An active-active cluster typically comprises at least two nodes, both actively running the same kind of service simultaneously. The primary purpose of an active-active cluster is to achieve load balancing. Load balancing distributes workloads across all nodes to prevent any single node from getting overloaded. Because more nodes are available to serve, there will also be a marked improvement in throughput and response times.
The setup below, which consists of a load balancer and two HTTP servers (ex., two nodes), is an example of this type of HA cluster configuration. Instead of connecting directly to an HTTP server, web clients go through the load balancer, which connects each client to any of the HTTP servers behind it.
Assigning clients to the nodes in the cluster isn't an arbitrary process. Instead, it's based on which load balancing algorithm is set on the load balancer. So, for example, in a "Round Robin" algorithm, the first client to connect is sent to the first server, the second client goes to the second server, the third client goes back to the first server, the fourth client goes back to the second server, and so on. We'll elaborate more on these algorithms in a future post.
Active-Active
For the disaster recovery cluster to operate seamlessly, we recommend configuring the two nodes for redundancy. In other words, their configurations/settings must be virtually identical.
If you're interested, the tutorial How to Setup High Availability File Transfer Servers explains how to achieve redundancy between two MFT servers.
Another thing to remember is that a cluster like this works best when the nodes store files in a shared storage like a NAS. Read Setting Up a NAS Shared Storage for Your File Transfer Servers for more information.
Like the active-active cluster configuration, an active-passive cluster also consists of at least two nodes. However, as "active-passive" implies, not all nodes will be active. In the case of two nodes, for example, if the first node is already active, the second node must be passive or on standby.
The passive (failover) server serves as a backup ready to take over as soon as the active (primary) server gets disconnected or cannot serve, an active-passive failover for when a node fails.
Active-Passive
When clients connect to a two-node cluster in active-passive configuration, they only connect to one server. In other words, all clients will connect to the same server. Like in the active-active configuration, the two servers must have the same settings (ex. redundant).
If changes are made to the settings of the primary server, those changes must be cascaded to the failover server. So when the failover does take over, the clients won't be able to tell the difference.
JSCAPE has two products that enable you to set up an active-active or active-passive (or even a combination of both) failover configuration.
Would you like to try this yourself? JSCAPE MFT Server is platform-agnostic and can be installed on Microsoft Windows, Linux, Mac OS X, and Solaris. It can handle any file transfer protocol and multiple protocols from a single server. Additionally, JSCAPE enables you to handle any file type, including batch files and XML.
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