What is CureMD High Availability Architecture?
CureMD high availability architecture is comprised of multi-layered technologies distributed at multiple sites using redundant equipment to ensure up to 100 % application availability. Inherited application and data layer support ensures continuous availability of the system.
A proven combination of high availability equipment and fault tolerant infrastructure utilizing redundant servers, network and storage devices are employed to perform in a synchronized manger delivering uninterrupted application availability.
- Multi Node Application Servers with Load Balancers
- Multi Node Database Servers – Clustered
- Dual Fiber Channel Controllers
- Multiple WAN links for internet/network redundancy
- Multiple Routing Layers
- Clustered SAN Devices
- Dual SAN Switch
Combined with industry standards, best practices, and world-class software, CureMD system works seamlessly with proven hardware redundancy platforms comprising of hardware fault tolerance, clustering, replication, and data mirroring technologies to help ensure high availability, stability, and scalability.
CureMD system supports clustering technologies to help ensure maximum availability. To prepare for a site outage, data replication technologies are deployed with clustering technologies to provide an integrated disaster recovery solution—so that both the application and the data can be accessed form a secondary site, without distance limitations and with minimal disruption.
Configuration Highlights:
- Fully automated fail-over
- Soft installation, without the need to reconfigure the servers
- Seamless integration with the environment, including security, bandwidth management, and alarm-reporting mechanisms
- Automated hardware, OS, and application state verification
- Automated transfer of network resources during fail-over
- Ability to recognize and record databases consistent state points
- Complete rollback of changes in the event of unsuccessful fail-over
- Ability to delay replay or enable rewind capability on replicas
- Ability to fully integrate with security environment
- Centralized scenario management
- Bandwidth utilization controls
High Availability Architecture
CureMD replicates data from an active server (Node A), to a passive server (Node B). In case of active server failures, passive server can take over processing and assume full identity of node A, without compromising application or service availability. The two servers are located next to each other to provide additional protection against component failures and or software crashes. An exact replica of the HA design at the secondary site offers protection against site failures and plays a vital role in the development and implementation of a mission critical business continuity plan.
Fault Tolerance
CureMD incorporates fault-tolerant systems for continuous operations in the event of failure of one or more components. Roll-forward and roll-back recovery procedures ensure expedited recovery in case of error or failure. Following best practices have been used to ensure fault tolerance:
- No single point of failure
- No single point of repair
- Fault isolation to the failing component
- Fault containment to prevent propagation of the failure
- Availability of reversion modes
SQL Server Failover Clustering
Failover clustering provides high-availability support for an entire instance of SQL Server. CureMD Databases are each installed into a cluster group, known as a resource group. At any time, each resource group is owned by only one node in the cluster. The service has a virtual name that is independent of the node names, and is referred to as the fail-over cluster instance name. CureMD database connect to the fail-over cluster instance by referencing the fail-over cluster instance name. A CureMD system fail-over cluster instance appears on the network as a single computer, but has functionality that provides fail-over from one node to another if the current node becomes unavailable. For example, during a non-disk hardware failure, operating system failure, or planned operating system upgrade, an instance of the system on one node can be configured to fail over to any other node in the disk group.
SAN Clustering
CureMD system support clustered SAN environment that creates high availability at the point where server and SAN connects. We use two Fiber Channel host bus adapters (HBAs) connected to each server. HBA’s in use support hot standby, load sharing and load balancing capabilities.
Application Load Balancing
CureMD implements load balancing through dedicated or virtual load balancers to provide application front end fail-over and load balancing. CureMD implements two switches for each HBA. Each switch has the same set of servers and storage connected to it, thus providing for two or more independent access paths from server to the data. As with the server each data storage unit has multiple paths of access, as well as the ability to support the same type of features as the server HBA for hot spare, load sharing and load balancing. The data is situated according to the various RAID levels, both for speed of data access and availability.
