Podcast
Questions and Answers
What is the recommended action if the CPUUtilization metric exceeds 90%?
What is the recommended action if the CPUUtilization metric exceeds 90%?
- Reduce the ConnectionOverhead parameter value
- Scale your cache cluster down by using a smaller cache node type
- Scale your cache cluster up by using a larger cache node type (correct)
- Investigate the application behavior to address the issue
What does the SwapUsage metric measure?
What does the SwapUsage metric measure?
- The efficiency in the allocation of memory of the Redis engine
- The number of client connections to the cache cluster
- The number of successful read-only key lookups in the main dictionary
- The amount of swap space used in bytes (correct)
What is the purpose of Redis Auth?
What is the purpose of Redis Auth?
- To bill partial Node-hours consumed as full hours
- To authenticate requests to AWS resources
- To log all Amazon ElastiCache actions
- To require a token (password) before allowing clients to run commands (correct)
What is the unit of pricing for ElastiCache?
What is the unit of pricing for ElastiCache?
What is the recommended value for the MemoryFragmentationRatio metric?
What is the recommended value for the MemoryFragmentationRatio metric?
What does the CacheHitRate metric indicate?
What does the CacheHitRate metric indicate?
What type of policies can be used with Amazon ElastiCache to provide necessary access?
What type of policies can be used with Amazon ElastiCache to provide necessary access?
What is the purpose of AWS CloudTrail?
What is the purpose of AWS CloudTrail?
What is the Evictions metric used for?
What is the Evictions metric used for?
What is not charged in ElastiCache?
What is not charged in ElastiCache?
What is a primary feature of ElastiCache Memcached compared to Redis?
What is a primary feature of ElastiCache Memcached compared to Redis?
Which statement about ElastiCache clusters is accurate?
Which statement about ElastiCache clusters is accurate?
Which caching strategy is characterized by automatically loading data when it is requested?
Which caching strategy is characterized by automatically loading data when it is requested?
What is the maximum number of shards allowed in Redis when cluster mode is enabled?
What is the maximum number of shards allowed in Redis when cluster mode is enabled?
What is a key use case for ElastiCache?
What is a key use case for ElastiCache?
Which feature is unique to Redis compared to Memcached?
Which feature is unique to Redis compared to Memcached?
What does TTL stand for in the context of caching?
What does TTL stand for in the context of caching?
Which of the following options indicates a limitation of ElastiCache Memcached?
Which of the following options indicates a limitation of ElastiCache Memcached?
What is the primary purpose of maintenance windows in ElastiCache?
What is the primary purpose of maintenance windows in ElastiCache?
In Redish, how are replicas distributed across availability zones?
In Redish, how are replicas distributed across availability zones?
What is the primary purpose of ElastiCache?
What is the primary purpose of ElastiCache?
Which statement about ElastiCache nodes is correct?
Which statement about ElastiCache nodes is correct?
Which of the following statements is true about the billing of ElastiCache?
Which of the following statements is true about the billing of ElastiCache?
What is a characteristic of the ElastiCache service concerning data storage?
What is a characteristic of the ElastiCache service concerning data storage?
What are subnet groups in the context of ElastiCache?
What are subnet groups in the context of ElastiCache?
Which of the following is NOT a type of instance for ElastiCache?
Which of the following is NOT a type of instance for ElastiCache?
How is access to ElastiCache nodes regulated when deployed in a VPC?
How is access to ElastiCache nodes regulated when deployed in a VPC?
Which workload type is ElastiCache best suited for?
Which workload type is ElastiCache best suited for?
Which option correctly describes the nature of nodes in ElastiCache?
Which option correctly describes the nature of nodes in ElastiCache?
What happens if an existing ElastiCache Cluster is moved outside of a VPC?
What happens if an existing ElastiCache Cluster is moved outside of a VPC?
What is the key use case for ElastiCache?
What is the key use case for ElastiCache?
What is the primary purpose of maintenance windows in ElastiCache?
What is the primary purpose of maintenance windows in ElastiCache?
What is a key difference between Redis and Memcached engines?
What is a key difference between Redis and Memcached engines?
