PKCS#11 with HSM Pool mode
If HSM Pool mode is enabled, the nShield PKCS #11 library exposes a single pool of HSMs and a single virtual slot for a fixed token with the label accelerator. This accelerator slot can be used to create module protected keys and to support session objects.
HSM Pool mode supports module protected keys but does not support token-protected keys. If your application only uses module protected keys, you can use HSM Pool mode as an alternative to using load-sharing mode. HSM Pool mode supports returning or adding a hardware security module to the pool without restarting the system.
Whether or not HSM Pool mode is enabled is determined by the state of the CKNFAST_HSM_POOL environment variable.
In FIPS 140 Level 3 Security Worlds, keys cannot be created in HSM Pool mode, however keys created outside HSM Pool mode can be used in HSM Pool mode.
Module failure
If a subset of the modules in the HSM pool fail, the nShield PKCS #11 library handles commands using the remaining modules. When a module fails, any cryptographic functions that were running on that module are restarted on one of the remaining modules. If all of the modules in the HSM pool fail, the nShield PKCS #11 library will return a PKCS #11 error.
Module recovery
If a failed module recovers and remains part of the Security World, it is automatically returned to the HSM Pool and the nShield PKCS #11 library can use it for new commands. If a new module is added to the system that is accessible to the host running the PKCS #11 application, then once the Security World has been loaded onto this HSM, then it is automatically added to the HSM Pool and the nShield PKCS #11 library can use it for new commands.