An Example Policy Set Configuration

Assume that you have a four-node cluster that is used by three different applications, app1, app2, and app3, and that you have created three server pools, pool1, pool2, and pool3. You configure the server pools such that each application is assigned to run in its own server pool, and that app1 wants to have two servers, and app2 and app3 each want one server. The server pool configurations are as follows:

$ crsctl status serverpool pool1 -p
NAME=pool1
IMPORTANCE=0
MIN_SIZE=2
MAX_SIZE=2
SERVER_NAMES=
PARENT_POOLS=
EXCLUSIVE_POOLS=
ACL=owner:mjk:rwx,pgrp:g900:rwx,other::r--
SERVER_CATEGORY=

$ crsctl status serverpool pool2 -p
NAME=pool2
IMPORTANCE=0
MIN_SIZE=1
MAX_SIZE=1
SERVER_NAMES=
PARENT_POOLS=
EXCLUSIVE_POOLS=
ACL=owner:mjk:rwx,pgrp:g900:rwx,other::r--
SERVER_CATEGORY=

$ crsctl status serverpool pool3 -p
NAME=pool3
IMPORTANCE=0
MIN_SIZE=1
MAX_SIZE=1
SERVER_NAMES=
PARENT_POOLS=
EXCLUSIVE_POOLS=
ACL=owner:mjk:rwx,pgrp:g900:rwx,other::r--
SERVER_CATEGORY=

Note:

The crsctl status serverpool command shown in the preceding examples only functions if you created the server pools using CRSCTL.

This configuration, however, does not consider the fact that some applications need server time at different times of the day, week, or month. Email applications, for example, typically use more resources during business hours and use less resources at night and on weekends.

Further assume that app1 requires two servers during business hours, but only requires one server at night and does not require any servers on weekends. At the same time, app2 and app3 each require one server during business hours, while at night, app2 requires two servers and app3 requires one. On the weekend, app2 requires one server and app3 requires three. This scenario suggests three configurations that you must configure for the cluster:

Day Time:
- app1 uses two servers
- app2 and app3 use one server, each
Night Time:
- app1 uses one server
- app2 uses two servers
- app3 uses one server
Weekend:
- app1 is not running (0 servers)
- app2 uses one server
- app3 uses three servers

Policy Set Creation

Given these assumptions, run the crsctl create policyset command to create a policy set with a single policy named Default, which reflects the configuration displayed by the crsctl status serverpool command. You can use the Default policy to create other policies to meet the needs assumed in this example. The crsctl create policyset command creates a text file similar to Example 3-1.

Example 3-1 Policy Set Text File

SERVER_POOL_NAMES=Free pool1 pool2 pool3
POLICY
  NAME=Default
  SERVERPOOL
    NAME=pool1
    IMPORTANCE=0
    MAX_SIZE=2
    MIN_SIZE=2
    SERVER_CATEGORY=
  SERVERPOOL
    NAME=pool2
    IMPORTANCE=0
    MAX_SIZE=1
    MIN_SIZE=1
    SERVER_CATEGORY=
  SERVERPOOL
    NAME=pool3
    IMPORTANCE=0
    MAX_SIZE=1
    MIN_SIZE=1
    SERVER_CATEGORY=

Policy Modification

To modify the preceding policy set to meet the needs assumed in this example, edit the text file to define policies for the three scenarios discussed previously, by changing the name of the policy from Default to DayTime. Then, copy the policy and paste it twice to form two subsequent policies, which you name NightTime and Weekend, as shown in Example 3-2.

Example 3-2 Modified Policy Set Text File

SERVER_POOL_NAMES=Free pool1 pool2 pool3
POLICY
  NAME=DayTime
  SERVERPOOL
    NAME=pool1
    IMPORTANCE=0
    MAX_SIZE=2
    MIN_SIZE=2
    SERVER_CATEGORY=
  SERVERPOOL
    NAME=pool2
    IMPORTANCE=0
    MAX_SIZE=1
    MIN_SIZE=1
    SERVER_CATEGORY=
  SERVERPOOL
    NAME=pool3
    IMPORTANCE=0
    MAX_SIZE=1
    MIN_SIZE=1
    SERVER_CATEGORY=
POLICY
  NAME=NightTime
  SERVERPOOL
    NAME=pool1
    IMPORTANCE=0
    MAX_SIZE=1
    MIN_SIZE=1
    SERVER_CATEGORY=
  SERVERPOOL
    NAME=pool2
    IMPORTANCE=0
    MAX_SIZE=2
    MIN_SIZE=2
    SERVER_CATEGORY=
  SERVERPOOL
    NAME=pool3
    IMPORTANCE=0
    MAX_SIZE=1
    MIN_SIZE=1
    SERVER_CATEGORY=
POLICY
  NAME=Weekend
  SERVERPOOL
    NAME=pool1
    IMPORTANCE=0
    MAX_SIZE=0
    MIN_SIZE=0
    SERVER_CATEGORY=
  SERVERPOOL
    NAME=pool2
    IMPORTANCE=0
    MAX_SIZE=1
    MIN_SIZE=1
    SERVER_CATEGORY=
  SERVERPOOL
    NAME=pool3
    IMPORTANCE=0
    MAX_SIZE=3
    MIN_SIZE=3
    SERVER_CATEGORY=

Notice that, in addition to changing the names of the individual policies, the MAX_SIZE and MIN_SIZE policy attributes for each of the server pools in each of the policies were also modified according to the needs of the applications.