What is a characteristic of the ElastiCache service concerning data storage?
What is a characteristic of the ElastiCache service concerning data storage?
What is the maximum number of nodes per region for Memcached?
What is the maximum number of nodes per region for Memcached?
What is the primary purpose of Redis shards?
What is the primary purpose of Redis shards?
What is a limitation of ElastiCache Memcached?
What is a limitation of ElastiCache Memcached?
What is the primary purpose of Redis replication?
What is the primary purpose of Redis replication?
What is the difference between Lazy Loading and Write-Through caching strategies?
What is the difference between Lazy Loading and Write-Through caching strategies?
How is access to ElastiCache nodes regulated when deployed in a VPC?
How is access to ElastiCache nodes regulated when deployed in a VPC?
What is the primary purpose of ElastiCache?
What is the primary purpose of ElastiCache?
Which type of workloads is ElastiCache best suited for?
Which type of workloads is ElastiCache best suited for?
What is a key characteristic of ElastiCache nodes?
What is a key characteristic of ElastiCache nodes?
How is access to ElastiCache nodes regulated when deployed within a VPC?
How is access to ElastiCache nodes regulated when deployed within a VPC?
What are subnet groups in the context of ElastiCache?
What are subnet groups in the context of ElastiCache?
Which of the following statements is TRUE about ElastiCache billing?
Which of the following statements is TRUE about ElastiCache billing?
What is a primary characteristic of ElastiCache's data storage mechanism?
What is a primary characteristic of ElastiCache's data storage mechanism?
Which of the following options is NOT a valid instance type for ElastiCache?
Which of the following options is NOT a valid instance type for ElastiCache?
What is a common use case for ElastiCache in terms of application data?
What is a common use case for ElastiCache in terms of application data?
Which statement about ElastiCache clusters is accurate?
Which statement about ElastiCache clusters is accurate?
Which metric provides insight into the efficiency of memory allocation in ElastiCache Redis?
Which metric provides insight into the efficiency of memory allocation in ElastiCache Redis?
What is the recommended course of action if the SwapUsage metric for Memcached exceeds 50MB?
What is the recommended course of action if the SwapUsage metric for Memcached exceeds 50MB?
Which metric is specifically designed to analyze the load of the Redis process itself?
Which metric is specifically designed to analyze the load of the Redis process itself?
What is the recommended action if the CacheHitRate metric for Redis falls below ~0.8?
What is the recommended action if the CacheHitRate metric for Redis falls below ~0.8?
What is the purpose of Redis Auth?
What is the purpose of Redis Auth?
Which of the following statements is true about ElastiCache pricing?
Which of the following statements is true about ElastiCache pricing?
What is the primary purpose of AWS CloudTrail in the context of ElastiCache?
What is the primary purpose of AWS CloudTrail in the context of ElastiCache?
Which metric indicates the number of successful read-only key lookups in the main Redis dictionary?
Which metric indicates the number of successful read-only key lookups in the main Redis dictionary?
Which statement accurately describes the behavior of the Evictions metric for Memcached?
Which statement accurately describes the behavior of the Evictions metric for Memcached?
Which of the following options is NOT a characteristic of ElastiCache Memcached?
Which of the following options is NOT a characteristic of ElastiCache Memcached?
What is the primary benefit of using ElastiCache for read-heavy application workloads or compute-intensive workloads?
What is the primary benefit of using ElastiCache for read-heavy application workloads or compute-intensive workloads?
What is a node in ElastiCache?
What is a node in ElastiCache?
What is the purpose of subnet groups in ElastiCache?
What is the purpose of subnet groups in ElastiCache?
How are failed nodes replaced in ElastiCache?
How are failed nodes replaced in ElastiCache?
What is a key benefit of using ElastiCache with applications that require high performance?
What is a key benefit of using ElastiCache with applications that require high performance?
What type of workloads is ElastiCache best suited for?
What type of workloads is ElastiCache best suited for?
What is a key difference between the Memcached and Redis engines in ElastiCache?
What is a key difference between the Memcached and Redis engines in ElastiCache?
What can be stored in ElastiCache?
