最近在现场维护数据库(Windows Server 2008 R2+Oracle 10.2.0.5)时，发现数据库软件所在分区的空间几乎所剩无几。
将近100G的空间，除了操作系统和数据库软件，其余什么都没有安装，竟然只有6.15G可用，这是怎么回事呢？

依次排查C盘下的目录，发现问题出在了bdmp目录。
不看不知道，一看吓一跳，超过2G的trace文件有9个，其中有一个将近10G；
其余将近1G的还有不少，怪不得只有6.15G可用空间呢。

那么，这些trace文件都记录了什么内容呢？选了几个KB、MB级别的文件打开看了一下，发现内容都一样：
点击(此处)折叠或打开

Dump file c:\oracle\product\10.2.0\admin\HOEGH\bdump\HOEGH_s009_6048.trc
Sat Jul 30 01:07:40 2016
ORACLE V10.2.0.5.0 - 64bit Production vsnsta=0
vsnsql=14 vsnxtr=3
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Windows NT Version V6.1 Service Pack 1
CPU : 40 - type 8664, 20 Physical Cores
Process Affinity : 0x0000000000000000
Memory (Avail/Total): Ph:11348M/32757M, Ph+PgF:43306M/65513M
Instance name: HOEGH
Redo thread mounted by this instance: 1
Oracle process number: 28
Windows thread id: 6048, image: ORACLE.EXE (S009)
*** 2016-07-30 01:07:40.094
*** SESSION ID:(291.400) 2016-07-30 01:07:40.079
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** SESSION ID:(168.4402) 2016-07-30 01:07:41.295
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** 2016-07-30 01:07:53.978
*** SESSION ID:(205.686) 2016-07-30 01:07:53.978
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** SESSION ID:(224.27814) 2016-07-30 01:07:55.195
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** 2016-07-30 01:09:37.079
*** SESSION ID:(241.21749) 2016-07-30 01:09:37.079
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** 2016-07-30 01:13:37.179
*** SESSION ID:(298.53285) 2016-07-30 01:13:37.179
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** 2016-07-30 01:14:07.427
*** SESSION ID:(219.44573) 2016-07-30 01:14:07.427
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** SESSION ID:(263.59334) 2016-07-30 01:14:08.691
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** 2016-07-30 01:20:09.130
*** SESSION ID:(160.19644) 2016-07-30 01:20:09.130
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** SESSION ID:(280.35874) 2016-07-30 01:20:10.346
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1
*** 2016-07-30 01:21:52.277
*** SESSION ID:(224.27814) 2016-07-30 01:21:52.277
WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O. It is set to -1

通过查找资料得知，这是WARNING是个Bug，和Oracle的特定版本有关：
点击(此处)折叠或打开

'Warning:Could not Lower the Asynch I/O Limit to 224 for SQL direct I/O. It is set to -1' After Upgrading To 10.2.0.5 (Doc ID 1155445.1)
Bug 9772888 - Needless "WARNING:Could not lower the asynch I/O limit to .. for SQL direct I/O It is set to

该Bug 影响的2个版本：

10.2.0.5

11.2.0.1

在如下版本已经修复：

12.1 (Future Release)

11.2.0.2 (Server Patch Set)

10.2.0.5.2 Patch Set Update

10.2.0.5 Patch 1 on Windows Platforms

那么，如何解决这个bug呢？
貌似只能升级到上述修复版本或者更高版本。

回想当初，我们由10.2.0.4升级到10.2.0.5，只是为了解决Oracle在Rose HA环境下EM无法正常工作的问题（事实上只是解决了一个其中一个小bug，EM在双机切换时仍然无法正常使用）。
没想到，却引入了这么一个bug。

重要的事情说三遍：
升级需谨慎！
升级需谨慎！
升级需谨慎！

~~~~~~~ the end~~~~~~~~~
hoegh
2016.08.03

ITPub博客

WARNING:Could not lower the asynch I/O limit to 160 for SQL direct I/O.

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