State changes that require the system to vault are referred to as vault triggers. There are two types of vault triggers: internal availability triggers and external availability triggers.
Internal availability triggers
Internal availability triggers are initiated when global memory data becomes compromised due to component unavailability. Once these components become unavailable, the system triggers the Need to Vault (NTV) state, and vaulting occurs. There are three internal triggers:
- Vault drive availability: The NVMe vault drives are used for storage of metadata under normal conditions, and for storing any data that is being saved during the vaulting process. PowerMax systems can withstand failure and replacement of NVMe vault drives without impact to processing. However, if the overall available NVMe vault drive space in the system is reduced to the minimum to be able to store the required copies of global memory, the NTV process triggers. This is to ensure that all data is saved before a potential further loss of vault drive space occurs.
- Global memory (GM) availability: When any of the mirrored director pairs are both unhealthy either logically or environmentally, NTV triggers because of GM unavailability.
- Fabric availability: When both the fabric switches are environmentally unhealthy, NTV triggers because of fabric unavailability.
External availability triggers
External availability triggers are initiated under circumstances when global memory data is not compromised, but it is determined that the system preservation is improved by vaulting. There are three external triggers:
- Input power: If power is lost to both power zones, the system vaults.
- Node-Pair trigger: If an entire node-pair fails, the system vaults.
- DME trigger: If the system has lost access to the whole DME or DMEs, including dual-initiator failure, and loss of access causes configured RAID members to become non-accessible, the system vaults.