What can be stored in ElastiCache?
What is the purpose of maintenance windows in ElastiCache?
What is the purpose of maintenance windows in ElastiCache?
What is a characteristic of ElastiCache nodes?
What is a characteristic of ElastiCache nodes?
How is access to ElastiCache nodes controlled when not using a VPC?
How is access to ElastiCache nodes controlled when not using a VPC?
What is a key use case for ElastiCache?
What is a key use case for ElastiCache?
What is the minimum scope of an ElastiCache cluster?
What is the minimum scope of an ElastiCache cluster?
What is a limitation of ElastiCache Memcached?
What is a limitation of ElastiCache Memcached?
What is a key use case for ElastiCache?
What is a key use case for ElastiCache?
What is the purpose of Redis shards in ElastiCache?
What is the purpose of Redis shards in ElastiCache?
What is the billing model for ElastiCache?
What is the billing model for ElastiCache?
What is the primary purpose of Redis replication in ElastiCache?
What is the primary purpose of Redis replication in ElastiCache?
What is the primary purpose of Lazy Loading caching strategy?
What is the primary purpose of Lazy Loading caching strategy?
What is the primary purpose of Write-Through caching strategy?
What is the primary purpose of Write-Through caching strategy?
What metric should be monitored to detect possible issues with the application behavior?
What metric should be monitored to detect possible issues with the application behavior?
What is the purpose of the MemoryFragmentationRatio metric in ElastiCache Redis?
What is the purpose of the MemoryFragmentationRatio metric in ElastiCache Redis?
How does AWS CloudTrail help with security in ElastiCache?
How does AWS CloudTrail help with security in ElastiCache?
What determines the pricing of ElastiCache?
What determines the pricing of ElastiCache?
What is the purpose of the Evictions metric in ElastiCache Memcached?
What is the purpose of the Evictions metric in ElastiCache Memcached?
What is the advantage of using Redis Auth with ElastiCache Redis?
What is the advantage of using Redis Auth with ElastiCache Redis?
What type of metric is CPUUtilization in ElastiCache Memcached?
What type of metric is CPUUtilization in ElastiCache Memcached?
What is the recommended action if the SwapUsage metric exceeds 50 MB?
What is the recommended action if the SwapUsage metric exceeds 50 MB?
What is the purpose of the CacheHitRate metric in ElastiCache Redis?
What is the purpose of the CacheHitRate metric in ElastiCache Redis?
What is the unit of billing for ElastiCache?
What is the unit of billing for ElastiCache?
What is the primary purpose of ElastiCache?
What is the primary purpose of ElastiCache?
What is the key difference between Lazy Loading and Write-Through caching strategies?
What is the key difference between Lazy Loading and Write-Through caching strategies?
What is a limitation of ElastiCache Memcached?
What is a limitation of ElastiCache Memcached?
What is the maximum number of nodes per region for Memcached?
What is the maximum number of nodes per region for Memcached?
What is the primary purpose of Redis shards?
What is the primary purpose of Redis shards?
What is the purpose of maintenance windows in ElastiCache?
What is the purpose of maintenance windows in ElastiCache?
What is a key characteristic of ElastiCache nodes?
What is a key characteristic of ElastiCache nodes?
What is a primary feature of ElastiCache Memcached compared to Redis?
What is a primary feature of ElastiCache Memcached compared to Redis?
What is the primary purpose of Redis replication?
What is the primary purpose of Redis replication?
What is a common use case for ElastiCache in terms of application data?
What is a common use case for ElastiCache in terms of application data?
What does the CPUUtilization metric measure in ElastiCache Memcached?
What does the CPUUtilization metric measure in ElastiCache Memcached?
What can you do to address a high Evictions metric in ElastiCache Memcached?
What can you do to address a high Evictions metric in ElastiCache Memcached?
What is the purpose of logging and auditing in Amazon ElastiCache?
What is the purpose of logging and auditing in Amazon ElastiCache?
What is the unit of pricing for ElastiCache?
What is the unit of pricing for ElastiCache?
What is the purpose of Redis Auth in Amazon ElastiCache?
