禁用」mgmtdb實例致使12c 應用psu失敗

12c安裝集羣的時候會建立一個mgmtdb實例，這個實例是一個單實例，只能運行在一個節點上。我在以前實驗的時候把該實例的內存調到了400m（爲節約系統資源），因爲內存太低，該實例在集羣啓動的時候就不會自動啓動。在節點1實驗打psu的時候，報錯了，日誌以下：
Oracle Clusterware active version on the cluster is [12.2.0.1.0]. The cluster upgrade state is [ROLLING PATCH]. The cluster active patch level is [0].
PRCR-1013 : Failed to start resource ora.mgmtdb


PRCR-1064 : Failed to start resource ora.mgmtdb on node rac01


CRS-5017: The resource action "ora.mgmtdb start" encountered the following error: 


ORA-01078: failure in processing system parameters


. For details refer to "(:CLSN00107:)" in "/u01/app/grid/base/diag/crs/rac01/crs/trace/crsd_oraagent_grid.trc".



CRS-2674: Start of 'ora.mgmtdb' on 'rac01' failed

2017/08/01 16:03:35 CLSRSC-180: An error occurred while executing the command '/u01/app/grid/product/12.2.0/grid/bin/srvctl start mgmtdb -n rac01'
2017/08/01 16:03:35 CLSRSC-490: Starting the Grid Infrastructure Management Repository database failed.

After fixing the cause of failure Run opatchauto resume with session id "RWMS"

此時在grid和oracle用戶下執行./opatch lsinv命令，psu是應用上了的，可是該節點的集羣中止，且手工啓動失敗，查看alert日誌，會看到以下類型的錯誤：
CRS-4123: Starting Oracle High Availability Services-managed resources
CLSU-00105: operating system interface has reported an internal failure
CLSU-00103: error location: canexec2
CLSU-00104: additional error information: no exe permission, file [/u01/app/grid/product/12.2.0/grid/bin/ohasd

CRS-4000: Command Start failed, or completed with errors.
2017/08/01 16:23:00 CLSRSC-117: Failed to start Oracle Clusterware stack

檢查grid用戶的$ORACLE_HOME/bin目錄，集羣啓動須要的相關腳本權限變了，以octssd腳本爲例，正常的owner應該爲root
節點1：
[root@rac01 ~]# ll /u01/app/grid/product/12.2.0/grid/bin/octssd
-rwxr----- 1 grid oinstall 11424 Aug 1 15:57 /u01/app/grid/product/12.2.0/grid/bin/octssd

節點2：
[grid@rac02 ~]$ ll /u01/app/grid/product/12.2.0/grid/bin/octssd
-rwxr----- 1 root oinstall 11424 Jun 29 13:00 /u01/app/grid/product/12.2.0/grid/bin/octssd

這種狀況下須要給這些腳本從新指定owner，此時集羣可以正常啓動。啓動mgmtdb實例，從新應用psu仍是會提示同樣的錯誤。
此時只能回退PSU後再從新應用，回退PSU的過程當中保證數據庫無活動會話。
root用戶下執行回退命令：$GRID_HOME//OPatch/opatchautorollback 26133434/