This section describes additional configuration options for Redis Enterprise Software installation.
Redis Enterprise Software requires DNS to be properly configured to achieve high availability and fail-over regardless of where it is installed. Here, you learn how to configure AWS Route53 DNS resolution. Prerequisites You need to have a domain name registered. Then, either you need to have Amazon’s Route53 as the primary/master nameserver (NS) for this domain or for a delegated zone under this domain. Finally, you need to have the zone (either the whole domain or a sub-zone) defined in AWS Route53.
CentOS/RHEL7 distributions have, by default, a restrictive firewall mechanism based on firewalld that in turn configures the standard iptables system. The default configuration assigns the network interfaces to the public zone and blocks all ports, except 22 (SSH). Redis Enterprise Software (RS) installation on CentOS/RHEL 7 automatically creates two firewalld system services: A service named redislabs, which includes all ports and protocols needed for communications between cluster nodes. A service named redislabs-clients, which includes the ports and protocols needed for communications external to the cluster.
DNS is critical to the default operation of Redis Enterprise Software deployments. This can be altered, but instead using the Discovery Service, which utilizes pure IP-based connectivity as it is compliant with the Redis Sentinel API. As part of the high availability capabilities in Redis Enterprise Software, each node includes a small DNS server for managing various internal cluster functionalities, such as automatic failover or automatic migration. Therefore, nodes that provision Redis Enterprise Software should run only the DNS server included with the software.
When you want to setup a Redis Enterprise cluster in an environment that doesn’t allow DNS, you can use a load balancer (LB) to direct traffic to the cluster nodes. DNS role for databases Normally, Redis Enterprise uses DNS to provide dynamic database endpoints. A DNS name such as redis-12345.clustername.domain gives clients access to the database resource: If multiple proxies are in use, the DNS name resolves to multiple IP addresses so that clients can load balance.
Swap space is used by the Linux OS to help manage memory (pages) by copying pages from RAM to disk and the OS is configured by default to be fairly aggressive. For Redis Enterprise Software (RS) with the way it utilizes and manages memory, it is best to eliminate the likelihood of the OS swapping. If you would like to understand why, please read more on how RS manages memory for best functionality and performance.
Note: mDNS is only supported for development and testing environments. If you choose to use the mDNS protocol when you set the cluster name, make sure that the configurations and prerequisites for resolving database endpoints are met on the client machines. If you have Active-Passive databases on the cluster, the configurations and prerequisites are also required for the Redis Enterprise Software nodes. To prepare a client or node for mDNS:
There are two default locations for the socket files in Redis Enterprise Software (RS): /tmp - In clean installations of RS version lower than 5.2.2 /var/opt/redislabs/run - In clean installations of RS version 5.2.2 and higher We made this change because some customers have maintenance procedures that delete the /tmp directory. When you upgrade from a RS version lower than 5.2.2 to 5.2.2 and higher, the socket files are not moved to the new location by default.