What Is Reserved Memory? How Do I Configure Reserved Memory?
Reserved Memory
Reserved memory is part of the memory that is not used for storing data, but for data persistence, master/standby synchronization, and backup.
Parameter reserved-memory-percent is used for configuring reserved memory.
In the monitoring data, the memory usage does not include the usage of reserved memory.
Only the following instances must have reserved memory:
- Single-node DCS Redis 3.0 instances
- Master/standby DCS Redis 3.0 instances
- Single-node DCS Memcached instances
- Master/standby DCS Memcached instances
If reserved memory is insufficient because data occupies too much memory, the following problems may occur:
- Operations on the DCS instance become slow. (The system enables swap, deteriorating the performance.)
- Data cannot be backed up.
- Data cannot be synchronized between the master and standby nodes in time.
- Instance specifications cannot be changed.
- The process may restart.
Procedure for Configuring Reserved Memory
Change the value of reserved-memory-percent by referring to Modifying Configuration Parameters of an Instance.
- Set the parameter to at least 30. For instances created in or after 2021, the default value is 30.
- The percentage takes the maximum available memory, rather than the total memory, as the whole. The available memory is listed in the Available Memory column in DCS Instance Specifications.
Redis Usage FAQs
- Can I Change the CPU Architecture?
- 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 Do I Fail to Delete an 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?
- What Is Reserved Memory? How Do I Configure Reserved Memory?
- Why Is Available Memory Smaller Than Instance Cache Size?
- Why Is Redisson Distributed Lock Not Supported by DCS Proxy Cluster Redis 3.0 Instances?
- Does DCS for Redis Provide Backend Management Software?
- Can I Recover Deleted Data of a DCS Instance?
- Why Is Available Memory of Unused DCS Instances Less Than Total Memory and Why Is Memory Usage of Unused DCS Instances Greater Than Zero?
- How Do I Estimate 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?
- What Are the Constraints on Implementing Multi-DB on a Proxy Cluster Instance?
- How Do I Buy a Multi-DB Proxy Cluster Instance?
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