces After Upgrade To 10gR2 On HP-UX PA-RISC [ID 382674.1]

原创 Linux操作系统 作者:alsrt 时间:2011-06-05 09:43:40 0 删除 编辑

/Dev/Async Traces After Upgrade To 10gR2 On HP-UX PA-RISC [ID 382674.1]


修改时间 19-NOV-2010 类型 PROBLEM 状态 MODERATED


In this Document

Platforms: 1-914CU;

This document is being delivered to you via Oracle Support's Rapid Visibility (RaV) process and therefore has not been subject to an independent technical review.

Applies to:

Oracle Server - Enterprise Edition - Version: to - Release: 10.2 to 10.2
Information in this document applies to any platform.
***Checked for relevance on 19-Nov-2010***


After migration to Oracle RDBMS 10gR2 on HP-UX, trace files are being generated with the following content:

File '/dev/async' not present : errno=2


To start diagnosing the issue, you should refer the following document to find out if you are at all using async IO:

Note 139272.1 HP-UX: Asynchronous I/O

If you are using async IO and still the problem appears, then you need to check if the device '/dev/async' exists or not. Consult your SA (System Administrator) on how to troubleshoot the same.

Else, you need to ensure that the database does not start up with IO parameters.

Note that async is usually an option for improved performance, but if the filesystem/disk hardware does not support this then you should refrain from using the same.


You have the following 2 options here:

1. Create '/dev/async' to suppress these errors. To create '/dev/async', you need to do the following as root:

/sbin/mknod /dev/async c 101 0x0
/usr/bin/chown oracle:dba /dev/async
/usr/bin/chmod 000 /dev/async

The permissions on /dev/async of 000 ensure that it is not possible to use the async driver unintentionally.


2. Disable async at the database level. You should set the following parameters as follows:

disk_asynch_io = FALSE
filesystemio_options =

may be any of the following:
"asynch" - Set by default. This allows asynchronous IO to be used where supported by the OS.
"directIO" - This allows directIO to be used where supported by the OS. Direct IO bypasses any
Unix buffer cache.
"setall" - Enables both ASYNC and DIRECT IO.
"none" - This disables ASYNC IO and DIRECT IO so that Oracle uses normal synchronous writes, without any direct io options.

You should consult your SA to find out supported option and select that.

However, this parameter should not normally be set by the user. It is mainly here to help avoid OS
bugs / problems by disabling certain types of IO. You should modify this ONLY if you had this set earlier. Otherwise, just setting disk_asynch_io should be okay.


NOTE:60692.1 - ALERT:HP-UX: Tracefiles reference /dev/async when async i/o not configured



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