What is the purpose of Redis Auth in Amazon ElastiCache?
What does the EngineCPUUtilization metric measure in ElastiCache Redis?
What does the EngineCPUUtilization metric measure in ElastiCache Redis?
What is the purpose of the CacheHits metric in ElastiCache Redis?
What is the purpose of the CacheHits metric in ElastiCache Redis?
What is not charged in ElastiCache?
What is not charged in ElastiCache?
What is a characteristic of ElastiCache high availability?
What is a characteristic of ElastiCache high availability?
What does the MemoryFragmentationRatio metric indicate in ElastiCache Redis?
What does the MemoryFragmentationRatio metric indicate in ElastiCache Redis?
What is the smallest building block of ElastiCache?
What is the smallest building block of ElastiCache?
What type of workloads is ElastiCache particularly suited for?
What type of workloads is ElastiCache particularly suited for?
How are ElastiCache nodes deployed within a VPC regulated?
How are ElastiCache nodes deployed within a VPC regulated?
What is the billing model for ElastiCache based on?
What is the billing model for ElastiCache based on?
What happens to failed nodes in ElastiCache?
What happens to failed nodes in ElastiCache?
Which statement is true regarding ElastiCache's data storage characteristics?
Which statement is true regarding ElastiCache's data storage characteristics?
Which of the following accurately describes the accessibility of ElastiCache nodes?
Which of the following accurately describes the accessibility of ElastiCache nodes?
What is a common use for cached information in ElastiCache?
What is a common use for cached information in ElastiCache?
What must be configured when deploying ElastiCache within a VPC?
What must be configured when deploying ElastiCache within a VPC?
What type of ElastiCache instances are available besides on-demand?
What type of ElastiCache instances are available besides on-demand?
What is the primary benefit of using ElastiCache for read-heavy application workloads or compute-intensive workloads?
What is the primary benefit of using ElastiCache for read-heavy application workloads or compute-intensive workloads?
What is a characteristic of ElastiCache nodes?
What is a characteristic of ElastiCache nodes?
What is the purpose of subnet groups in ElastiCache?
What is the purpose of subnet groups in ElastiCache?
What happens when an ElastiCache node fails?
What happens when an ElastiCache node fails?
What type of instance can be used for ElastiCache?
What type of instance can be used for ElastiCache?
What is a common use case for ElastiCache?
What is a common use case for ElastiCache?
What is a limitation of ElastiCache?
What is a limitation of ElastiCache?
How is access to ElastiCache nodes controlled when deployed in a VPC?
How is access to ElastiCache nodes controlled when deployed in a VPC?
What is a characteristic of ElastiCache?
What is a characteristic of ElastiCache?
What is the main difference between Memcached and Redis engines in ElastiCache?
What is the main difference between Memcached and Redis engines in ElastiCache?
What is the billing model for ElastiCache?
What is the billing model for ElastiCache?
What is the purpose of maintenance windows in ElastiCache?
What is the purpose of maintenance windows in ElastiCache?
What is a limitation of ElastiCache Memcached?
What is a limitation of ElastiCache Memcached?
What is the maximum number of nodes per region for Memcached?
What is the maximum number of nodes per region for Memcached?
What is the purpose of Redis shards?
What is the purpose of Redis shards?
What is the primary purpose of Redis replication?
What is the primary purpose of Redis replication?
What is the difference between Lazy Loading and Write-Through caching strategies?
What is the difference between Lazy Loading and Write-Through caching strategies?
What is a key use case for ElastiCache?
What is a key use case for ElastiCache?
What happens when an existing ElastiCache Cluster is moved outside of a VPC?
What happens when an existing ElastiCache Cluster is moved outside of a VPC?
What is a characteristic of ElastiCache nodes?
What is a characteristic of ElastiCache nodes?
What metric is used to evaluate the efficiency of memory allocation in the Redis engine?
What metric is used to evaluate the efficiency of memory allocation in the Redis engine?
What is the recommended approach for addressing a high SwapUsage metric in ElastiCache Memcached?
What is the recommended approach for addressing a high SwapUsage metric in ElastiCache Memcached?
