Start CRS even getting “ORA-15040: diskgroup is incomplete” on voting file/OCR diskgroup

Problem:

CRS was down on both nodes, during startup cluster encountered the following error when it was trying to mount diskgroup containing voting files and OCR:

WARNING: Disk Group VOTE containing configured OCR is not mounted
WARNING: Disk Group VOTE containing voting files is not mounted
ORA-15040: diskgroup is incomplete
ORA-15042: ASM disk "0" is missing from group number "1" 

The diskgroup, where OCR and voting files were located was not able to mount because one disk was missing. As a result CRS is down:

# crsctl status res -t
CRS-4535: Cannot communicate with Cluster Ready Services
CRS-4000: Command Status failed, or completed with errors.

We know that NORMAL redundancy diskgroup can tolerate one mirror problem at a time.

Solution:

1. Start HAS and check status of the local resoureces

# crsctl start has

# crsctl status res -t -init

---------------------------------------------------------------------------
Name          Target      State        Server      State details       
---------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------- 
ora.asm
       1       ONLINE      ONLINE       rac2         STABLE
 ora.cluster_interconnect.haip
       1        ONLINE     ONLINE       rac2         STABLE
 ora.crf
       1        OFFLINE    OFFLINE                   STABLE
 ora.crsd
       1        ONLINE      OFFLINE                  STABLE
 ora.cssd
       1        ONLINE      ONLINE       rac2        STABLE
 ora.cssdmonitor
       1        ONLINE      ONLINE       rac2        STABLE
 ora.ctssd
       1        ONLINE      ONLINE       rac2        OBSERVER,STABLE
 ora.diskmon
       1        OFFLINE      OFFLINE                 STABLE
 ora.drivers.acfs
       1        ONLINE      ONLINE       rac2        STABLE
 ora.evmd
       1        ONLINE      INTERMEDIATE rac2        STABLE
 ora.gipcd
       1        ONLINE      ONLINE       rac2        STABLE
 ora.gpnpd
       1        ONLINE      ONLINE       rac2        STABLE
 ora.mdnsd
       1        ONLINE      ONLINE       rac2        STABLE
 ora.storage
       1        ONLINE      OFFLINE      rac2        STABLE 

2. Connect to the ASM instance and mount diskgroup using force option.

ASM instance will be in nomount state, because diskgroup having voting files and OCR cannot be mounted.

Force option is mandatory, otherwise you will get the same ORA-15040 error.

# su - grid

$ sqlplus / as sysasm

SQL*Plus: Release 12.2.0.1.0 Production on Tue May 28 16:14:14 2019
Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Connected to:
 Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

SQL> alter diskgroup VOTE mount force;
Diskgroup altered.

This operation sometimes takes ~6min to complete because of the following notification in alert_ASM?.log

"WARNING: Background operations delayed until 05/28/19 16:19:47 because ASM was not stopped cleanly and there could be disconnected client(s)"

The error message is self explanatory.

3. The diskgroup online operation on the 2nd step should trigger clusterware autostart, if not start it using the following command:

# crsctl start cluster

4. Check CRS status:

# crsctl status res -t 

---------------------------------------------------------------------------
Name           Target  State        Server       State details       
--------------------------------------------------------------------------- 
Local Resources

