This section describes important considerations and constraints to keep in mind as you plan your Client-mediated High-Availability (HA) group deployment (NOTE: Not to be confused with Clusters and Keyrings). The benefits of HA are described in detail in High-Availability Groups. There are several sample configurations described in this section that take advantage of different HA features. Depending on your organization's security needs, you might choose one of these configurations, or your own variation.
>HSM and Partition Prerequisites
•Performance and Load Balancing
HSM and Partition Prerequisites
The HSM partitions you plan to use in an HA group must meet the following prerequisites before you can use them in an HA group.
Compatible HSM Firmware Versions
All HSMs in an HA group must have the same firmware version installed.
Common Cloning Domain
All key replication in an HA group uses the Luna cloning protocol, which provides mutual authentication, confidentiality, and integrity for each object that is copied from one partition to another. Therefore, all HA group member partitions must be initialized with the same cloning domain. If you are planning to combine already-existing partitions into an HA group, you must first re-initialize them using the same domain string or red PED key.
Common Crypto Officer Credentials
An HA group essentially allows you to log in to all its member partitions simultaneously, using a single credential.
Formerly, it was not possible to create an HA group made up of both password- and multifactor quorum-authenticated partitions. From the advent of Extended Domain Management (see Allow Extended Domain Management ) it is possible to mix authentication types as long as:
>the affected partitions share the same cloning domain
>the multifactor quorum partition is activated (and preferably also auto-activated)
>the challenge secret for the multifactor quorum partition is the same as the password for the password authenticated partition.
Common HSM/Partition Policies (FIPS 140 approved configuration [formerly FIPS mode])
Generally, all HSMs/partitions used in an HA group must have the same policy configuration.
If you are planning to set up an HA group with a mix of FIPS and non-FIPS partitions as members, note the following:
>If you are using Luna HSM Client 10.4.0 or newer, you can set up an HA group with a mix of FIPS and non-FIPS partitions as members. However, some limitations must be considered. For more information, refer to Key Replication.
>If you are using Luna HSM Client 10.3.0 or older, you cannot set up an HA group with a mix of FIPS and non-FIPS partitions as members.
Functionality Modules
If you intend to use Functionality Modules (FMs) with your HA group, all HSMs containing HA group members must have FMs enabled and they must all have the same FM(s) loaded.
Sample Configuration
Your ideal HA group configuration depends on the number of HSMs you have available and the purpose of your application(s).
Performance and Load Balancing
If your application is designed to perform many cryptographic operations as quickly as possible, using keys or other objects that do not change often, you can create a large HA group using partitions on many HSMs. This deployment uses load balancing to provide linear performance gains for each HSM added to the group.
For example: your application uses keys stored on the HSM to perform many encrypt/decrypt or sign/verify operations. You want to minimize transaction latency by providing enough HSMs to handle capacity.
The Luna HSM Client allows HA groups with up to 32 member partitions. The best approach in this example is to add enough group members to handle the usual number of operations, plus enough extra members to handle periods of high demand.
TIP HA Benefits
While client-mediated HA can have benefits with respect to
>up time
>redundancy and failover
>performance increases
...be aware that HA also comes with costs, and that there are exceptions.
Replication of objects across the group takes time; this happens when objects are created or updated via the HA virtual slot.
Finding objects takes longer when multiple partitions are being searched.
Maximum benefit from HA is achieved when objects are created once and used many times, where
>all operations by your application should be directed toward the virtual slot, which takes care of replicating objects, and updates that are performed on objects, to all member partitions/slots and,
>all operations by your application should generally not be directed toward individual slots (in fact, the 'physical' slots that make up an HA group should be hidden by the HAOnly configuration option and not addressed directly) or you risk
•breaking synchronization among members,
•skew of contents with differing versions of objects or keys in different member slots
•error conditions if a call is made against the virtual HA slot and all members do not have the key or object that is expected to undergo parallel operations in the member partitions/slots
If your application creates objects frequently, against the HA virtual slot, the automatic replication across all slots will slow the overall performance. In the case where objects or keys are created to be used once it can be useful to address individual 'physical' slots independently. In such case, you retain standby/rollover advantage of HA, just not a performance enhancement. As soon as keys and objects are no longer useful, they must be deleted, or HA performance is affected by the lookup burden.
