Creating a DB2® pureScale® instance in a DB2 pureScale environment is only required if you did not choose to create one during installation. DB2 pureScale Environments support only one DB2 pureScale instance.
If you installed DB2 pureScale Feature by using either the DB2 setup wizard or a response file, by default a DB2 pureScale instance is created. However, if you choose to not create the instance during installation, or, if you installed DB2 pureScale Feature by using the db2_install command, you must manually create the DB2 pureScale instance.
Use this topic to create a DB2 pureScale instance after you install the DB2 pureScale Feature.
You can use the db2icrt command to create a DB2 pureScale instance with one cluster caching facility (CF) and one member. The db2icrt command must be issued on either the target CF host or the target member host. The host where the command is issued is referred to as installation-initiating host (IIH).
You can also use the db2isetup command to create an instance. The db2isetup command can also be used to create an instance with multiple hosts, whereas the db2icrt command can create an instance only on two hosts. Regardless of the command used to create the instance, additional hosts can be added by running the db2iupdt command with the -add option.
To ensure optimal performance for a DB2 pureScale instance, the priority level of the log writer engine dispatchable unit (EDU) db2loggw is adjusted to be higher than other EDUs. However, depending on the operating system, in order for this to happen, certain permissions need to be granted to the DB2 database manager. For details on these special permissions see topic Ensuring maximum DB2 workload management dispatcher scheduling accuracy .
Restrictions
When you create a DB2 pureScale instance by using the db2icrt command, you must specify one member and one CF. In a DB2 pureScale environment, the db2icrt command does not support a Lightweight Directory Access Protocol (LDAP) environment.
db2icrt -m <MemberHostName> -mnet <Netname1>
-cf <CFHostName> -cfnet <CFNetname>
-instance_shared_dev <Shared_Device_Path_for_Instance>
-tbdev <Raw_device_for_tiebreaker>
-u <fencedID>
<instanceID>
This syntax diagram is abbreviated for simplicity, see the db2icrt command reference for the full syntax and parameter descriptions. One of the host names specified must be the name of the host that you are running the db2icrt command from.
DB2DIR/instance/db2icrt
-m test1 -mnet test1-ib0
-cf test2 -cfnet test2-ib0,test2-ib1,test2-ib2,test2-ib3
-instance_shared_dev /db2instance
-tbdev /dev/hdisk1
-u db2sdfe1
db2sdin1
The test1-ib0 is the cluster interconnect netname for the test1 member host, the test2-ib0, test2-ib1, test2-ib2, and test2-ib4 are cluster interconnect netnames for the test2 host. This example sets up the cluster caching facility on the test2 host and a DB2 member on the test1 host for the instance db2sdin1 associated with the DB2 installation under /DB2DIR. The cluster interconnect netnames test1-ib0 and test2-ib0 must be on the same IP subnet. The db2sdfe1 value is the fenced user and the db2sdin1 value is the DB2 pureScale instance owner.