You must have IP addresses available to create your aliases. If you don't have any IP addresses available, we will show you how to maneuver around the problem in section 16.8 of this chapter. Let's assume you have extra IP addresses to use for your cluster aliases. How many can you create and why would you want to create more aliases? By default, you are limited to creating 8 (7 plus the default cluster alias). If you need more than that, you must alter the max_aliasid attribute in the clua subsystem. This is a dynamic attribute, but be sure to alter it consistently on all cluster members. The last time we checked, the maximum number of cluster aliases was in the range of 102k. That ought to do, don't you think? The following output documents the clua subsystem attributes. Note that max_aliasid is the only one of the clua attributes that you may change without a recommendation from HP engineering.
Aliases in addition to the cluster default alias may be useful for refining the target to a subset of the members of the cluster, or may simply be a different mnemonic that is more meaningful for certain applications. Additional aliases may also be used to off-load routing or service responsibilities from less powerful cluster members.
# sysconfig -q clua max_aliasid clua: max_aliasid = 8
# sysconfig -Q clua max_aliasid clua: max_aliasid - type=INT op=CRQ min_val=2 max_val=102400
The following is an extract from the sys_attrs_clua reference page.
max_aliasid Determines the maximum number of cluster aliases allowed. Although the theoretical maximum is 102,400 aliases, the practical upper limit is memory-restricted. There are no known issues with the use of 100 or so aliases. When increasing the value of this attribute, be sure to increase it consistently on all cluster members before using the additional aliases.