Manage cluster

A cluster is an object composed of multiple nodes, and users can perform management tasks such as viewing, monitoring, and deleting clusters. Here's how to manage a cluster:

caution

We recommend regularly monitoring and managing memory usage to ensure that system available memory usage does not exceed 50%.
In KakaoCloud's MemStore service, the maxmemory setting is configured to approximately 65% of the system's available memory, and once the maximum memory is reached, the allkeys-lru policy deletes the least recently used keys among all keys.

View cluster list

You can view the list of clusters created within your project.

1. Go to the KakaoCloud Console > Data Store > MemStore menu.

2. In the Cluster menu, check the list of currently created clusters.

   Item	Description
   Name	The name assigned by the user when creating the cluster - Click the cluster name to view detailed information
   Status	The current status of the cluster - For detailed status values, refer to Cluster lifecycle and status values
   Engine version	The version of the Redis OSS engine running on the node
   Node type	The node type selected by the user when creating the cluster - Hover over the node type to view vCPU and memory information - For node types, refer to Node types
   Cluster mode	Whether cluster mode is enabled
   High availability	Whether automatic failover is enabled in case of node failure
   Auto backup retention period	The retention period set for automatic backups in the cluster - Newly created backups follow the updated retention period after changes - Hover to see the backup start time
   Number of shards	Number of shards in the cluster - If cluster mode is disabled, this is shown as a hyphen (-)
   Number of nodes	Number of nodes created within the cluster
   Uptime	Time elapsed since the cluster was created - Hover to see the creation date

View cluster information

You can check the details of a cluster created within your project.

1. Go to the KakaoCloud Console > Data Store > MemStore menu.

2. In the Cluster menu, select a cluster to view its details.

3. Use the tabs to view information.

   Details tab

   Item	Info	Description
   Top info	Operation status	Current operation status of the cluster
   	Cluster mode	Whether cluster mode is enabled
   	High availability	Whether automatic failover is enabled in case of node failure
   	Endpoint - Primary endpoint	Read/write endpoint
   	Endpoint - Read endpoint	Read-only endpoint - Not available when cluster mode is enabled
   Cluster details	Cluster name	Name given by the user during creation
   	Creator	User who first requested the cluster creation
   	Cluster mode	Whether cluster mode is enabled
   	High availability	Whether automatic failover is enabled
   	Node type	Node type selected during cluster creation (Node types)
   	vCPU per node	Number of virtual CPUs assigned to each node
   	Memory per node	Amount of memory assigned to each node
   	Number of shards	Number of shards in the cluster
   	Number of nodes	Number of nodes in the cluster - Check the Shard/Node list tab for detailed shard and node information
   	Creation date	Time the cluster creation was requested
   	Cluster ID	Object ID of the cluster
   Network	VPC	User-selected VPC during cluster creation
   	Availability zone	Distribution of the cluster across AZs - Multi: Cluster is distributed across two or more AZs - Single: Cluster is in a single AZ
   	Primary endpoint	Read/write endpoint
   	Read endpoint	Read-only endpoint - Not available when cluster mode is enabled
   	Port	Node access port, default is 6379
   Backup	Number of backups	Total number of backups created
   	Auto backup retention period	Retention period of automatic backups - Applies to newly created backups after changes - Hover to view backup start time
   	Auto backup start time	Time when automatic backups begin; starts within 15 minutes of the selected time
   Redis compatibility	Engine version	Redis engine version used in the node
   	License	License information for the Redis OSS engine
   	User authentication	Whether user authentication was enabled during creation
   	ID	Administrator ID if authentication was enabled - Not shown if authentication was not used
   	Parameter group	Applied parameter group and parameter application status; see Parameter application status
   	Transport encryption (TLS)	Whether transport encryption is enabled - When enabled, CA file download is available

   Shard/Node list tab

   Refer to How-to Guides > Manage shards and nodes

   Backup tab

   Create and manage backups from the cluster.
   Backups created from this tab are manual. For more information, refer to Manage backup > Create manual backup

   Item	Description
   Name	Name of the backup
   Status	Current status of the backup - See Backup status values
   Type	Backup type: automatic or manual
   Backup file size	Size of the backup file
   Cache size	Cache size of the backup
   Auto backup retention period	Retention period of automatic backups - Applies to newly created backups after changes - Hover to view backup start time
   Expiration date	Time when the backup is deleted due to retention expiration (for automatic backups only)
   Backup start time	Time when the backup was started
   [More]	Restore, copy, export, delete - See Manage backup for details

   Security tab

   Refer to How-to Guides > Manage cluster > View security group

   Monitoring tab

   Refer to How-to Guides > Manage cluster > Cluster monitoring

Monitor cluster

In the Monitoring tab, you can check the detailed status of nodes in the cluster to manage them flexibly and efficiently, while minimizing the resources required for administration.

