最近的alert日志中碰到了ora-27090的错误信息，其错误提示为unable to reserve kernel resources for asynchronous disk i/o。根
最近的alert日志中碰到了ora-27090的错误信息，其错误提示为unable to reserve kernel resources for asynchronous disk i/o。根据这个提示来看是跟异步i/o相关的内核参数问题。下面是这个问题的描述与解决。
1、故障错误信息
wed sep 10 09:58:17 cst 2014
errors in file /u01/app/oracle/admin/orclls/bdump/orclls_p000_47020.trc:
ora-27090: unable to reserve kernel resources for asynchronous disk i/o
linux-x86_64 error: 2: no such file or directory
additional information: 3
additional information: 128
additional information: 65536
wed sep 10 09:58:17 cst 2014
errors in file /u01/app/oracle/admin/orclls/bdump/orclls_p002_47024.trc:
ora-27090: unable to reserve kernel resources for asynchronous disk i/o
linux-x86_64 error: 2: no such file or directory
additional information: 3
additional information: 128
additional information: 65536
2、故障分析
#调用oerr，没有获得比较有价值的信息，，如下：
suse11b:oracle:orcl102 > oerr ora 27090
27090, 00000, unable to reserve kernel resources for asynchronous disk i/o
// *cause: the system call to reserve kernel resources for asynchronous i/o
// has failed.
// *action: check errno
#进一步查看trace文件，注，当前数据库版本为10.2.0.5，os为suse 11 sp3
suse11a:oracle:orcl101 > more /u01/app/oracle/admin/orclls/bdump/orclls_p002_47024.trc
/u01/app/oracle/admin/orclls/bdump/orclls_p002_47024.trc
oracle database 10g enterprise edition release 10.2.0.5.0 - 64bit production
with the partitioning, real application clusters, olap, data mining
and real application testing options
oracle_home = /u01/app/oracle/product/10.2/db_1
system name: linux
node name: suse11a
release: 3.0.76-0.11-default
version: #1 smp fri jun 14 08:21:43 utc 2013 (ccab990)
machine: x86_64
instance name: orclls
redo thread mounted by this instance: 1
oracle process number: 35
unix process pid: 47024, image: oracle@suse11a (p002)
*** service name:() 2014-09-10 09:58:17.159
*** session id:(1072.1) 2014-09-10 09:58:17.159
*** 2014-09-10 09:58:17.159
kcrp: blocks claimed = 0, eliminated = 0
----- recovery hash table statistics ---------
hash table buckets = 32768
longest hash chain = 0
average hash chain = 0/0 = 0.0
max compares per lookup = 0
avg compares per lookup = 0/0 = 0.0
----------------------------------------------
ora-27090: unable to reserve kernel resources for asynchronous disk i/o
linux-x86_64 error: 2: no such file or directory
additional information: 3
additional information: 128
additional information: 65536
----- recovery hash table statistics ---------
hash table buckets = 32768
longest hash chain = 0
average hash chain = 0/0 = 0.0
max compares per lookup = 0
avg compares per lookup = 0/0 = 0.0
----------------------------------------------
#从trace文件中也没有获得比较有价值的信息
3、故障解决
#根据ora-27090: message 27090 not found; (文档 id 579108.1)文档，我们修改内核参数fs.aio-max-nr
#由于此数据库为rac环境下，因此同时调整了2个节点，以下为调整后的情形。
suse11a:~ # grep max-nr /etc/sysctl.conf
#fs.aio-max-nr = 1048576
fs.aio-max-nr = 3145728
suse11b:~ # grep max-nr /etc/sysctl.conf
#aio-max-nr = 1048576
fs.aio-max-nr = 3145728
suse11a:~ # sysctl -p
suse11b:~ # sysctl -p
#配置完毕后可以通过cluvy校验
#几日后观察alert日志，未发现该类错误。
check: kernel parameter for aio-max-nr
node name current configured required status comment
---------------- ------------ ------------ ------------ ------------ ------------
suse11a 3145728 3145728 1048576 passed
suse11b 3145728 3145728 1048576 passed
result: kernel parameter check passed for aio-max-nr
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