Hi everyone,
Today in this article I would like to share my experience regarding drop/recreate the MGMTDB in order to purge the repository and free some space from ASM Disk Group.

I was going to perform a migration from Oracle Database 12.2 Single Instance to an Oracle Database 12.2 Rac One Node, when I found something bizarre. The “+DATA” diskgroup was 59GB of used space and it was a fresh installation (Only few weeks waiting for the “GO” to migrate without any database).

After performing the actions below, I was able free / to get back about 20GB.

Documents used in this procedure:

  • How to Move/Recreate GI Management Repository (GIMR / MGMTDB) to Different Shared Storage (Diskgroup, CFS or NFS etc) (Doc ID 1589394.1)
  • 12.2: How to Create GI Management Repository (Doc ID 2246123.1)
  • MDBUtil: GI Management Repository configuration tool (Doc ID 2065175.1)

Steps:

[oracle@lab-dev-datad1 ~]
$ . oraenv
 ORACLE_SID = [+ASM1] ? +ASM1
 The Oracle base remains unchanged with value /u01/base
[oracle@lab-dev-datad1 ~]
$ ps -ef | grep pmon
 oracle   19280     1  0 08:21 ?        00:00:00 asm_pmon_+ASM1
 oracle   21769     1  0 08:21 ?        00:00:00 mdb_pmon_-MGMTDB
 oracle   22655 29118  0 11:05 pts/1    00:00:00 grep --color=auto pmon
[oracle@lab-dev-datad1 ~]$ asmcmd lsdg
[oracle@lab-dev-datad1 ~]
$ asmcmd -p
ASMCMD [+] > ls -l

State    Type    Rebal  Name

MOUNTED  EXTERN  N      DATA/

MOUNTED  EXTERN  N      FRA/

ASMCMD [+] >
ASMCMD [+] > du FRA

Used_MB      Mirror_used_MB

   2268                2268
ASMCMD [+] > du DATA

Used_MB      Mirror_used_MB

  59292               59292
ASMCMD [+] > cd DATA
ASMCMD [+DATA] > ls -l

Type      Redund  Striped  Time             Sys  Name

                                            Y    ASM/

                                            N    _mgmtdb/

                                            Y    dev-data-clu/

PASSWORD  UNPROT  COARSE   JUL 09 16:00:00  N    orapwasm => +DATA/ASM/PASSWORD/pwdasm.256.1013185265

PASSWORD  UNPROT  COARSE   JUL 09 16:00:00  N    orapwasm_backup => +DATA/ASM/PASSWORD/pwdasm.257.1013185629
ASMCMD [+DATA] > du ASM

Used_MB      Mirror_used_MB

      0                   0
ASMCMD [+DATA] > du _mgmtdb/

Used_MB      Mirror_used_MB

  57776               57776

Stopping required resources in both nodes:

As root user, from Grid Home:

[root@lab-dev-datad1 ~]# /u01/oracle/base/product/12.2.0/grid/bin/crsctl stop res ora.crf -init
 CRS-2673: Attempting to stop 'ora.crf' on 'lab-dev-datad1'
 CRS-2677: Stop of 'ora.crf' on 'lab-dev-datad1' succeeded
[root@lab-dev-datad2 ~]# /u01/oracle/base/product/12.2.0/grid/bin/crsctl stop res ora.crf -init
 CRS-2673: Attempting to stop 'ora.crf' on 'lab-dev-datad2'
 CRS-2677: Stop of 'ora.crf' on 'lab-dev-datad2' succeeded
[root@lab-dev-datad1 ~]# /u01/oracle/base/product/12.2.0/grid/bin/crsctl modify res ora.crf -attr ENABLED=0 -init 
[root@lab-dev-datad2 ~]# /u01/oracle/base/product/12.2.0/grid/bin/crsctl modify res ora.crf -attr ENABLED=0 -init

Validate MGMTDB database status:

[root@lab-dev-datad1 ~]# /u01/oracle/base/product/12.2.0/grid/bin/srvctl status mgmtdb
 Database is enabled
 Instance -MGMTDB is running on node lab-dev-datad1

Deleting MGMTDB using DBCA in silent mode:

As oracle user:

[oracle@lab-dev-datad1 ~]$ /u01/oracle/base/product/12.2.0/grid/bin/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
 Look at the log file "/u01/base/cfgtoollogs/dbca/_mgmtdb.log" for further details.