1. Go to the KakaoCloud Console > Data Store > MemStore menu.

2. Select the cluster you want to monitor from the Cluster menu.

3. Click the Monitoring tab and review the information.

   Monitoring tab

   Section	Description
   ① Monitoring node	Select the node to monitor
   ② Data period	Select the time range for the monitoring graph - 1 hour (default) / 3 hours / 12 hours / 1 day / 7 days
   ③ Metrics	Select metrics to monitor - MemStore / CPU / Memory / Network - All metrics are selected by default - Multiple selections allowed
   ④ View mode	Set the layout of the monitoring graph - 1-column, 2-column, or 3-column
   ⑤ Auto-refresh interval	Set the auto-refresh interval - None (default) / 10 sec / 30 sec / 1 min / 5 min
   ⑥ Manual refresh	Click to manually refresh the monitoring data

   Available monitoring data

   Category	Metric	Description
   MemStore	Command calls (count/sec)	Number of command calls per second over time
   MemStore	Connections (count)	Number of connections over time - Max connections: Maximum number of clients allowed - Active connections: Number of currently connected clients
   MemStore	Cache hit ratio (%)	Redis cache hit ratio over time
   MemStore	Expired and evicted keys (count)	Number of expired and evicted keys over time
   CPU	Total usage (%)	Total CPU usage over time
   Memory	Total usage (%)	Total memory usage over time
   Memory	Usage by type (Bytes)	Memory usage by type over time
   Network	Interface RX (Bytes/sec)	Network RX usage per second over time
   Network	Interface TX (Bytes/sec)	Network TX usage per second over time
   Network	Interface RX (PPS)	RX packets per second over time
   Network	Interface TX (PPS)	TX packets per second over time

Configure high availability

You can configure the high availability feature provided by MemStore to enhance convenience and ensure stable operation.
When high availability is enabled, node failures are handled automatically. This feature can be configured without any service interruption. Note that the cluster must be in the Running state and have at least one replica node to enable high availability.

info

If cluster mode is enabled, high availability is always on by default and cannot be modified.

1. Go to the KakaoCloud Console > Data Store > MemStore menu.
2. In the Cluster menu, click the [More] icon next to the desired cluster and select Configure high availability.
3. In the High Availability Configuration popup, set the option and click Save.
4. Confirm that high availability is correctly enabled or disabled on the cluster's detail page.

Delete cluster

You can delete clusters that are no longer in use.

caution

Deleted cluster resources are permanently released and cannot be recovered.

1. Go to the KakaoCloud Console > Data Store > MemStore menu.
2. In the Cluster menu, click the [More] icon next to the target cluster and select Delete cluster.
3. In the Delete Cluster popup, enter the name of the cluster to confirm deletion.
4. If you want to preserve automatic backups associated with the cluster, check the option Preserve automatic backups.
5. Click Delete.

MemStore user account

MemStore provides a user authentication option for enhanced access control.
If authentication is enabled, access to resources is granted after authentication using a user-defined ID and password.
If not enabled, resources are accessible through the default passwordless account.

caution

User authentication is not supported for Redis OSS engine versions 5 or below.

Command restrictions

To ensure stable operation and management, the following commands are restricted.
If you attempt to use these commands, a NOPERM error is returned.

caution

If many keys are stored in an instance, using commands like keys, flushall, or flushdb may cause the instance to crash.

