解决在RHEL/CentOS7.4以上版本无法使用AFD(Oracle ASMFD)特性

在7.4以上的redhat或者centos，配置afd不能配置成功，AFD is not ‘supported’，经过查询MOS资料，发现在7.4以上的redhat内核需要升级”kmod”

1、加载afd

[root@rac1 ~]# asmcmd afd_configure
ASMCMD-9520: AFD is not 'supported' -----仅输出不支持的信息，无法得知具体内容

2、查看afd的支持的内核版本

[root@rac1 ~]# afdroot install
AFD-620: AFD is not supported on this operating system version: '3.10.0-693.el7.x86_64'

[root@rac1 ~]#  acfsdriverstate -orahome $ORACLE_HOME supported
ACFS-9459: ADVM/ACFS is not supported on this OS version: '3.10.0-693.el7.x86_64'
ACFS-9201: Not Supported 


[root@rac1 ~]# uname -a       
Linux rac1 3.10.0-693.el7.x86_64 #1 SMP Thu Jul 6 19:56:57 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux
----查看当前系统内核版本确实不被支持

[root@rac1 ~]# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 7.4 (Maipo)

3、查看kmod版本

[root@rac2 ~]# rpm -qa|grep kmod
kmod-libs-20-15.el7.x86_64
kmod-20-15.el7.x86_64   ----20-15版本

4、升级kmod

[root@rac1 yum.repos.d]# yum install kmod
Loaded plugins: langpacks, product-id, search-disabled-repos, subscription-manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
Local                                                                                           | 3.6 kB  00:00:00     
(1/2): Local/group_gz                                                                           | 166 kB  00:00:00     
(2/2): Local/primary_db                                                                         | 3.1 MB  00:00:00     
Resolving Dependencies
--> Running transaction check
---> Package kmod.x86_64 0:20-15.el7 will be updated
---> Package kmod.x86_64 0:20-21.el7 will be an update
--> Finished Dependency Resolution

Dependencies Resolved

=======================================================================================================================
 Package                   Arch                        Version                        Repository                  Size
=======================================================================================================================
Updating:
 kmod                      x86_64                      20-21.el7                      Local                      121 k

Transaction Summary
=======================================================================================================================
Upgrade  1 Package

Total download size: 121 k
Is this ok [y/d/N]: y
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Warning: RPMDB altered outside of yum.
  Updating   : kmod-20-21.el7.x86_64                                                                               1/2 
  Cleanup    : kmod-20-15.el7.x86_64                                                                               2/2 
  Verifying  : kmod-20-21.el7.x86_64                                                                               1/2 
  Verifying  : kmod-20-15.el7.x86_64                                                                               2/2 

Updated:
  kmod.x86_64 0:20-21.el7                                                                                              

Complete!

5、再次查看lmod

[grid@rac1:/home/grid]$rpm -qa|grep kmod
kmod-libs-20-15.el7.x86_64
kmod-20-21.el7.x86_64  --->已升级到20-21版本

6、查看afd驱动信息

[root@rac1 yum.repos.d]#  acfsdriverstate -orahome $ORACLE_HOME supported
ACFS-9200: Supported 升级kmod之后afd驱动已支持

7、重新安装afd
加载以及配置AFD

[root@rac1 yum.repos.d]# asmcmd afd_configure

加载afd过程：

AFD-627: AFD distribution files found.
AFD-634: Removing previous AFD installation.
AFD-635: Previous AFD components successfully removed.
AFD-636: Installing requested AFD software.
AFD-637: Loading installed AFD drivers.
AFD-9321: Creating udev for AFD.
AFD-9323: Creating module dependencies - this may take some time.
AFD-9154: Loading 'oracleafd.ko' driver.
AFD-649: Verifying AFD devices.
AFD-9156: Detecting control device '/dev/oracleafd/admin'.
AFD-638: AFD installation correctness verified.
Modifying resource dependencies - this may take some time.

查询afd状态信息

[root@rac1 yum.repos.d]# asmcmd afd_state
ASMCMD-9526: The AFD state is 'LOADED' and filtering is 'ENABLED' on host 'rac1'

无任何报错，配置成功

MOS id:2303388.1

ACFS and AFD report “Not Supported” after installing appropriate Oracle Grid Infrastructure Patches on RedHat (文档 ID 2303388.1)

了解KMOD

https://www.linux.org/docs/man8/kmod.html
上述为linux对kmod的一段简单描述，简单意思是KMOD是管理linux内核的一个模块，对于用户来说不会直接使用kmod，而是其他一些系统命令会调用。
进入sbin目录发现kmod被做了软连接，很多系统命令会被重定向

[grid@rac1:/sbin]$pwd
/sbin
[grid@rac1:/sbin]$ls -alt | grep kmod
lrwxrwxrwx   1 root root           11 Feb 15 17:11 insmod -> ../bin/kmod
lrwxrwxrwx   1 root root           11 Feb 15 17:11 lsmod -> ../bin/kmod
lrwxrwxrwx   1 root root           11 Feb 15 17:11 modinfo -> ../bin/kmod
lrwxrwxrwx   1 root root           11 Feb 15 17:11 modprobe -> ../bin/kmod
lrwxrwxrwx   1 root root           11 Feb 15 17:11 rmmod -> ../bin/kmod
lrwxrwxrwx   1 root root           11 Feb 15 17:11 depmod -> ../bin/kmod