- What's New
- Function Overview
- Service Overview
- Product Bulletin
- Getting Started
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User Guide
- Process of Using DCS
- Creating a User and Granting DCS Permissions
- Buying a DCS Redis Instance
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Accessing a DCS Redis Instance
- Configuring Redis Network Connections
- Controlling DCS Redis Access
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Connecting to Redis on a Client
- Connecting to Redis on redis-cli
- Connecting to Redis on Jedis (Java)
- Connecting to Redis on Lettuce (Java)
- Connecting to Redis on Redisson (Java)
- Connecting to Redis on redis-py (Python)
- Connecting to Redis on go-redis (Go)
- Connecting to Redis on hiredis (C++)
- Connecting to Redis on StackExchange.Redis (C#)
- Connecting to Redis on phpredis (PHP)
- Connecting to Redis on predis (PHP)
- Connecting to Redis on ioredis (Node.js)
- Connecting to Redis on the Console
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Managing Instances
- Viewing and Modifying Basic Settings of a DCS Instance
- Viewing DCS Background Tasks
- Viewing Client Connection Information of a DCS Instance
- Modifying Configuration Parameters of a DCS Instance
- Configuring DCS Instance Parameter Templates
- Configuring DCS Instance Tags
- Renaming Critical Commands for DCS Instances
- Exporting a DCS Instance List
- Performing a Master/Standby Switchover for a DCS Instance
- Managing DCS Instance Shards and Replicas
- Backing Up or Restoring Instance Data
- Changing an Instance
- Managing Lifecycle of an Instance
- Diagnosing and Analyzing an Instance
- Migrating Instance Data
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Testing Instance Performance
- Testing Redis Performance Using memtier_benchmark
- Testing Redis Performance Using redis-benchmark
- Comparing redis-benchmark and memtier_benchmark
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Reference for a Redis Performance Test
- Test Data of Master/Standby DCS Redis 4.0 or 5.0 Instances
- Test Data of Proxy Cluster DCS Redis 4.0 or 5.0 Instances
- Test Data of Redis Cluster DCS Redis 4.0 or 5.0 Instances
- Test Data of Master/Standby DCS Redis 6.0 Instances
- Test Data of Redis Cluster DCS Redis 6.0 Instances
- Test Data of Redis Backup, Restoration, and Migration
- Applying for More DCS Quotas
- Viewing Monitoring Metrics and Configuring Alarms
- Viewing DCS Audit Logs
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Data Migration Guide
- Overview
- Migration Process
- Migration Solution Notes
- Migrating Data from Self-Hosted Redis to DCS
- Migrating Data Between DCS Instances
- Migration from Another Cloud
- Migrating Data from DCS to Self-Hosted Redis
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FAQs
- What Should I Consider When Transferring or Operating Data Between Different OSs?
- Can I Migrate Data from a Multi-DB Source Redis Instance to a Cluster DCS Redis Instance?
- What Are the Constraints and Precautions for Migrating Redis Data to a Cluster Instance?
- What Should I Consider for Online Migration?
- Can I Perform Online Migration Without Any Service Interruption?
- What If "Disconnecting timedout slave" and "overcoming of output buffer limits" Are Reported on the Source Instance During Online Migration?
- Why Is Memory of a DCS Redis Instance Unchanged After Data Migration Using Rump, Even If No Error Message Is Returned?
- Why Are Processes Frequently Killed During Data Migration?
- Is All Data in a DCS Redis Instance Migrated During Online Migration?
- Can I Migrate Data to Multiple Target Instances in One Migration Task?
- Why Does Migration Task Creation Fail?
- How Do I Enable the SYNC and PSYNC Commands?
- Why Does Redis Cluster Migration Fail If It Uses Built-in Keys and Cross-Slot Lua Scripts?
- Handling Migration Errors
- Troubleshooting Data Migration Failures
- Can I Migrate Data from a Lower Redis Version to a Higher One?
