network configuration in a cluster

[shinya_1]

Please help me.
I want to define 'lan5' as standby network interface of 'lan2' and editted /etc/cmcluster/cmclconf.ascii as follows.


---------------------------------
NETWORK_INTERFACE lan4
STATIONARY_IP 10.144.110.10
NETWORK_INTERFACE lan0
NETWORK_INTERFACE lan2
STATIONARY_IP 10.144.110.70
NETWORK_INTERFACE lan5
NETWORK_INTERFACE lan6
HEARTBEAT_IP 10.144.112.162
---------------------------------

After I halted the cluser, I executed 'cmapplyconf -C /etc/cmcluster/cmclconf.ascii'.
But the result of the command 'cmgetconf' is as follows.

---------------------------------
NETWORK_INTERFACE lan4
STATIONARY_IP 10.144.110.10
NETWORK_INTERFACE lan2
STATIONARY_IP 10.144.110.70
NETWORK_INTERFACE lan6
HEARTBEAT_IP 10.144.112.162
NETWORK_INTERFACE lan0
NETWORK_INTERFACE lan5
---------------------------------

To change the definition of cluser as I am wanting, what should I do?

[RAC_1]

Can you post following?

cmgetconf -v -c "cluster_name" "out_put_file"
and also "out_put" file.

[shinya_1]

Please see the attached file.

[John Bigg · Accepted solution]

The position of the entries in the cluster ascii file is irrelevant. You do not need to specify the standby lans directly after the primary lans in order for them to be considered as a standby. The order is unimportant.

What is important is the connectivity. If lan5 is physically bridged to lan2 then it will automatically be a standby lan for lan2 irrespective of the positioning of the entries in the ascii file.

This can sometimes lead to undesired situations. For example if you have 2 subnets bridged together with a mixture of 10BT and 100BT cards and have 1 10BT standby and 1 100BT standby you cannot specify which card should be used for what. i.e. it is possible for the 10BT card to be picked as the standby card to use should the 100BT primary fail. The only way to avoid this is to ensure you only bridge together the lans you want to be used together.

If you have a number of standby lans bridged together they are treated as a pool of standby cards and you cannot define which card is used when any of the primaries fail.

If you look at the cluster ascii file created by cmquerycl you will see comments which indicate which cards are standby for which others. For example:

# Possible standby Network Interfaces for lan0: lan1.

[John Bigg]

From the file you attached:

# Primary Network Interfaces on Bridged Net 1: lan4.
# Possible standby Network Interfaces on Bridged Net 1: lan0.
# Primary Network Interfaces on Bridged Net 2: lan2.
# Possible standby Network Interfaces on Bridged Net 2: lan5.
# Primary Network Interfaces on Bridged Net 3: lan6.
# Warning: There are no standby network interfaces on bridged net 3.

This indicates that lan5 is a standby for lan2, they are both configured on bridged net 2. Therefore this is configured as you wanted.

[shinya_1]

Jhon and RAC
Thank you for your instruction!

[shinya_1]

lan2 was switched to lan5, when lan2 failed.
Thanks a lot!

[RAC_1]

No points please. something to learn today. I was under the impression that the standby is decided in the oerder defined.

Question for John,

If four lans are on same brideg net, how standby will be deicded. (I understand that this then will be SPOF).
But just egaer to know how it will be decided then?

[John Bigg]

RAC, If there are multiple standby lans the order is indeterminate and any could be chosen. In reality SG holds a list of the standbys and simply pulls them off this list in order when a failure occurs. But you cannot reply on this and cannot reliably determine the order in which they are placed into this list.