Manage clusters

This document explains how to connect to and view a MemStore cluster and manage its monitoring, security group, parameter group, and other operational settings.

Manage memory usage

To operate a MemStore cluster reliably, regularly monitor memory usage. When memory reaches the configured maxmemory, eviction is performed according to maxmemory-policy (default: allkeys-lru).

• Valkey maxmemory: About 66%, or two-thirds, of the instance type memory
• Redis OSS maxmemory: About 66% of available system memory

Connect to a MemStore cluster

After creating and configuring a MemStore cluster, you can connect to it with an engine client.

Prerequisites

Prepare the following environment:

• A VM (Virtual Machine) instance that uses the same network as the MemStore cluster
• A security group that permits access to the cluster endpoint

Allow the port configured when the cluster was created: the custom port in the 2000–50000 range or the default TCP 6379 port.

Connect to a cluster

1. See Create and connect to a Virtual Machine instance, connect to the instance, and prepare a Redis or Valkey client.

2. Go to the KakaoCloud Console > Data Store > MemStore.

3. In the Cluster menu, select the cluster.

4. On the Details tab, copy the Endpoint and Port.

5. Run the connection command from the VM instance.

   Connect to a MemStore cluster

   redis-cli -h {ENDPOINT} -p {PORT}

   Item	Description
   {ENDPOINT}	Endpoint on the Details tab
   {PORT}	Connection port - Default: 6379 - Or the custom port specified during cluster creation

Transport encryption and user authentication

For a cluster that uses TLS or user authentication, add the client options required by the cluster settings. You can download the CA file for TLS from the Details tab.

View the cluster list

1. Go to the KakaoCloud Console > Data Store > MemStore.
2. View the cluster list in the Cluster menu.

Item	Description
Name	Name entered during creation; click it to view details
Status	Current cluster status; see Cluster
Engine version	Engine version running on the nodes
Node type	Node type selected during creation; hover to view vCPU and memory information
Cluster mode	Whether cluster mode is enabled
Automatic failover	Whether automatic failover is enabled for node failures - Redis OSS only
Automatic backup retention	Retention period; changes apply to subsequently created automatic backups
Shard count	Number of shards; a hyphen (-) is displayed when cluster mode is disabled - Redis OSS only
Node count	Number of nodes - Redis OSS only
Created at	Date and time when the cluster was created

View cluster details

1. Go to the KakaoCloud Console > Data Store > MemStore.
2. In the Cluster menu, select a cluster.
3. View the information on each tab.

Tab	Description
Details	Operational status, endpoints, and other key cluster information
Shard/Node or Node list	Shards, nodes, and their status; see Manage shards and nodes
Backup	Backup information and operations; see Manage backups
Network/Security	Security groups attached to the cluster
Access control	User authentication and transport encryption settings
Monitoring	Monitoring information for cluster nodes

Details

Item	Description
Name	Cluster name
ID	Cluster ID
Description	Cluster description
Operation status	Current status; see Cluster
Created by	User who created the cluster
Created at	Cluster creation date and time
Cluster mode	Enabled or disabled
Node type	Cluster node type
Shard	Number of shards; displayed when cluster mode is enabled
Node	Number of nodes and automatic failover status
Engine version	Cluster engine version
License	Engine license version
Parameter group	Applied group and status; see Parameter application status
Endpoint	Read/write endpoint when cluster mode is enabled
Primary endpoint	Read/write endpoint when cluster mode is disabled
Read endpoint	Read-only endpoint when cluster mode is disabled
Port	Custom port or default 6379

Shard/Node

See Manage shards and nodes.

Backup

On the Backup tab, you can view backups and create, restore, copy, export, or delete a manual backup.

Item	Description
Backup count	Total number of cluster backups
Automatic backup start time	Configured start time
Automatic backup retention	Configured retention period; changes apply to new backups
Name	Backup name
Status	Backup status; see Backup
Type	Automatic or manual
Memory at backup time	Memory size when the backup was created
Backup file size	Backup file size
Cache size	Backup cache size
Backup start time	Time when backup creation started
Retention expiration	Expiration and deletion time for an automatic backup
[⋮] menu	Restore, copy, export, or delete

Network/Security

View the VPC, availability zone configuration, port, endpoints, topology, attached security groups, and detailed rules. The security group must allow the custom cluster port or default TCP 6379 port.

Access control

View the database user name when user authentication is enabled. When transport encryption is enabled, view the expiration date and download the CA file.

Monitoring

See Monitor a cluster.

Monitor a cluster

1. Go to the KakaoCloud Console > Data Store > MemStore.
2. In the Cluster menu, select the cluster.
3. View the information on the Monitoring tab.

Item	Description
Monitoring node	Node to monitor; a badge identifies the Primary node
Data period	1 hour (default), 3 hours, 12 hours, 1 day, or 7 days
View mode	One, two, or three columns
Automatic refresh interval	Off (default), 10 seconds, 30 seconds, 1 minute, or 5 minutes
Manual refresh	Refreshes monitoring results
Metrics	Engine (Valkey or Redis OSS), CPU, memory, or network

Monitoring data

Category	Metric	Description
Engine	Calls by command (Count/s)	Calls per second by command
Engine	Connections (Count)	Maximum and active connections
Engine	Cache hit ratio (%)	Cache hit ratio over time
Engine	Expired and evicted keys (Count)	Expired and evicted keys over time
CPU	Total usage (%)	Total CPU utilization
CPU	CPU credits (Count)	Displayed only for nodes that use credits
Memory	Total usage (%)	Total memory utilization
Memory	Usage by type (Bytes)	Memory usage by type
Network	Inbound traffic (Bytes/s)	Bytes received per second
Network	Outbound traffic (Bytes/s)	Bytes transmitted per second
Network	Received packets (pps)	Packets received per second
Network	Transmitted packets (PPS)	Packets transmitted per second

Configure automatic failover

Valkey automatically enables automatic failover when a cluster has two or more nodes. For Redis OSS, you can select the setting during cluster creation and change it during operation without service interruption. The following procedure applies to Redis OSS.

