ORACLE RAC环境记的之前GI和DB的version 前4位相同是可以兼容的，甚至有时DB PSU比GI PSU新，最近有朋友遇到只安装了DB PSU后，RAC中实例启动失败的问题，这里记录一下原因。
1, Check db alert log
[USER(3037)]CRS-2316:Fatal error: cannot initialize GPnP, CLSGPNP_ERR (Generic GPnP error).
kggpnpInit: failed to init gpnp
WARNING: No cluster interconnect has been specified. Depending on
the communication driver configured Oracle cluster traffic
may be directed to the public interface of this machine.
Oracle recommends that RAC clustered databases be configured
with a private interconnect for enhanced security and
performance.
2, Check interconnect network
Public interface used as interconnect interface as seen in gv$cluster_interconnects
Cause
For a database instance running in a RAC cluster, both DB PSU component and OCW PSU component of the GI PSU must be applied.
In this case, only the DB PSU component was applied to the DB home without applying the OCW PSU component of the GI PSU.
Verify using “opatch lsniventory” command on the database home.
From October 2018 PSU of Oracle RAC you must apply OCW component of the GI patch as well to the Oracle Home.
OCW Patch is available as part of GI PSU Bundle, you cannot download it individually (in general),But you can apply it individually to DB Home. This can be really an issue if you have done newer versions of Oracle install on higher version of Cluster.
Solution – Apply OCW Patch
$<UNZIPPED_PATCH_LOCATION>/<patch>/custom/server/<patch>/custom/scripts/prepatch.sh -dbhome <ORACLE_HOME>
$<ORACLE_HOME>/OPatch/opatch napply -oh <ORACLE_HOME> -local <UNZIPPED_PATCH_LOCATION>/<patch>/custom/server/<patch>
$<UNZIPPED_PATCH_LOCATION>/<patch>/custom/server/<patch>/custom/scripts/postpatch.sh -dbhome <ORACLE_HOME>