FAQs
Here are some frequently asked questions about Redis Enterprise Software.
Features and Terminology
Redis Labs has enhanced open source Redis with a technology layer that encapsulates open source Redis, while fully supporting all its commands, data structures and modules. It adds exceptional flexibility, stable high performance and unmatched resilience, as well as multiple deployment choices (public and private clouds, on-premises, hybrid, RAM-Flash combination), topology (active-active, active-passive, active-replica) and support for very large dataset sizes. This enhanced and exponentially more powerful database platform is Redis Enterprise.
Learn more about Redis Enterprise.
Yes we are. Not only are we are the home of Redis, but most of Redis’ core engineers also work for Redis Labs! We contribute extensively to the open source Redis project. As a rule, we adhere to the open source’s specifications and make every effort to update our service with its latest versions.
That said, the following Redis features are not applicable in the context of our service:
- Shared databases aren’t supported in our service given their potential negative impact on performance. We recommend using dedicated databases instead (read this post for more information). Therefore, the following commands are blocked and will produce an error when invoked:
- Data persistence and backups are managed from the service’s web interface, so the following commands are blocked:
- Since replication is managed automatically by the service and since it could present a security risk, the following commands are blocked:
- Redis Labs clustering technology is different than the open source Redis Cluster and supports clustering in a seamless manner that works with all standard Redis clients. As a result, all Cluster related commands are blocked and will produce an error when invoked.
- Redis Labs clustering technology allows multiple active proxies. As a result, the CLIENT ID command cannot guarantee incremental IDs between clients who connect to different nodes under multi proxy policies.
- Commands that aren’t relevant for a hosted Redis service are blocked:
- Additionally, only a subset of Redis’ configuration settings (via CONFIG GET/SET) is applicable to Redis Enterprise Cloud. Attempts to get or set a configuration parameter that isn’t included in the following list will result in an error:
- hash-max-ziplist-entries
- hash-max-ziplist-value
- list-max-ziplist-entries
- list-max-ziplist-value
- notify-keyspace-events
- set-max-intset-entries
- slowlog-log-slower-than (value must be larger than 1000)
- slowlog-max-len (value must be between 128 and 1024)
- zset-max-ziplist-entries
- zset-max-ziplist-value
- Lastly, unlike Redis’ 512MB limit, the maximum size of key names in our service is 64KB (key values, however, can have sizes up to 512MB).
Redis Enterprise Software offers a comprehensive suite of high-availability provisions, including in-memory replication, persistent storage, and backups.
A shard is any type of provisioned Redis instance, such as a master copy, slave copy, database shard that is part of a clustered database, etc.
Redis Enterprise works with all existing standard clients; it does not require you to use any special clients.
You can use, experience and administer the full capabilities of Redis Enterprise Software (RS), but you may not deploy it in a production environment. In addition, the trial version allows a maximum of four shards and is limited to thirty (30) days of use after initial installation on the first server in the cluster. After the thirty day trial, the cluster will shift to read-only status. The free version does not provide the same support options as the paid version. Finally, no SLA is provided with the trial version. To continue operation of the cluster with full capabilities, you must purchase a subscription cluster key from Redis Labs.
Contact us at sales@redislabs.com to learn about RS pricing.
Redis Enterprise Software (RS) works with any standard Redis client. Use your existing Redis client and code, as they work directly against a RS cluster. You point your existing standard Redis client and code connection string at the RS cluster, then scale on the RS cluster as you need.
Technical Capabilities
The number of databases is unlimited. The limiting factor is the available memory in the cluster, and the number of shards in the subscription.
Note that the impact of the specific database configuration on the number of shards it consumes. For example:
- Enabling database replication, without enabling database clustering, creates two shards: a master shard and a slave shard.
- Enabling database clustering creates as many database shards as you configure.
- Enabling both database replication and database clustering creates double the number of database shards you configure.
As explained in the open source Redis FAQ, under "What happens if Redis runs out of memory?":
...[you] can use the "maxmemory" option in the config file to put a limit to the memory Redis can use. If this limit is reached Redis will start to reply with an error to write commands (but will continue to accept read-only commands), or you can configure it to evict keys when the max memory limit is reached in the case you are using Redis for caching.