Cluster mode and automatic failover

• Automatic failover is always enabled when cluster mode is enabled and cannot be disabled.
• When cluster mode is disabled, the cluster must be in the Running state and have at least one Replica node to enable automatic failover.

1. Go to the KakaoCloud Console > Data Store > MemStore.
2. In Redis OSS > Cluster, click [⋮] for the cluster and select Configure automatic failover.
3. Select whether to use the feature and click [Save].
4. Confirm the setting on the cluster details page.

View security groups

On the Security tab, view the security groups and rules applied to the cluster. The security group must allow the custom cluster port in the 2000–50000 range or the default TCP 6379 port. Click a security group name to manage policies in VPC > Security Group.

Modify security groups

At least one security group must remain attached to the cluster.

1. Go to the KakaoCloud Console > Data Store > MemStore.
2. In the Cluster menu, click [⋮] for the cluster and select Modify security group.
3. Select the security groups to apply and review their inbound and outbound rules.
4. Click [Modify].

Manage security group rules

Manage inbound and outbound rules in VPC > Security Group.

Change a parameter group

Select a parameter group compatible with the cluster engine version and cluster mode. Changes to parameter values can affect an active service, and an additional request can fail if a change is already in progress. See Create and manage parameter groups.

1. Go to the KakaoCloud Console > Data Store > MemStore.
2. In the Cluster menu, click [⋮] for the cluster and select Change parameter group.
3. Select a parameter group and click [Save].

Change the node type

Changing the node type changes every node in the cluster.

Change the node type

• In a single-node cluster, changing the type restarts the node and causes data loss. Use this feature only for clusters with two or more nodes.
• A switchover can cause a temporary interruption.
• Check workload and memory usage first. High load or insufficient target memory can cause data loss, degraded performance, or a failed request.

1. Go to the KakaoCloud Console > Data Store > MemStore.
2. In the Cluster menu, click [⋮] for the cluster and select Change node type.
3. Select a node type and click [Save].

Delete a cluster

Cannot recover after deletion

Deleted cluster resources are permanently released and cannot be recovered.

1. Go to the KakaoCloud Console > Data Store > MemStore.
2. In the Cluster menu, click [⋮] for the cluster and select Delete cluster.
3. Enter Permanent deletion.
4. To retain automatic backups, select Retain automatic backups..
5. Click [Delete].

MemStore user accounts

When user authentication is enabled, authenticate with the ID and password configured during cluster creation. Otherwise, use the passwordless default account.

Supported versions

User authentication is not supported in Redis OSS 5 or earlier.

Command restrictions

For stable service operation, the following Valkey and Redis OSS commands are restricted and return a NOPERM error.

Restricted commands

If a node contains many keys, using KEYS, FLUSHALL, or FLUSHDB can stop the node.

Cluster mode enabled

Command	Description
ACL	ACL-related commands
BGREWRITEAOF	Rewrite the AOF file
BGSAVE	Save in the background
CLIENT PAUSE	Pause clients
CLUSTER ADDSLOTS	Add slots
CLUSTER BUMPEPOCH	Increment the cluster epoch
CLUSTER DELSLOTS	Remove slots
CLUSTER FAILOVER	Perform cluster failover
CLUSTER FLUSHSLOTS	Clear slots
CLUSTER FORGET	Disconnect nodes
CLUSTER MEET	Connect cluster nodes
CLUSTER REPLICATE	Replicate a cluster node
CLUSTER RESET	Reset the cluster
CLUSTER SAVECONFIG	Save cluster configuration
CLUSTER SET-CONFIG-EPOCH	Set the cluster configuration epoch
CLUSTER SETSLOT	Change slot settings
CONFIG	Configure Redis OSS
DEBUG	Debugging commands
FAILOVER	Failover command
MIGRATE	Migrate data
MODULE	Module-related commands
PSYNC	Check replication status
REPLCONF	Change replication settings
REPLICAOF	Configure a Replica
RESTORE-ASKING	Request data restoration
SAVE	Save data
SHUTDOWN	Shut down Redis
SLAVEOF	Configure a Replica
SORT	Sort data
SYNC	Synchronize data

Cluster mode disabled

Command	Description
ACL	ACL-related commands
BGREWRITEAOF	Rewrite the AOF file
BGSAVE	Save in the background
CLIENT PAUSE	Pause clients
CLUSTER	Cluster-related commands
CONFIG	Configure Redis OSS
DEBUG	Debugging commands
FAILOVER	Failover command
MIGRATE	Migrate data
MODULE	Module-related commands
PSYNC	Check replication status
REPLCONF	Change replication settings
REPLICAOF	Configure a Replica
RESTORE-ASKING	Request data restoration
SAVE	Save data
SHUTDOWN	Shut down Redis
SLAVEOF	Configure a Replica
SORT	Sort data
SYNC	Synchronize data