Which metric indicates the percentage of successful read-only key lookups in the Redis engine?
Which metric indicates the percentage of successful read-only key lookups in the Redis engine?
What is the primary purpose of Redis Auth?
What is the primary purpose of Redis Auth?
What is the recommended approach for handling an increasing number of CurrConnections in ElastiCache Memcached?
What is the recommended approach for handling an increasing number of CurrConnections in ElastiCache Memcached?
What is the primary purpose of AWS CloudTrail in relation to ElastiCache?
What is the primary purpose of AWS CloudTrail in relation to ElastiCache?
What is the recommended action if the Evictions metric exceeds a predefined threshold in ElastiCache Memcached?
What is the recommended action if the Evictions metric exceeds a predefined threshold in ElastiCache Memcached?
How is the pricing for ElastiCache calculated?
How is the pricing for ElastiCache calculated?
What is the recommended value for the MemoryFragmentationRatio metric in ElastiCache Redis?
What is the recommended value for the MemoryFragmentationRatio metric in ElastiCache Redis?
Which of the following metrics is unique to ElastiCache Redis, not found in Memcached?
Which of the following metrics is unique to ElastiCache Redis, not found in Memcached?
Study Notes
Overview of ElastiCache
- Fully managed service for Redis and Memcached in-memory data stores.
- Used to enhance latency and throughput for read-heavy and compute-intensive workloads.
- Ideal for Online Analytics Processing (OLAP) transactions.
- Operates on a push-button scalability model for memory, writes, and reads.
Access and Security
- ElastiCache nodes are accessible only through VPC security groups and subnet groups.
- Nodes cannot be accessed from the internet or EC2 instances in other VPCs.
- Access outside of VPC utilizes Cache Security Groups linked to EC2 Security Groups.
Node and Cluster Configuration
- A node is a fixed-size, network-attached RAM unit, running either Memcached or Redis.
- Each node has a unique DNS name and port, with automatic replacement for failed nodes.
- Nodes can be deployed in clusters, spanning multiple subnets within the same group.
Use Cases
- Commonly used for offloading reads from databases and storing computational results and session states.
- ElastiCache can manage on-demand or reserved instances but not Spot instances.
Memcached Features
- Simplistic model for large nodes and scaling capabilities.
- Multi-threaded, supporting 1-20 nodes per cluster and max 100 nodes per region.
- Lacks support for multi-AZ failover, replication, and snapshots.
- Ideal for caching database objects and integrating with features like SNS for notifications.
Redis Features
- Open-source and supports complex data structures, providing persistent data storage.
- Not multi-threaded; scales through shard addition rather than node addition.
- Offers automatic failover, master/slave replication, and multi-AZ redundancy.
- Supports snapshots for backups, allowing for data restoration.
Clustering Modes in Redis
- Disabled Clustering Mode:
- One shard can contain a primary node and multiple read-only replicas.
- Enabled Clustering Mode:
- Up to 15 shards, each with primary and read-only replicas; enables better scalability.
Failure Handling
- ElastiCache detects failures and promotes replicas with the lowest lag to primary status.
- DNS records are updated to point to the new primary node automatically.
Caching Strategies
- Lazy Loading: Load data into the cache only when it's requested.
- Write-Through: Updates data in the cache as it's written to the database, ensuring no stale data.
Monitoring and Metrics
- Memcached Metrics:
- CPU Utilization, Swap Usage, Evictions, and Current Connections provide insights into performance.
- Redis Metrics:
- Include Engine CPU Utilization, Memory Fragmentation Ratio, Cache Hits/Misses, and Current Connections.
Logging and Auditing
- Amazon ElastiCache actions are logged via AWS CloudTrail, tracking request identity and permissions.
- Redis supports authentication tokens to enhance security.
Pricing
- Charged per node-hour for each node type, with partial hours billed as full hours.
- No charges for data transfer between EC2 and ElastiCache within the same Availability Zone.
Key Distinctions between Memcached and Redis
- Memcached excels in simple object caching, while Redis offers more complex data structure support and persistence.
- Redis allows for fault tolerance through multi-AZ and replication features; Memcached does not support these capabilities.
