VSP One SDS Block supports the following functions for fault tolerance. The combination of these functions determines the fault tolerance of the entire storage cluster.
-
User data protection method
-
Redundancy of the storage controller
-
Redundancy of the cluster master node
-
Spread placement group
-
Fault domain
In this document, fault-tolerant system configurations are defined as follows:
If the system can continue to operate when a maximum of one storage node or drive is faulty, the system has a plus-1 redundant configuration. If the system can continue to operate when a maximum of two storage nodes or drives are faulty, the system has a plus-2 redundant configuration.
System operation continuity implies resilience to errors that could otherwise prompt shutdowns, data exchange failures with hosts, or data losses. By setting spread placement groups, the system can tolerate the same number of failures as the number that the redundant configuration allows when failures occur in the AWS hardware. Also, in Multi-AZ configuration, by setting multiple fault domains, the system can tolerate more failures than the redundant configuration allows with respect to failures occurring within the same fault domain.
If the system becomes no longer operable because of, for example, occurrence of more failures than each redundant configuration allows, you might need to reinstall VSP One SDS Block. Back up user data to other storage media in case the system becomes no longer operable. User data cannot be restored by reinstalling VSP One SDS Block.
If the system becomes no longer operable, the maximum time required after failure occurred until acceptance of host I/O stops is two minutes and 20 seconds (in the case of plus-1 redundant configuration) and three minutes and 15 seconds (in the case of plus-2 redundant configuration). Consider these times when designing the application.
The following features of both plus-1 and plus-2 redundant configurations are outlined. Select the configuration that aligns most closely with your priorities for using VSP One SDS Block.
|
Configuration |
Feature |
|---|---|
|
Plus-1 redundant configuration |
|
|
Plus-2 redundant configuration |
|