- 11.1 Workload Distribution Architecture
- 11.2 Resource Pooling Architecture
- 11.3 Dynamic Scalability Architecture
- 11.4 Elastic Resource Capacity Architecture
- 11.5 Service Load Balancing Architecture
- 11.6 Cloud Bursting Architecture
- 11.7 Elastic Disk Provisioning Architecture
- 11.8 Redundant Storage Architecture
- 11.9 Case Study Example
11.8 Redundant Storage Architecture
Cloud storage devices are occasionally subject to failure and disruptions that are caused by network connectivity issues, controller or general hardware failure, or security breaches. A compromised cloud storage device’s reliability can have a ripple effect and cause impact failure across all of the services, applications, and infrastructure components in the cloud that are reliant on its availability.
The redundant storage architecture introduces a secondary duplicate cloud storage device as part of a failover system that synchronizes its data with the data in the primary cloud storage device. A storage service gateway diverts cloud consumer requests to the secondary device whenever the primary device fails (Figure 11.16 and Figure 11.17).
Figure 11.16 The primary cloud storage device is routinely replicated to the secondary cloud storage device (1).
Figure 11.17 The primary storage becomes unavailable and the storage service gateway forwards the cloud consumer requests to the secondary storage device (2). The secondary storage device forwards the requests to the LUNs, allowing cloud consumers to continue to access their data (3).
This cloud architecture primarily relies on a storage replication system that keeps the primary cloud storage device synchronized with its duplicate secondary cloud storage devices (Figure 11.18).
Figure 11.18 Storage replication is used to keep the redundant storage device synchronized with the primary storage device.
Cloud providers may locate secondary cloud storage devices in a different geographical region than the primary cloud storage device, usually for economic reasons. However, this can introduce legal concerns for some types of data. The location of the secondary cloud storage devices can dictate the protocol and method used for synchronization, as some replication transport protocols have distance restrictions.
Some cloud providers use storage devices with dual array and storage controllers to improve device redundancy, and place secondary storage devices in a different physical location for cloud balancing and disaster recovery purposes. In this case, cloud providers may need to lease a network connection via a third-party cloud provider in order to establish the replication between the two devices.