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Best Practices
- Serializing Access to Frequently Accessed Resources
- Ranking with Redis
- Implementing Bullet-Screen and Social Comments with DCS
- Merging Game Servers with DCS
- Flashing E-commerce Sales with DCS
- Reconstructing Application System Databases with DCS
- Suggestions on Using Redis
- Redis Client Retry
- Using Nginx for Public Access to Single-node, Master/Standby, or Proxy Cluster DCS Redis Instances
- Using SSH Tunneling for Public Access to a DCS Instance
- Using ELB for Public Access to DCS
- Detecting and Handling Big Keys and Hot Keys
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API Reference
- Before You Start
- API Overview
- Calling APIs
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API V2
- Lifecycle Management
- Parameter Management
- Backup and Restoration
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Cache Analysis
- Creating a Big Key Analysis Task
- Listing Big Key Analysis Tasks
- Querying Big Key Analysis Details
- Deleting a Big Key Analysis Task
- Configuring Automatic Big Key Analysis
- Querying the Configurations of Automatic Big Key Analysis
- Creating a Hot Key Analysis Task
- Listing Hot Key Analysis Tasks
- Querying Hot Key Analysis Details
- Deleting a Hot Key Analysis Task
- Configuring Automatic Hot Key Analysis
- Querying the Configurations of Automatic Hot Key Analysis
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Data Migration
- Creating a Data Migration Task
- Listing Migration Tasks
- Deleting Data Migration Tasks
- Querying Details of a Data Migration Task
- Stopping a Data Migration Task
- Querying the Progress of an Online Migration Task
- Creating an Online Data Migration Task
- Configuring an Online Data Migration Task
- Stopping Data Migration Tasks
- Stopping Synchronization of a Data Migration Task
- Querying Instance tenant-sync
- Modifying Instance tenant-sync
- Shards and Replicas
- Instance Diagnosis
- Log Management
- Tag Management
- Network Security
- Background Task Management
- Other APIs
- Instance Management
- Permissions Policies and Supported Actions
- Appendix
- SDK Reference
-
FAQs
- Instance Types/Versions
-
Feature
- What Are the CPU Specifications of DCS Instances?
- What Are Shard and Replica Quantities?
- Do DCS Redis Instances Limit the Size of a Key or Value?
- Can I Obtain the Addresses of the Nodes in a Cluster DCS Redis Instance?
- Does DCS for Redis Support Redis Clusters?
- What Are Redis Data Eviction Policies?
- Does DCS for Redis Support Read/Write Splitting?
- Does DCS for Redis Support Multi-DB?
- Does DCS Support External Extensions, Plug-ins, or Modules?
- Do DCS Redis Instances Support Data Persistence? What Is the Impact of Persistence?
- Do DCS Redis Instances Limite Data Quantity?
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Security
- How Do I Configure a Security Group?
- Why Can't Security Groups Be Configured for DCS Redis 4.0/5.0/6.0 Basic Edition Instances?
- How Can I Secure My DCS Redis Instances?
- Does DCS Support Cross-AZ Deployment?
- Is a Password Required for Accessing an Instance? How Do I Set a Password?
- Sentinel Principle
- Does DCS Support Sentinels?
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Client and Network Connection
- Troubleshooting Redis Connection Failures
- Does DCS Support Cross-VPC Access?
- Why Is "(error) NOAUTH Authentication required" Displayed When I Access a DCS Redis Instance?
- What Should I Do If Access to DCS Fails After Server Disconnects?
- Why Do Requests Sometimes Time Out in Clients?
- What Should I Do If an Error Is Returned When I Use the Jedis Connection Pool?
- What If "ERR Unsupported CONFIG subcommand" is Displayed in SpringCloud?
- What Can I Do If I Fail to Access a DCS Instance Using Its Domain Name Address?
- What Should Be Noted When Using Redis for Pub/Sub?
- What Can I Do If Error "Cannot assign requested address" Is Returned When I Access Redis Using connect?
- Connection Pool Selection and Recommended Jedis Parameter Settings
- What Can I Do If a Lettuce 6.x Client Is Incompatible with My DCS Instance?
- Should I Use a Domain Name or an IP Address to Connect to a DCS Redis Instance?
- Is the Read-only Address of a Master/Standby Instance Connected to the Master or Standby Node?
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Redis Usage
- Can I Change the AZ for an Instance?
- Can I Change the VPC and Subnet for a DCS Redis Instance?
- Can I Customize or Change the Port for Accessing a DCS Instance?
- Can I Modify the Connection Addresses for Accessing a DCS Instance?
- Why Does It Take a Long Time to Start a Cluster DCS Instance?
- What Should I Do If an Error Occurs in redis_exporter?
- Does DCS for Redis Provide Backend Management Software?
- Can I Recover Deleted Data of a DCS Instance?
- How Do I Check Redis Memory Usage?
- Why Is the Capacity or Performance of a Shard of a Redis Cluster Instance Overloaded When That of the Instance Is Still Below the Bottleneck?
- Why Does an OOM Error Occur During a Redis Connection?
