In a DBA’s routine, we perform thousands of command every day. Sometimes it also happens we don’t know the post-impact of the command.

Then, Oracle 12c Comes up with very powerful feature WHAT IF EVALUATION.

It shows us the impact of command without actually performing it. So with help of this our life can become easier, first perform an evaluation of command you want to actually apply to your production.

We can use eval and predict with CRSCTL[Cluster Control] and SRVCTL[Server Control].

Let us understand each one with a simple example :

  1. Use of eval in CRSCTL
    [oracle@rac1 ~]$ crsctl eval stop resource ora.cvu -unsupported
    Stage Group 1:
    Stage Number	Required	Action	
         1		    Y		Resource 'ora.cvu' (1/1) will be in state
    [oracle@rac1 ~]$
  2. Use of Predict in SRVCTL

    [oracle@rac1 ~]$ srvctl predict -h
    The SRVCTL predict command evaluates the consequences of resource failure.
    Usage: srvctl predict database -db <database_name> [-verbose]
    Usage: srvctl predict service -db <database_name> -service <service_name> [-verbose]
    Usage: srvctl predict asm [-node <node_name>] [-verbose]
    Usage: srvctl predict diskgroup -diskgroup <diskgroup_name> [-verbose]
    Usage: srvctl predict filesystem -device <volume_device> [-verbose]
    Usage: srvctl predict vip -vip <vip_name> [-verbose]
    Usage: srvctl predict network [-netnum <network_number>] [-verbose]
    Usage: srvctl predict listener -listener <listener_name> [-verbose]
    Usage: srvctl predict scan -scannumber <scan_ordinal_number> [-netnum <network_number>] [-verbose]
    Usage: srvctl predict scan_listener -scannumber <scan_ordinal_number> [-netnum <network_number>] [-verbose]
    Usage: srvctl predict oc4j [-verbose]


    [oracle@rac1 ~]$ srvctl predict asm -verbose
    Resource ora.asm will be stopped
    Resource ora.mgmtdb will be stopped
    Resource ora.DATA.dg will be stopped
    Resource ora.MGMTLSNR will be started on node rac2
    Resource ora.mgmtdb will be stopped
    Resource ora.mgmtdb will be started on node rac2
    [oracle@rac1 ~]$

Stay tuned for More articles on Oracle RAC

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