The following command registers the policy set stored in a file with Oracle Clusterware:

$ crsctl modify policyset -file file_name

You can achieve the same results as shown in the previous examples by editing the Default policy set, as a whole, using the crsctl modify policyset command, and by using the crsctl modify serverpool command to change individual server pool attributes for a specific policy.

The following command modifies the Default policy set to manage the three server pools:

$ crsctl modify policyset –attr "SERVER_POOL_NAMES=Free pool1 pool2 pool3"

The following commands add the three policies:

$ crsctl add policy DayTime
$ crsctl add policy NightTime
$ crsctl add policy Weekend

The following commands configure the three server pools according to the requirements of the policies:

$ crsctl modify serverpool pool1 -attr "MIN_SIZE=2,MAX_SIZE=2" -policy DayTime
$ crsctl modify serverpool pool1 -attr "MIN_SIZE=1,MAX_SIZE=1" -policy NightTime
$ crsctl modify serverpool pool1 -attr "MIN_SIZE=0,MAX_SIZE=0" -policy Weekend

$ crsctl modify serverpool pool2 -attr "MIN_SIZE=1,MAX_SIZE=1" -policy DayTime
$ crsctl modify serverpool pool2 -attr "MIN_SIZE=2,MAX_SIZE=2" -policy NightTime
$ crsctl modify serverpool pool2 -attr "MIN_SIZE=1,MAX_SIZE=1" -policy Weekend

$ crsctl modify serverpool pool3 -attr "MIN_SIZE=1,MAX_SIZE=1" -policy DayTime
$ crsctl modify serverpool pool3 -attr "MIN_SIZE=1,MAX_SIZE=1" -policy NightTime
$ crsctl modify serverpool pool3 -attr "MIN_SIZE=3,MAX_SIZE=3" -policy Weekend

There are now three distinct policies to manage the server pools to accommodate the requirements of the three applications.

Policy Activation

The policy set is now configured and controlling the three server pools with three different policies. You can activate policies when necessary, prompting Oracle Clusterware to reconfigure a server pool according to each policy's configuration.

The following command activates the DayTime policy:

$ crsctl modify policyset -attr "LAST_ACTIVATED_POLICY=DayTime"

The current status of the resources is as follows:

$ crsctl status resource -t
--------------------------------------------------------------------------------
Name           Target  State        Server                   State details
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
app1
      1        ONLINE  ONLINE       mjk_has3_2               STABLE
      2        ONLINE  ONLINE       mjk_has3_0               STABLE
app2
      1        ONLINE  ONLINE       mjk_has3_1               STABLE
app3
      1        ONLINE  ONLINE       mjk_has3_3               STABLE

The status of the server pools is as follows:

$ crsctl stat serverpool
NAME=Free
ACTIVE_SERVERS=

NAME=Generic
ACTIVE_SERVERS=

NAME=pool1
ACTIVE_SERVERS=mjk_has3_0 mjk_has3_2

NAME=pool2
ACTIVE_SERVERS=mjk_has3_1

NAME=pool3
ACTIVE_SERVERS=mjk_has3_3

The servers are allocated according to the DayTime policy and the applications run on their respective servers.

The following command activates the Weekend policy (remember, because the server pools have different sizes, as servers move between server pools, some applications will be stopped and others will be started):

$ crsctl modify policyset -attr "LAST_ACTIVATED_POLICY=Weekend"
CRS-2673: Attempting to stop 'app1' on 'mjk_has3_2'
CRS-2673: Attempting to stop 'app1' on 'mjk_has3_0'
CRS-2677: Stop of 'app1' on 'mjk_has3_0' succeeded
CRS-2672: Attempting to start 'app3' on 'mjk_has3_0'
CRS-2677: Stop of 'app1' on 'mjk_has3_2' succeeded
CRS-2672: Attempting to start 'app3' on 'mjk_has3_2'
CRS-2676: Start of 'app3' on 'mjk_has3_2' succeeded
CRS-2676: Start of 'app3' on 'mjk_has3_0' succeeded

The current status of the resources is as follows:

$ crsctl status resource -t
--------------------------------------------------------------------------------
Name           Target  State        Server                   State details      
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
app1
      1        ONLINE  OFFLINE                               STABLE
      2        ONLINE  OFFLINE                               STABLE
app2
      1        ONLINE  ONLINE       mjk_has3_1               STABLE
app3
      1        ONLINE  ONLINE       mjk_has3_0               STABLE
      2        ONLINE  ONLINE       mjk_has3_2               STABLE
      3        ONLINE  ONLINE       mjk_has3_3               STABLE
--------------------------------------------------------------------------------

The status of the server pools is as follows:

$ crsctl status serverpool
NAME=Free
ACTIVE_SERVERS=

NAME=Generic
ACTIVE_SERVERS=

NAME=pool1
ACTIVE_SERVERS=

NAME=pool2
ACTIVE_SERVERS=mjk_has3_1

NAME=pool3
ACTIVE_SERVERS=mjk_has3_0 mjk_has3_2 mjk_has3_3

Using the crsctl modify policyset command, Oracle Clusterware changed server pool configuration, moved servers according to the requirements of the policy, and stopped and started the applications.