Of any feature storage administrators could claim to be the most important of a SDS solution, it would arguably be High Availability (HA). Modern business practices demand unprecedented levels of data system uptime and data availability as down time carries a significant cost in lost productivity, sales or customers. QuantaStor's High Availability technology ensures business continuity in the event of a system failure such as a power outage, appliance hardware failure, software crash, or in some cases human error.

QuantaStor High Availability Features

Automatic Failover
The appliances in a High Availability group maintain a continuous "heartbeat" and provide a secondary path to disk storage in the event of a system failure. This transfer of responsibility is seamless to the user and does not require any administrative intervention. The complete transfer occurs in a matter of seconds with little to no interruption in service to the end users.

Data Replication
QuantaStor achieves High Availability by making multiple copies of data that are spread across multiple servers in a cluster to ensure there is no single point of failure. Turn off any node, or in some cases even multiple nodes, and there’s no downtime and near instantaneous fail-over of workloads. Get the speed, reliability and features including snapshots, cloning, thin provisioning and massive scalability all on commodity hardware that can be expanded with RAM and solid state drives (SSDs) to accelerate throughput and IOPS performance.

Simplified Maintenance
Once a High Availability configuration has been established it can also be used to provide business continuity during routine maintenance or software upgrades. The system administrator can manually "fail over" the system to the secondary site and service will resume on the failover site.

Further reading:
QuantaStor v3.15 Released with High Availability Site Clustering for High-Performance Block and File Storage Grids
Deploying a High Availability Storage Cluster with GlusterFS
The Future of High Availability in Software Defined Storage: Ceph and GlusterFS