Setting up the netmon.cf file on a TCP/IP network

In a Db2® pureScale® environment running on a TCP/IP protocol over Ethernet (TCP/IP) network, one or more pingable IP addresses must be manually set up in the configuration file netmon.cf. This step is not required, however some restrictions apply. Refer to technote#0733765 for restrictions. When restrictions apply, the netmon.cf file is required by Reliable Scalable Cluster Technology (RSCT) to monitor the network and ensure that the interfaces are pingable or not. For a private network, this file must be set up manually. (On a public network, the Db2 installer updates this file automatically.)

Before you begin

The examples in this topic are based on a Db2 pureScale environment setup with two CFs and two members.

Procedure

To set up the netmon.cf configuration file:

Stop the domain:

Retrieve the cluster manager domain name.

/home/instname/sqllib/bin/db2cluster -cm -list -domain

Stop the domain.

/home/instname/sqllib/bin/db2cluster -cm -stop -domain <domain_name> -force

Set up the configuration file netmon.cf for each host in the cluster:
1. Log in to the host as root.
2. Determine which IP address to enter into each members' netmon.cf configuration file.
  - On AIX® operating systems, to check the communication adapter ports and the associated destination IP subnet, run the netstat command on the member host. For example:
```
netstat -rn
```
```
Routing tables
Destination Gateway Flags Refs Use If Exp Groups

Route Tree for Protocol Family 2 (Internet):
default 9.26.51.1 UG 21 15309923 en0 - -
9.26.51.0 9.26.51.163 UHSb 0 0 en0 - - =>
9.26.51/24 9.26.51.163 U 15 70075017 en0 - -
9.26.51.163 127.0.0.1 UGHS 32 1505251 lo0 - -
9.26.51.255 9.26.51.163 UHSb 0 945 en0 - -
10.1.5.0 10.1.5.13 UHSb 0 0 en1 - - =>
10.1.5/24 10.1.5.13 U 519 3031889427 en1 - -
10.1.5.13 127.0.0.1 UGHS 0 347651 lo0 - -
10.1.5.255 10.1.5.13 UHSb 0 3 en1 - -
127/8 127.0.0.1 U 10 734058 lo0 - -

Route Tree for Protocol Family 24 (Internet v6):
::1%1 ::1%1 UH 2 2463710 lo0 - -
```
    The column "If" lists the adapters on the current host. Choose the adapter that corresponds to the target communication adapter port. In this example, "en1" is the target Ethernet private network adapter. The corresponding IP addresses in the first column show the target IP subnet to be used in the next step. In this case, the IP subnet is "10.1.5.0".
  On most hosts, the same adapters is attached to the same subnet and the /var/ct/cfg/netmon.cf files are identical for all the hosts in the cluster. However, this might not be the case. For example, AIX® configurations on LPARs can have more complex network configurations and each /var/ct/cfg/netmon.cf file can be different.
3. With the IP subnet, use the IP interfaces created on the switch that the current host connects to with the same IP subnet. In the AIX example, assuming the IP interfaces on the switch has IP address 10.1.5.0, this entry is added to the member configuration file/var/ct/cfg/netmon.cf.
  For example, the following entry is added:
```
!REQD en1 10.1.5.0
```
  Where:
  - token1 - !REQD is required entity
  - token2 - en1 is the Ethernet private network interface name on the local host
  - token3 - 10.1.5.0 is the external pingable IP address that is assigned to the interface created on the switch.
  The following is an example of what the full configuration file /var/ct/cfg/netmon.cf looks like for the example member:
```
!REQD en0 9.26.51.1
!REQD en1 10.1.5.0
```
After all the netmon.cf files are updated, the domain must be restarted:
1. Log in to one of the cluster hosts as root.
2. Restart the domain.
```
/home/instname/sqllib/bin/db2cluster -cm -start -domain <domain_name>
```

Verify that all adapters are stable by running the lssrc command:

lssrc -ls cthats

The output is similar to the following:

[root@coralm234 ~]# lssrc -ls cthats
Subsystem         Group            PID     Status
 cthats           cthats           31938   active
Network Name   Indx Defd  Mbrs  St   Adapter ID      Group ID
CG1            [ 0] 3     3     S    192.168.1.234   192.168.1.234
CG1            [ 0] eth0             0x46d837fd      0x46d83801
HB Interval = 0.800 secs. Sensitivity = 4 missed beats
Ping Grace Period Interval = 60.000 secs.
Missed HBs: Total: 0 Current group: 0
Packets sent    : 560419 ICMP 0 Errors: 0 No mbuf: 0
Packets received: 537974 ICMP 0 Dropped: 0
NIM's PID: 31985
CG2            [ 1] 4     4     S    9.26.93.226     9.26.93.227
CG2            [ 1] eth2             0x56d837fc      0x56d83802
HB Interval = 0.800 secs. Sensitivity = 4 missed beats
Ping Grace Period Interval = 60.000 secs.
Missed HBs: Total: 0 Current group: 0
Packets sent    : 515550 ICMP 0 Errors: 0 No mbuf: 0
Packets received: 615159 ICMP 0 Dropped: 0
NIM's PID: 31997
  2 locally connected Clients with PIDs:
 rmcd( 32162) hagsd( 32035)
  Dead Man Switch Enabled:
     reset interval = 1 seconds
     trip  interval = 67 seconds
     Watchdog module in use: softdog
  Client Heartbeating Enabled. Period: 6 secs. Timeout: 13 secs.
  Configuration Instance = 1322793087
  Daemon employs no security
  Segments pinned: Text Data Stack.
  Text segment size: 650 KB. Static data segment size: 1475 KB.
  Dynamic data segment size: 2810. Number of outstanding malloc: 1165
  User time 32 sec. System time 26 sec.
  Number of page faults: 0. Process swapped out 0 times.
  Number of nodes up: 4. Number of nodes down: 0.