Validate the current space from “+DATA” diskgroup:

[oracle@lab-dev-datad1 ~]$ asmcmd lsdg

In order to recreate the MGMTDB in Oracle Database 12/R2 (12.2), is required to use a perl script (mdbutil.pl), that you can download from here:

  • MDBUtil: GI Management Repository configuration tool (Doc ID 2065175.1)

Recreating MGMTDB:

Listing options:

[oracle@lab-dev-datad1 ~]$ ./mdbutil.pl -h
 Usage:
      Create/Enable MGMTDB & CHM
        mdbutil.pl --addmdb --target=
      Move MGMTDB to another location
        mdbutil.pl --mvmgmtdb --target=
      Check MGMTDB status
        mdbutil.pl --status
mdbutil.pl OPTIONS
    --addmdb            Create MGMTDB/CHM and reconfigure related functions
    --mvmgmtdb          Migrate MGMTDB to another location
    --target='+DATA'    MGMTDB Disk Group location
    --status            Check the CHM & MGMTDB status
    --help              Display this help and exit
    --debug             Verbose commands output/trace
Example:
    Create/Enable MGMTDB:
      mdbutil.pl --addmdb --target=+DATA
    Move MGMTDB to another location:
      mdbutil.pl --mvmgmtdb --target=+REDO
    Check CHM:
      mdbutil.pl --status

Launch MGMTDB creation:

[oracle@lab-dev-datad1 ~]$ ./mdbutil.pl --addmdb --target=+DATA
mdbutil.pl version : 1.98
 2019-10-04 11:32:18: I Starting To Configure MGMTDB at +DATA…
 2019-10-04 11:32:21: I Container database creation in progress… for GI 12.2.0.1.0
 2019-10-04 11:42:13: I Plugable database creation in progress…
 2019-10-04 11:47:20: I Executing "/tmp/mdbutil.pl --addchm" on lab-dev-datad1 as root to configure CHM.
 root@lab-dev-datad1's password:
 2019-10-04 11:49:50: I MGMTDB & CHM configuration done!
 root@lab-dev-datad2's password:
 2019-10-04 11:49:50: I MGMTDB & CHM configuration done!

Modifying back the resource ora.crf in both nodes:

As root user, from Grid Home:

[root@lab-dev-datad1 ~]# /u01/oracle/base/product/12.2.0/grid/bin/crsctl modify res ora.crf -attr ENABLED=1 -init
[root@lab-dev-datad1 ~]# /u01/oracle/base/product/12.2.0/grid/bin/crsctl start res ora.crf -init
 CRS-2672: Attempting to start 'ora.crf' on 'lab-dev-datad1'
 CRS-2676: Start of 'ora.crf' on 'lab-dev-datad1' succeeded
[root@lab-dev-datad2 ~]# /u01/oracle/base/product/12.2.0/grid/bin/crsctl modify res ora.crf -attr ENABLED=1 -init
[root@lab-dev-datad2 ~]# /u01/oracle/base/product/12.2.0/grid/bin/crsctl start res ora.crf -init
 CRS-2672: Attempting to start 'ora.crf' on 'lab-dev-datad2'
 CRS-2676: Start of 'ora.crf' on 'lab-dev-datad2' succeeded
[oracle@lab-dev-datad1 ~]$ /u01/oracle/base/product/12.2.0/grid/bin/srvctl status mgmtdb
 Database is enabled
 Instance -MGMTDB is running on node lab-dev-datad1

Validate the current size after MGMTDB database creation:

[oracle@lab-dev-datad1 ~]$ asmcmd lsdg
[oracle@lab-dev-datad1 ~]$ asmcmd -p 
ASMCMD [+] > ls -l

State    Type    Rebal  Name

MOUNTED  EXTERN  N      DATA/

MOUNTED  EXTERN  N      FRA/
ASMCMD [+] > du DATA Used_MB      Mirror_used_MB   34256               34256

From Oracle 12.2 Standalone Cluster is required at least 37.6GB only for MGMTDB

Oracle Clusterware Storage Space Requirements (12.2)

  • Table 8-5 Mininum Space Requirements for Oracle Standalone Cluster

PS: FAQ: 12c Grid Infrastructure Management Repository (GIMR) (Doc ID 1568402.1)

See you in the next post!