ora.ASMNET1LSNR_ASM.lsnr
                ONLINE  ONLINE       rac2        STABLE
ora.DATA.dg
                ONLINE  OFFLINE      rac2        STABLE
ora.FRA.dg
                ONLINE  OFFLINE      rac2        STABLE
ora.LISTENER.lsnr
                ONLINE  ONLINE       rac2        STABLE
ora.MGMT.dg
                ONLINE  OFFLINE      rac2        STABLE
ora.VOTE.dg
                ONLINE  ONLINE       rac2        STABLE
ora.chad
                ONLINE  OFFLINE      rac2        STABLE
ora.net1.network
                ONLINE  ONLINE       rac2        STABLE
ora.ons
                ONLINE  ONLINE       rac2        STABLE
ora.proxy_advm
                OFFLINE OFFLINE      rac2        STABLE
---------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------- 
ora.LISTENER_SCAN1.lsnr
       1        ONLINE  ONLINE       rac2        STABLE
 ora.LISTENER_SCAN2.lsnr
       1        ONLINE  ONLINE       rac2        STABLE
 ora.LISTENER_SCAN3.lsnr
       1        ONLINE  ONLINE       rac2        STABLE
 ora.MGMTLSNR
       1        OFFLINE OFFLINE                  STABLE
 ora.asm
       1        ONLINE  OFFLINE                  STABLE
       2        ONLINE  ONLINE       rac2        Started,STABLE
 ora.cvu
       1        ONLINE  ONLINE       rac2        STABLE
 ora.mgmtdb
       1        OFFLINE OFFLINE                  STABLE
 ora.qosmserver
       1        ONLINE  ONLINE       rac2        STABLE 
 ora.rac1.vip
       1        ONLINE  INTERMEDIATE rac2        FAILED OVER,STABLE
 ora.rac2.vip
       1        ONLINE  ONLINE       rac2        STABLE
 ora.scan1.vip
       1        ONLINE  ONLINE       rac2        STABLE
 ora.scan2.vip
       1        ONLINE  ONLINE       rac2        STABLE
 ora.scan3.vip
       1        ONLINE  ONLINE       rac2        STABLE

Recommendation:

Change corrupted disks as soon as possible and make it online.

How to delete MGMTDB?

Introduction

MGMTDB is a repository database that saves Cluster Health Monitor (CHM) data. In Oracle 11g this information was stored in Berkley database ( .bdb files) but starting from Oracle database 12c it is configured as an Oracle single instance database.

In Oracle 12.1.0.1 – GIMR is optional. Whereas in Oracle 12.1.0.2 – it’s mandatory  and it’s not supported to be turned off with the exception of Exadata.
I’ve searched a lot to find out why it is not supported to be turned off, but I still do not have that answer. I only know that TFA collects some information from MGMTDB and if we turn it off, it means TFA will not be able to retrieve that information. In 19c GIMR is optional again.

The reason why I want to turn it off, is that there are several bugs related to MGMTDB. We have noticed that several customers had performance related issues because of MGMTDB. The repository database was able to use almost 100% of CPU resources. In addition to this, one customer noticed that MGMTDB increased up to 60GB and exhausted GRID diskgroup where OCR and voting files were located (this size is not normal for 3-node cluster).

More information about Grid Infrastructure Management Repository (GIMR) can be found at 1568402.1

Steps

Please consider that for 12.1.0.2 deleting it is not supported by Oracle, which is not clear why, but it is better to ask Oracle support before doing this.

Instead of deleting a repository, it is better to apply all bug fixes that is related to it. And try to use it’s intelligece to proactively tune your database. But if you still want to delete it, or at least know how to delete it – then let’s do that, it is not harmful.

1. Stop and disable CRF

# crsctl stop res ora.crf -init
CRS-2673: Attempting to stop 'ora.crf' on 'rac1'
CRS-2677: Stop of 'ora.crf' on 'rac1' succeeded 

# crsctl modify res ora.crf -attr ENABLED=0 -init

# crsctl status res ora.crf -init
NAME=ora.crf
TYPE=ora.crf.type
TARGET=OFFLINE
STATE=OFFLINE 

2. Delete MGMTDB using dbca

Database must be up and running to do this step.

# su - grid

$ dbca -silent -deleteDatabase -sourceDB -MGMTDB
Connecting to database
4% complete
9% complete
14% complete
19% complete
23% complete
28% complete
47% complete
Updating network configuration files
52% complete
Deleting instance and datafiles
76% complete
100% complete    

3. Make sure that MGMTDB was deleted

# srvctl status mgmtdb
PRCD-1120 : The resource for database _mgmtdb could not be found.
PRCR-1001 : Resource ora.mgmtdb does not exist

Diagnostic Tools Catalog (Doc ID 559339.1)

I want to share information about the document Doc ID 559339.1. The mentioned document contains links to very useful Diagnostics Tools for Database (as well as for Fusion Middleware and E-Business Suite)

Recently I used ORA-4031-Troubleshooting Tool, uploaded database TFA log and got very informative recommendation. My shared pool was fragmented and did not have large enough chunk of memory to satisfy memory requests. Based on this information we decided to increase shared_pool size.