- What Clients Can I Use for Redis Cluster in Different Programming Languages?
- Why Do I Need to Configure Timeout for Redis Cluster?
- Why Am I Seeing a Timeout Error When Reading Data from Redis?
- Explaining and Using Hash Tags
- Why Does a Key Disappear in Redis?
- Will Cached Data Be Retained After an Instance Is Restarted?
- How Do I Know Whether an Instance Is Single-DB or Multi-DB?
- Notes and Procedure for Enabling Multi-DB for Proxy Cluster Instances
- How Do I Create a Multi-DB Proxy Cluster Instance?
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Instance Scaling and Upgrade
- Can I Upgrade Version for a DCS Redis Instance, for Example, from Redis 4.0 to Redis 5.0?
- Are Services Interrupted If Maintenance is Performed During the Maintenance Time Window?
- Are DCS Instances Stopped or Restarted During Specification Modification?
- What DCS Instance Type Changes Are Supported?
- Are Services Interrupted During Specification Modification?
- Why Do I Fail to Modify the Specifications for a DCS Instance?
- How Do I Reduce the Capacity of a DCS Instance?
- How Do I Add Shards to a Cluster DCS Redis Instance Without Changing the Memory?
- How Do I Handle an Error When I Use Lettuce to Connect to a Redis Cluster Instance After Specification Modification?
- Can I Expand a Single Shard of a Cluster Instance (Scale-Up)?
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Data Backup, Export, and Migration
- Can I Migrate Data from a Lower Redis Version to a Higher One?
- What Should I Consider When Transferring or Operating Data Between Different OSs?
- Can I Migrate Data from a Multi-DB Source Redis Instance to a Cluster DCS Redis Instance?
- What Are the Constraints and Precautions for Migrating Redis Data to a Cluster Instance?
- What Should I Consider for Online Migration?
- Can I Perform Online Migration Without Any Service Interruption?
- What If "Disconnecting timedout slave" and "overcoming of output buffer limits" Are Reported on the Source Instance During Online Migration?
- How Do I Export DCS Redis Instance Data?
- Why Is Memory of a DCS Redis Instance Unchanged After Data Migration Using Rump, Even If No Error Message Is Returned?
- Where Are DCS Instance Backup Files Stored? How Many of Them Can Be Stored?
- Is All Data in a DCS Redis Instance Migrated During Online Migration?
- When Will AOF Rewrites Be Triggered?
- What Are the Common Causes of Redis Migration Failures?
- Can I Migrate Data to Multiple Target Instances in One Migration Task?
- How Do I Enable the SYNC and PSYNC Commands?
- Will the Same Keys Be Overwritten During Data Migration or Backup Import?
- Why Does Redis Cluster Migration Fail If It Uses Built-in Keys and Cross-Slot Lua Scripts?
- Handling Migration Errors
- Troubleshooting Data Migration Failures
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Big/Hot Key Analysis
- What Are Big Keys and Hot Keys?
- What Is the Impact of Big Keys or Hot Keys?
- How Do I Avoid Big Keys and Hot Keys?
- How Do I Detect Big Keys and Hot Keys in Advance?
- How Does DCS Delete Expired Keys?
- How Long Are Keys Stored? How Do I Set Key Expiration?
- Why Does Memory Usage Decrease After Big Key Analysis Is Performed on Redis?
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Redis Commands
- Does DCS for Redis Support Command Audits?
- How Do I Clear Redis Data?
- How Do I Find Specified Keys and Traverse All Keys?
- Why Do I Fail to Execute Some Redis Commands?
- Why is "permission denied" Returned When I Run the KEYS Command in Web CLI?
- How Do I Rename High-Risk Commands?
- Does DCS for Redis Support Pipelining?
- Does DCS for Redis Support the INCR and EXPIRE Commands?
- Why Does a Redis Command Fail to Take Effect?
- Is There a Time Limit on Executing Redis Commands? What Will Happen If a Command Times Out?
- Can I Configure Redis Keys to Be Case-Insensitive?
- Common Web CLI Errors
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Monitoring and Alarm
- Why Is CPU Usage of a DCS Redis Instance 100%?
- How Do I View Current Concurrent Connections and Maximum Connections of a DCS Redis Instance?
- What Should I Do If the Monitoring Data of a DCS Redis Instance Is Abnormal?
- Why Is Used Memory Greater Than Available Memory?
- Why Does Bandwidth Usage Exceed 100%?
- Why Is the Rejected Connections Metric Displayed?
