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 and synchronized with the same NTP server.
| Platform | Supported Versions |
|---|---|
| RHEL/CentOS 7 | 7.0 - 7.6 (Requires at least Minimal Install configuration) |
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
rlcheckcommand, usually found in/opt/redislabs/bin. You can also append--continue-on-errorto therlcheckcommand. - 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.
Updated 6 months ago