Since -MGMT DB uses OCR/Voting disk by default, It is strongly recommended to check MGMT database tablespace usage. In some GI versions, we see MGMT database used all OCR/Voting disk.
What is Management Repository?
Grid Infrastructure Management Repository ( GIMR ) is a single instance database managed by GI. It will be up and running on one node in the cluster. If the hosting node is down, the database will be automatically failed over to other node.
What’s the purpose of Management Database?
GIMR will be the central repository to store Cluster Health Monitor (aka CHM/OS, ora.crf) and other data in 12c.
Where does Management Database store it’s datafiles?
In 12R1, by default, Management database uses the same shared storage as OCR/Voting File.
Can Management Database be turned on/off when you want ?
In 12.1.0.1, GIMR is optional, if Management Database is not selected to be configured during installation/upgrade OUI, all features (Cluster Health Monitor (CHM/OS) etc) that depend on it will be disabled.
Note: there’s no supported procedure to enable Management Database once the GI stack is configured
This changed in 12.1.0.2, it’s mandatory to have GIMR and must not be turned off
What are the resources associated with Management Database?
The following resources from “crsctl stat res -t” are for Management Database:
ora.mgmtdb
1 ONLINE ONLINE racnode1 Open,STABLE
ora.MGMTLSNR
1 ONLINE ONLINE racnode1 169.254.146.121 172.16.100.61,STABLE
On OS level, the database “-MGMTDB” and listener MGMTLSNR are for Management Database:
[grid@racnode1 ~]$ ps -ef| grep pmon_-MGMTDB
grid 4210 1 0 12:07 ? 00:00:00 mdb_pmon_-MGMTDB
[grid@racnode1 ~]$ ps -ef| grep MGMTLSNR
grid 4015 1 0 12:07 ? 00:00:00 /u01/app/12.1.0/grid/bin/tnslsnr MGMTLSNR -no_crs_notify -inherit
How to start/stop Management Database ?
If Management Database is down for some reason, the following srvctl command can be used to start it:
Usage: srvctl start mgmtdb [-startoption <start_option>] [-node <node_name>]
Usage: srvctl start mgmtlsnr [-node <node_name>]
[grid@racnode1 ~]$ srvctl status MGMTDB
Database is enabled
Instance -MGMTDB is running on node racnode1
[grid@racnode1 ~]$ srvctl status MGMTLSNR
Listener MGMTLSNR is enabled
Listener MGMTLSNR is running on node(s): racnode1
[grid@racnode1 ~]$ srvctl stop MGMTDB
[grid@racnode1 ~]$ srvctl stop MGMTLSNR
[grid@racnode1 ~]$ srvctl status MGMTDB
Database is enabled
Database is not running.
[grid@racnode1 ~]$ srvctl status MGMTLSNR
Listener MGMTLSNR is enabled
Listener MGMTLSNR is not running
[grid@racnode1 ~]$ srvctl start MGMTDB
[grid@racnode1 ~]$ srvctl start MGMTLSNR
PRCC-1014 : MGMTLSNR was already running
PRCR-1004 : Resource ora.MGMTLSNR is already running
PRCR-1079 : Failed to start resource ora.MGMTLSNR
CRS-5702: Resource 'ora.MGMTLSNR' is already running on 'racnode1'
[grid@racnode1 ~]$ srvctl status MGMTDB
Database is enabled
Instance -MGMTDB is running on node racnode1
[grid@racnode1 ~]$ srvctl status MGMTLSNR
Listener MGMTLSNR is enabled
Listener MGMTLSNR is running on node(s): racnode1
How to access to Management Database trace file etc?
Since the database name starts with “-” sign, “./” needs to be specified to avoid error:
[grid@racnode1 grid]$ cd $ORACLE_BASE
[grid@racnode1 grid]$ cd diag
[grid@racnode1 rdbms]$ cd _mgmtdb
[grid@racnode1 _mgmtdb]$ ls -ltr
total 4
drwxr-x--- 16 grid oinstall 4096 Feb 16 21:59 -MGMTDB
-rw-r----- 1 grid oinstall 0 Feb 16 21:59 i_1.mif
[grid@racnode1 _mgmtdb]$ cd -MGMTDB
-bash: cd: -M: invalid option
cd: usage: cd [-L|[-P [-e]]] [dir]
[grid@racnode1 _mgmtdb]$ cd ./-MGMTDB
[grid@racnode1 trace]$ view -MGMTDB_mmon_26447.trc
VIM - Vi IMproved 7.4 (2013 Aug 10, compiled May 4 2014 20:16:04)
Unknown option argument: "-MGMTDB_mmon_26447.trc"
More info with: "vim -h"
[grid@racnode1 trace]$ view ./-MGMTDB_mmon_26447.trc
Is there any need to manually backup or tune Management Database?
As of now, there’s no such need.
How much (shared) disk space should be allocated for the Management Database?
For Oracle Cluster Registry (OCR) with external redundancy and the Grid Infrastructure Management Repository
Minimum: At least 5.2 GB for the OCR volume that contains the Grid Infrastructure Management Repository (4.5 GB + 300 MB voting files + 400 MB OCR), plus 500 MB for each node for clusters greater than four nodes. For example, a six-node cluster allocation should be 6.2 GB.
Reference: http://docs.oracle.com/database/121/CWLIN/storage.htm#CHDDCAHD
Make DBA Life Easy 