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 (default path `/opt/redislabs`)	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 (default path `/opt/redislabs`)	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	Protocol	Description
1968	TCP	Default port used for internal proxy traffic.
3333-3344 36379-36380	TCP	Default port ranges used for internal cluster traffic.
8001	TCP	Used for traffic from the application to the Discovery Service, if applicable.
8443	TCP	Used for `HTTPS` access to the management UI.
8444,9080	TCP	Default ports used for internal `nginx < - > cnm_http/cm` traffic.
9081	TCP	Default port used for internal CRDB (Conflict-free Replicated Database) traffic.
8070-8071	TCP	Used for metrics exported and managed by `nginx`.
9443	TCP	Recommended port for REST API traffic.
10000-19999	TCP	Port range for database traffic. By default, HAA uses port `10000`.
20000-29999	TCP	Port range used for internal database shards traffic.
53,5353	UDP	Used for internal `DNS/mDNS` traffic.
8002,8004,8006	TCP	System health monitoring.
	ICMP	Used to check connectivity between nodes.

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.

The following table lists the OS versions that we tested and confirmed to be compatible with HAA. However, due to the high number of operating system updates and variations, we cannot test compatibility for each combination of HAA version and minor OS version. While we generally expect HAA to work correctly with newer minor OS versions that we did not test, we cannot guarantee compatibility.

If you plan to upgrade to a minor OS version that we do not list in the table, you must perform the upgrade in a testing environment before deploying in a production environment.

Platform	Supported Versions
RHEL/CentOS 8	8.6, 8.8, 8.9
RHEL/CentOS 9	9.3
Ubuntu	20.04 Server version is recommended for production installations. Desktop version is only recommended for development deployments.

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 server – 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.