- Why Is Flow Control Triggered? How Do I Handle It?
- Master/Standby Switchover
- Instance Creation and Permissions
- Troubleshooting
- Videos
Using ELB for Public Access to DCS
Currently, DCS Redis 4.0, 5.0, and 6.0 instances cannot be bound with elastic IP addresses (EIPs) and cannot be accessed over public networks directly. This section describes how to access a single-node, master/standby, read/write splitting, or Proxy Cluster instance or a node in a Redis Cluster instance through public networks by enabling cross-VPC backend on a load balancer.
- Due to cluster node address translation, you cannot access a Redis Cluster as a whole. You can only access individual nodes in the cluster.
- Do not use public network access in the production environment. Client access exceptions caused by poor public network performance will not be included in the SLA.
The following figure shows the process for accessing DCS through ELB.
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Configurations
- Create a VPC or use an existing one.
- Buy a DCS Redis instance. Record the IP address and port number of the instance.
- Create a dedicated load balancer.
NOTE:
- A shared load balancer does not support cross-VPC backend servers. Therefore, it cannot be bound to a DCS instance.
- For Specification, select Network load balancing (TCP/UDP).
- To access the DCS instance over public networks, enable Cross-VPC Backend when creating a dedicated load balancer.
- Add a TCP listener to the dedicated load balancer.
NOTE:
- When adding a backend server, click the Cross-VPC Backend Servers tab and then click Add Cross-VPC Backend Server.
- In the Add Cross-VPC Backend Server dialog box, enter the IP address and port number of your DCS instance.
- A Redis Cluster DCS instance contains multiple master/replica pairs. When configuring a cross-VPC backend server, you can add the IP address and port number of any master or replica node.
- If you enable Health Check, you do not need to manually configure the port. By default, the service port of the backend server will be used.
- Create a VPC peering connection. For the local VPC, select the VPC where your load balancer is located. For the peer VPC, select the VPC where your DCS instance is located.
NOTE:
Even if your load balancer and DCS instance are in the same VPC, you still need to create a VPC peering connection. For the local VPC, select the VPC where your load balancer and DCS instance are located. For the peer VPC, select another VPC.
- Click the name of the VPC peering connection to go to its details page. Obtain Local VPC CIDR Block and Peer VPC CIDR Block.
- Configure local and peer routes for the VPC peering connection.
- On the Local Routes and Peer Routes tab pages, click the link to go to the route tables page.
- Local route: On the summary page of local routes, click Add Route. In the displayed Add Route dialog box, set Destination to the value of Peer VPC CIDR Block of the VPC peering connection, set Next Hop Type to VPC peering connection, set Next Hop to the VPC peering connection created in 5, and click OK.
- Peer route: On the summary page of peer routes, click Add Route. In the displayed Add Route dialog box, set Destination to the value of Local VPC CIDR Block of the VPC peering connection, set Next Hop Type to VPC peering connection, set Next Hop to the VPC peering connection created in 5, and click OK.
NOTE:
If the load balancer and the DCS instance are in the same VPC, you do not need to add a peer route.
- On the Local Routes and Peer Routes tab pages, click the link to go to the route tables page.
- Perform a health check on the IP address of the DCS instance. If the health check result is Healthy, the added cross-VPC backend IP address can be used.
- On the Elastic Load Balance page, click the name of the created load balancer. The basic information page of the load balancer is displayed.
- On the Backend Server Groups > IP as Backend Servers tab page, view the health check result of the DCS instance IP address.
Connecting to the DCS Instance Through ELB
- Connecting to a node in a Redis Cluster DCS instance through ELB
- View the basic information of the load balancer created in 3.
- Buy an ECS, log in to it, and install the Redis client by referring to redis-cli.
- On the Redis client, connect to the DCS instance using the IP address and port number configured in 4. If you use the EIP and port number of the load balancer, an error will be reported.
- View the basic information of the load balancer created in 3.
- Connecting to a single-node, master/standby, read/write splitting, or Proxy Cluster DCS instance through ELB
- View the IPv4 EIP and port number of the load balancer created in 3.
- Buy an ECS, log in to it, and install the Redis client by referring to redis-cli.
- Use redis-cli to access the load balancer using its EIP and port number (which is 80).
- Write a key through ELB.
- Log in to the DCS console. On the Cache Manager page, choose More > Connect to Redis in the row that contains the DCS instance created in 2. Check whether the key written in 4 exists.
- View the IPv4 EIP and port number of the load balancer created in 3.
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