Cost-Effective High-Availability Solutions with HP Instant Capacity on HP-UX

Temporary Instant Capacity and high availability
You can use TiCAP to provide cost-effective high-availability for any of the models covered in the
“HP Serviceguard failover models
” section. To achieve these HA solutions, you must first install iCAP
processors on the cluster nodes. These processors can then be activated temporarily in failover
situations, using additional incremental purchases of TiCAP. This solution provides a less costly
solution because you do not pay full price for the iCAP processors up-front. The solution is
cost-effective because you only pay for extra capacity if a failover situation occurs. Then, you start to
consume your TiCAP balance.
When evaluating an HA solution using TiCAP, you should consider the following:
• TiCAP is typically used only when you do not have any core usage rights to migrate from other
partitions of a server or from other GiCAP group members (if any).
• TiCAP can be used only to activate cores. TiCAP cannot be used for additional cell board and
memory resources.
• TiCAP can be used in any of the Serviceguard failover models. (However, other iCAP solutions may
be more cost-effective, particularly for the rotating standby model where continuous TiCAP
consumption might result when the standby becomes the active node.)
• TiCAP is a flexible and open-ended solution for temporary activation of processor cores.
• TiCAP is used when you can comfortably predict the cost and duration of a failover situation
because it requires additional incremental purchases of capacity.
• TiCAP reserves can be maintained for emergency use while you arrange for long-term solutions.
Example: TiCAP manual failover
A server called Sys1 runs the primary applications for a particular site. You purchase it as a system
with all usage rights (no iCAP components). You equip Sys1 with eight active processor cores on two
cell boards.
At the same time, you purchase server Sys2 with similar characteristics, except that all but two
processor cores are purchased as Instant Capacity processors. (At least one processor core must be
active for each active cell board. The assumption is that Sys2 will normally be running but with very
minimal workloads.)
This means that even though Sys2 is physically a replica of Sys1, the initial cost of Sys2 is
significantly less than the cost of Sys1 because the cost of iCAP processors is a fraction of the cost of
regularly purchased processors.
At the same time, you also purchase three units of TiCAP for potential use on the failover server Sys2,
providing a total TiCAP balance of 90 processor core days. You apply the TiCAP to Sys2. Figure 4
shows the initial configuration before a failure.
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