High Availability and Disaster Recovery deployment options

Supported deployments

Active-Passive

For both high availability (HA) and disaster recovery (DR), Active-Passive deployment is supported. In this kind of setup, a single instance of the application is active. A backup instance, stopped under normal conditions, is ready to be started in case of failure of the main instance - either automatically using a clustering mechanism, or manually following a specific failover procedure.

With Local Disks

In this setup, deployment is typically performed using physical servers and a physical storage system directly attached to the server:

  • Internal RAID card with SAS HDD
  • DAS (Direct Attached Storage)

Disk replication

In order to offer HA capabilities, data need to be replicated from the active node to the passive node. This is usually achieved using rsync-like tools and mechanisms.

Each time the deployment performs a Checkpoint, Flush or Merge data on disk, it will be automatically synchronized to the passive node to maintain a clone of the main configuration & database.

At any time, Axway Decision Insight can then be launched on the failover node; which will recover all states and historical data from the last checkpoint.

The same principle applies to provision a DR instance, usually on a remote location. In order to reduce load on the active node, the replication to the DR site is usually performed from the passive node.

Failover

In order to perform failover between nodes, the deployment relies on external mechanisms, typically a clustered service manager which ensures that a given service is properly running once and only once, and control which instance should be running at a given moment.

The same principle applies to failover to a DR site. It is not unusual to have an automatic failover mechanism for HA, but to rely on manual procedure for DR.

With SAN storage

In this setup, deployment is typically performed using virtualized servers using a SAN (Storage Area Network) as storage subsystem, and sometimes when using physical servers. Connection to the SAN is performed using specific networking mechanisms as:

  • Fiber Channel
  • iSCSI

When deploying over a SAN, it should be noted that Decision Insight has the same Storage (I/O and surface) requirements than a database management system, and should as such be positioned on Tier 0 or 1 of the SAN for performance reasons.

Disk replication

When using a SAN, disk replication is typically handled by the SAN itself within a single datacenter, covering as such the disk replication requirements for HA.

If multi-site SAN replication is in place, it also covers the disk replication requirements for DR. If not available and DR is required, a specific replication mechanism can be setup using the same principles than when using local disks.

Failover

With a virtualized deployment supporting HA

When the virtualization system HA mechanisms are available and deployed (for example, VMware vMotion, VMware HA, VMware FT, etc.), the HA failover typically relies on them for all hardware failures.

Depending on the capabilities of the virtualization system to perform failover over multiple sites, DR can also rely on those mechanisms or require a specific procedure (See With Local Disks > Failover).


With a virtualized deployment without HA

The failover mechanism is similar to With Local Disks > Failover.

Alternatively, a manual or automated procedure can consist in launching the virtual machine on another node instead of launching the application from within a passive virtual machine.


With a physical deployment

The failover mechanism is similar to With Local Disks > Failover.


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