今天expdp匯出時卡死不跟蹤檔案中出現類似下面的錯誤內容：

WARNING:Could not increase the asynch I/O limit to 3328 for SQL direct I/O. It is set to 128

是oracle的BUG，編號：9949948，只發生在10.2.0.5.0和11.2.0.1.0，解決方法有2種，一種是在作業系統層面修改相關引數另一種方法就是打補丁

MOS上的相關內容為：Warning:Could Not Increase The Asynch I/O Limit To XX For Sql Direct I/O [ID 1302633.1]

In this Document

#SYMPTOM">Symptoms

#CAUSE">Cause

#FIX">Solution

#REF">References

Applies to:

Oracle Server - Enterprise Edition - Version:

10.2.0.5 and

later [Release:

10.2 and later ]

Generic Linux

disk_asynch_io = TRUE

filesystemio_options = none

[root@hnz ~]# cat /proc/sys/fs/aio-max-size

cat: /proc/sys/fs/aio-max-size: No such file or directory

[root@hnz ~]# cat /proc/sys/fs/aio-max-nr

65536

Solution

The aio-max-size kernel parameter doesn't exist in the 2.6.x Linux

kernels.

This feature is now "automatic" in the 2.6.x kernel, based on the

physical capabilities of the disk device driver.

This should mean that the Linux Kernel is ready to perform ASYNC

I/O.

All install requirements should be met.

To ensure ASYNC I/O can be performed by Oracle Database you need to

verify or set the following parameters in the Database:

sql>alter system set disk_asynch_io=true scope=spfile;

sql> alter system set filesystemio_options=setall scope=spfile;

Then shutdown and startup the database and check if the warning

reappears.

An HCVE report (refer to Note 250262.1) should report no remaining

issues

If the above doesn't resolve the problem, then increase

fs.aio-max-nr

References

BUG:10334897 -

COULD NOT INCREASE THE ASYNCH I/O LIMIT TO NNN FOR SQL DIRECT I/O.

IT IS SET TO

BUG:9772888 - WARNING:COULD NOT LOWER THE

ASYNCH I/O LIMIT TO 160 FOR SQL DIRECT I/O. IT IS SE

NOTE:205259.1 - Howto Enable Asynchoronous I/O

on Red Hat Linux 2.1

NOTE:225751.1 - Asynchronous I/O (aio) on

RedHat Advanced Server 2.1 and RedHat Enterprise Linux 3

檢查相關內容，

[oracle@hnz ~]$ sqlplus /as sysdba

SQL*Plus: Release 10.2.0.5.0 - Production on Sat Oct 22

15:57:01 2013

Reserved.

Connected to:

Oracle Database

10g Enterprise Edition Release 10.2.0.5.0 - 64bit

Production

With the Partitioning, OLAP, Data Mining and Real Application

Testing options

SQL> show parameter disk_asynch_io

NAME TYPE VALUE

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

disk_asynch_io boolean TRUE

SQL> show parameter filesystemio_options

NAME TYPE VALUE

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

filesystemio_options string none

SQL>

SQL> alter system set filesystemio_options=setall scope=spfile;

修改核心引數的值：aio-max-nr設定太低，推薦設定為fs.aio-max-nr= 3145728。修改引數使用/sbin/sysctl -p重新載入引數後，重啟資料庫即可

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expdp匯出時卡死 Could not increase the asynch I/O limit to XXX for SQL direct I/O

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