You can set the maxmemory value of each Redis Enterprise Software database in the management UI using the Memory limit property, as well as configure an eviction policy by setting it to any of the standard Redis behaviors, without interrupting database operations.
RS on Kubernetes
An Operator is a Kubernetes custom controller which extends the native K8s API. Please refer to the article Redis Enterprise K8s Operator-based deployments – Overview.
The Redis Enterprise Operator may only deploy a single Redis Enterprise Cluster per namespace. Each Redis Enterprise Cluster can run multiple databases while maintaining high capacity and performance.
Yes, one Operator per namespace, each managing a single Redis Enterprise Cluster.
Each Redis Enterprise Cluster can run multiple databases while maintaining high capacity and performance.
Run the following:
kubectl get rec
kubectl describe rec my-cluster-nameWhile Helm Charts help automate multi-resource deployments, they do not provide the lifecycle management and lack many of the benefits provided by the Operator:
- Operators are a K8s standards while Helm is a proprietary tool
- Using Operators means the better packaging for different k8s deployments and distributions as Helm is not supported in a straightforward way everywhere
- Operators allow full control over the Redis Enterprise Cluster lifecycle
- We’ve experienced difficulties managing state and lifecycle of the application through Helm as it essentially only allows to determine the resources being deployed, which is a problem when upgrading and evolve the Redis Enterprise Cluster settings
- Operators support advanced flows which would otherwise require using an additional 3rd party
Create a port forwarding rule to expose the cluster UI port. For example, when the default port 8443 is used, run:
$ kubectl port-forward –namespace <namespace> service/<name>-cluster-ui 8443:8443Connect to the UI by pointing your browser to https://localhost:8443
For nodes hosting the Redis Enterprise Cluster statefulSet pods, please follow the guidelines provided for Redis Enterprise in the hardware requirements.
For additional information please also refer to Kubernetes Operator Deployment – Persistent Volumes.
The Redis Enterprise Cluster stores the username/password of the UI in a K8s secret.
To retrieve, first, find the secret by retrieving secrets and locating one of type Opaque with a name identical or containing your Redis Enterprise Cluster name.
For example, run:
$ kubectl get secretsA possible response may look like this:
| NAME | TYPE | DATA | AGE |
|---|---|---|---|
| redis-enterprise-cluster | Opaque | 2 | 5d |
To retrieve the secret run:
$ kubectl get secret redis-enterprise-cluster -o yamlA possible response may look like this:
apiVersion: v1
data:
password: Q2h5N1BBY28=
username: cmVkaXNsYWJzLnNi
kind: Secret
metadata:
creationTimestamp: 2018-09-03T14:06:39Z
labels:
app: redis-enterprise
redis.io/cluster: test
name: redis-enterprise-cluster
namespace: redis
ownerReferences:
– apiVersion: app.redislabs.com/v1alpha1
blockOwnerDeletion: true
controller: true
kind: RedisEnterpriseCluster
name: test
uid: 8b247469-c715-11e8-a5d5-0a778671fc2e
resourceVersion: “911969”
selfLink: /api/v1/namespaces/redis/secrets/redis-enterprise-cluster
uid: 8c4ff52e-c715-11e8-80f5-02cc4fca9682
type: OpaqueNext, decode, for example, the password field. Run:
$ echo "Q2h5N1BBY28=" | base64 –-decodeTo retrieve your password, navigate to the OpenShift management console, select your project name, go to Resources->Secrets->your_cluster_name
Retrieve your password by selecting “Reveal Secret.”
The scc.yaml file is defined like this:
kind: SecurityContextConstraints
apiVersion: v1
metadata:
name: redis-enterprise-scc
allowPrivilegedContainer: false
allowedCapabilities:
- SYS_RESOURCE
runAsUser:
type: RunAsAny
seLinuxContext:
type: RunAsAnyThe SYS_RESOURCE capability is required by the Redis Labs Enterprise Cluster (RLEC) container so that RLEC can set correct OOM scores to its processes inside the container. Also, some of the RLEC services must be able to increase default resource limits, especially the number of open file descriptors.
While the RLEC container runs as user 1001, there are no limits currently set on users and user groups in the default scc.yaml file.
The RLEC SCC definitions are only applied to the project namespace when you apply them to the namespace specific Service Account as described in the OpenShift Getting Started Guide.