Hardware and Software Requirements

Hardware Requirements

The hardware requirements for your High Availability Add-on (HAA) are different between development and production environments.

Development Environments

Item	Minimum Requirements	Recommended
HAA Nodes	1	3+
RAM	6 GB	8 GB
Storage	10 GB	20 GB

While one node is sufficient for a development environment, three or an odd number of nodes are recommended in order to utilize the clustering features likely needed for your production environment.

Production Environments

Item	Minimum Requirements	Recommended
HAA Nodes	3	3+
Cores per Node	4	8+
RAM	6 GB (15 GB for DR deployments)	30+ GB
Storage	75 GB	150+ GB
Network	1 G	10+ G

Note: Always maintain an odd number of nodes. This is required to obtain a quorum needed in failure and failover scenarios.

Ports

Port	Description
1968	Default port used for internal proxy traffic.
3333-3339 36379-36380	Default port ranges used for internal cluster traffic.
8001	Used for traffic from the application to the Discovery Service, if applicable.
8443	Used for `HTTPS` access to the management UI.
8444 , 9080	Default ports used for internal `nginx < - > cnm_http/cm` traffic.
9081	Default port used for internal CRDB (Conflict-free Replicated Database) traffic.
8070-8071	Used for metrics exported and managed by `nginx`.
9443	Recommended port for REST API traffic.
10000-19999	Port range for database traffic. By default, HAA uses port `10000`.
20000-29999	Port range used for internal database shards traffic.
53,5353	Used for internal `DNS/mDNS` traffic.

Software Requirements

Important: HAA only supports 64-bit operating systems and must be installed on a clean host with no other applications. All HAA nodes must be synchronized with the same NTP server.

Platform	Supported Versions
RHEL/CentOS 7	7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9 Requires OpenSSL 1.0.2 and fw config are required.

General Cluster Requirements

The HAA cluster needs three servers for a healthy operation.

Under normal circumstances, the HAA cluster servers have the following roles:

one principal server – it holds a data shard, and it accepts read and write database operations from the outside world;
one secondary server – it holds a copy of the data shard;
one secondary serve – it holds no data, it exists for quorum purposes only.

The HAA cluster supports a single server failure only.

If one of the servers goes down, no matter which one, the HAA cluster continues working, and a warning is shown in the Web management interface. You can find more information by running the rlcheck command, usually found in /opt/redislabs/bin. You can also append --continue-on-error to the rlcheck command.
If two servers fail, the HAA cluster fails as well, even if the principal server is still online.

Building an HAA cluster with more than three servers is possible but offers no real benefit.

There is no increase in the number of servers that can fail. In the case of a five-node HAA cluster, if the principal node and the secondary node keeping the data shard copy both fail, the entire cluster fails as well, and there is no data shard reallocation to other nodes.