Overview of ElastiCache
- Fully managed service for Redis and Memcached in-memory data stores.
- Used to enhance latency and throughput for read-heavy and compute-intensive workloads.
- Ideal for Online Analytics Processing (OLAP) transactions.
- Operates on a push-button scalability model for memory, writes, and reads.
Access and Security
- ElastiCache nodes are accessible only through VPC security groups and subnet groups.
- Nodes cannot be accessed from the internet or EC2 instances in other VPCs.
- Access outside of VPC utilizes Cache Security Groups linked to EC2 Security Groups.
Node and Cluster Configuration
- A node is a fixed-size, network-attached RAM unit, running either Memcached or Redis.
- Each node has a unique DNS name and port, with automatic replacement for failed nodes.
- Nodes can be deployed in clusters, spanning multiple subnets within the same group.
Use Cases
- Commonly used for offloading reads from databases and storing computational results and session states.
- ElastiCache can manage on-demand or reserved instances but not Spot instances.
Memcached Features
- Simplistic model for large nodes and scaling capabilities.
- Multi-threaded, supporting 1-20 nodes per cluster and max 100 nodes per region.
- Lacks support for multi-AZ failover, replication, and snapshots.
- Ideal for caching database objects and integrating with features like SNS for notifications.
Redis Features
- Open-source and supports complex data structures, providing persistent data storage.
- Not multi-threaded; scales through shard addition rather than node addition.
- Offers automatic failover, master/slave replication, and multi-AZ redundancy.
- Supports snapshots for backups, allowing for data restoration.
Clustering Modes in Redis
- Disabled Clustering Mode:
- One shard can contain a primary node and multiple read-only replicas.
- Enabled Clustering Mode:
- Up to 15 shards, each with primary and read-only replicas; enables better scalability.
Failure Handling
- ElastiCache detects failures and promotes replicas with the lowest lag to primary status.
- DNS records are updated to point to the new primary node automatically.
Caching Strategies
- Lazy Loading: Load data into the cache only when it's requested.
- Write-Through: Updates data in the cache as it's written to the database, ensuring no stale data.
Monitoring and Metrics
- Memcached Metrics:
- CPU Utilization, Swap Usage, Evictions, and Current Connections provide insights into performance.
- Redis Metrics:
- Include Engine CPU Utilization, Memory Fragmentation Ratio, Cache Hits/Misses, and Current Connections.
Logging and Auditing
- Amazon ElastiCache actions are logged via AWS CloudTrail, tracking request identity and permissions.
- Redis supports authentication tokens to enhance security.
Pricing
- Charged per node-hour for each node type, with partial hours billed as full hours.
- No charges for data transfer between EC2 and ElastiCache within the same Availability Zone.
Key Distinctions between Memcached and Redis
- Memcached excels in simple object caching, while Redis offers more complex data structure support and persistence.
- Redis allows for fault tolerance through multi-AZ and replication features; Memcached does not support these capabilities.
Overview of ElastiCache
- Fully managed service for Redis and Memcached in-memory data stores.
- Used to enhance latency and throughput for read-heavy and compute-intensive workloads.
- Ideal for Online Analytics Processing (OLAP) transactions.
- Operates on a push-button scalability model for memory, writes, and reads.
Access and Security
- ElastiCache nodes are accessible only through VPC security groups and subnet groups.
- Nodes cannot be accessed from the internet or EC2 instances in other VPCs.
- Access outside of VPC utilizes Cache Security Groups linked to EC2 Security Groups.
Node and Cluster Configuration
- A node is a fixed-size, network-attached RAM unit, running either Memcached or Redis.
- Each node has a unique DNS name and port, with automatic replacement for failed nodes.
- Nodes can be deployed in clusters, spanning multiple subnets within the same group.
Use Cases
- Commonly used for offloading reads from databases and storing computational results and session states.
- ElastiCache can manage on-demand or reserved instances but not Spot instances.
Memcached Features
- Simplistic model for large nodes and scaling capabilities.
- Multi-threaded, supporting 1-20 nodes per cluster and max 100 nodes per region.
- Lacks support for multi-AZ failover, replication, and snapshots.