When using cluster mode

Command	Description
ACL	ACL-related commands
BGREWRITEAOF	Rewrite the AOF file
BGSAVE	Save in the background
CLIENT PAUSE	Pause client connections
CLUSTER ADDSLOTS	Add cluster slots
CLUSTER BUMPEPOCH	Bump cluster epoch
CLUSTER DELSLOTS	Delete cluster slots
CLUSTER FAILOVER	Trigger cluster failover
CLUSTER FLUSHSLOTS	Reset slots
CLUSTER FORGET	Disconnect nodes
CLUSTER MEET	Connect cluster nodes
CLUSTER REPLICATE	Replicate cluster nodes
CLUSTER RESET	Reset the cluster
CLUSTER SAVECONFIG	Save cluster configuration
CLUSTER SET-CONFIG-EPOCH	Set configuration epoch
CLUSTER SETSLOT	Modify slot settings
CONFIG	Redis OSS configuration settings
DEBUG	Debugging commands
FAILOVER	Manual failover command
MIGRATE	Migrate data
MODULE	Module-related commands
PSYNC	Check replication state
REPLCONF	Modify replication settings
REPLICAOF	Set slave node
RESTORE-ASKING	Restore request
SAVE	Save data manually
SHUTDOWN	Shut down Redis
SLAVEOF	Set master node
SORT	Sort command
SYNC	Synchronization command

When not using cluster mode

Command	Description
ACL	ACL-related commands
BGREWRITEAOF	Rewrite the AOF file
BGSAVE	Save in the background
CLIENT PAUSE	Pause client connections
CLUSTER	Cluster-related commands
CONFIG	Redis OSS configuration settings
DEBUG	Debugging commands
FAILOVER	Manual failover command
MIGRATE	Migrate data
MODULE	Module-related commands
PSYNC	Check replication state
REPLCONF	Modify replication settings
REPLICAOF	Set slave node
RESTORE-ASKING	Restore request
SAVE	Save data manually
SHUTDOWN	Shut down Redis
SLAVEOF	Set master node
SORT	Sort command
SYNC	Synchronization command

View security group

In the Security tab on the cluster detail page, you can view the security groups and associated policies applied to the cluster.
To access the cluster, port 6379 or the custom port you specified must be allowed in the security group.
Click the name of the linked security group in the list to navigate to the detailed VPC > Security Group page for policy management.

Modify security group

You can modify the security groups associated with a cluster.
At least one security group must be connected to the cluster.

1. Go to the KakaoCloud Console > Data Store > MemStore menu.

2. In the Cluster menu, click the [More] icon for the target instance and select Modify security group.

3. In the Modify Security Group popup, select the security groups to apply to the cluster.

   Field	Description
   Selected cluster name	Name of the selected cluster for which you are modifying the security group
   Select security group	Select the security group(s) to apply. Selected groups are displayed as chips below the selection box
   Applied rules	View inbound and outbound rules for each selected security group

4. Click Apply.

info

You can manage inbound and outbound rules from VPC > Security Groups.

Access MemStore cluster

To access a cluster in the MemStore service from an instance, use a Redis client to connect to the cluster created and configured during cluster setup.

Prerequisites

To connect to a cluster, prepare a Virtual Machine instance (node) in the same network as the target cluster, and ensure that it has access to the cluster's endpoint.
In the instance’s security group outbound rules, allow TCP port 6379 (the default port for the cluster) to establish connectivity.

Connect to cluster

You can access the cluster from a connected instance.

1. Refer to Virtual Machine > Create and connect instance to access your instance and install a Redis client if necessary.
   If Redis commands are not recognized, install the Redis client manually.

2. In the KakaoCloud Console, go to the MemStore menu.

3. In the Cluster menu, select the cluster you want to connect to.

4. In the Details tab, find the Endpoint.
   This information is required to run Redis commands, so copy and save it for use.

5. From your instance, run the following Redis command to connect to the cluster:

   Connect to Redis instance

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

   Field	Description
   {ENDPOINT}	Endpoint information retrieved from the Details tab
   {PORT}	Port number for Redis connection; default is 6379 or the user-defined port

info

For more information about instance roles and types, refer to Instance.

Change parameter group

You can change the parameter group associated with a cluster.
You must select a parameter group that matches the cluster's engine version and cluster mode.
If the values of parameters are changed by the new group, it may affect the currently running MemStore service, so it is strongly recommended to review the parameter values before applying.
If a parameter group change is already in progress, a new request may fail.

For more details, refer to Create and manage parameter groups.

1. Go to the KakaoCloud Console > Data Store > MemStore menu.
2. In the Cluster menu, click the [More] icon next to the cluster you want to update, and select Change parameter group.
3. In the Change Parameter Group popup, select the new parameter group and click Confirm.