- Ideal for caching database objects and integrating with features like SNS for notifications.
Redis Features
- Open-source and supports complex data structures, providing persistent data storage.
- Not multi-threaded; scales through shard addition rather than node addition.
- Offers automatic failover, master/slave replication, and multi-AZ redundancy.
- Supports snapshots for backups, allowing for data restoration.
Clustering Modes in Redis
- Disabled Clustering Mode:
- One shard can contain a primary node and multiple read-only replicas.
- Enabled Clustering Mode:
- Up to 15 shards, each with primary and read-only replicas; enables better scalability.
Failure Handling
- ElastiCache detects failures and promotes replicas with the lowest lag to primary status.
- DNS records are updated to point to the new primary node automatically.
Caching Strategies
- Lazy Loading: Load data into the cache only when it's requested.
- Write-Through: Updates data in the cache as it's written to the database, ensuring no stale data.
Monitoring and Metrics
- Memcached Metrics:
- CPU Utilization, Swap Usage, Evictions, and Current Connections provide insights into performance.
- Redis Metrics:
- Include Engine CPU Utilization, Memory Fragmentation Ratio, Cache Hits/Misses, and Current Connections.
Logging and Auditing
- Amazon ElastiCache actions are logged via AWS CloudTrail, tracking request identity and permissions.
- Redis supports authentication tokens to enhance security.
Pricing
- Charged per node-hour for each node type, with partial hours billed as full hours.
- No charges for data transfer between EC2 and ElastiCache within the same Availability Zone.
Key Distinctions between Memcached and Redis
- Memcached excels in simple object caching, while Redis offers more complex data structure support and persistence.
- Redis allows for fault tolerance through multi-AZ and replication features; Memcached does not support these capabilities.
Overview of ElastiCache
- Fully managed service for Redis and Memcached in-memory data stores.
- Used to enhance latency and throughput for read-heavy and compute-intensive workloads.
- Ideal for Online Analytics Processing (OLAP) transactions.
- Operates on a push-button scalability model for memory, writes, and reads.
Access and Security
- ElastiCache nodes are accessible only through VPC security groups and subnet groups.
- Nodes cannot be accessed from the internet or EC2 instances in other VPCs.
- Access outside of VPC utilizes Cache Security Groups linked to EC2 Security Groups.
Node and Cluster Configuration
- A node is a fixed-size, network-attached RAM unit, running either Memcached or Redis.
- Each node has a unique DNS name and port, with automatic replacement for failed nodes.
- Nodes can be deployed in clusters, spanning multiple subnets within the same group.
Use Cases
- Commonly used for offloading reads from databases and storing computational results and session states.
- ElastiCache can manage on-demand or reserved instances but not Spot instances.
Memcached Features
- Simplistic model for large nodes and scaling capabilities.
- Multi-threaded, supporting 1-20 nodes per cluster and max 100 nodes per region.
- Lacks support for multi-AZ failover, replication, and snapshots.
- Ideal for caching database objects and integrating with features like SNS for notifications.
Redis Features
- Open-source and supports complex data structures, providing persistent data storage.
- Not multi-threaded; scales through shard addition rather than node addition.
- Offers automatic failover, master/slave replication, and multi-AZ redundancy.
- Supports snapshots for backups, allowing for data restoration.
Clustering Modes in Redis
- Disabled Clustering Mode:
- One shard can contain a primary node and multiple read-only replicas.
- Enabled Clustering Mode:
- Up to 15 shards, each with primary and read-only replicas; enables better scalability.
Failure Handling
- ElastiCache detects failures and promotes replicas with the lowest lag to primary status.
- DNS records are updated to point to the new primary node automatically.
Caching Strategies
- Lazy Loading: Load data into the cache only when it's requested.
- Write-Through: Updates data in the cache as it's written to the database, ensuring no stale data.
Monitoring and Metrics
- Memcached Metrics:
- CPU Utilization, Swap Usage, Evictions, and Current Connections provide insights into performance.
- Redis Metrics:
- Include Engine CPU Utilization, Memory Fragmentation Ratio, Cache Hits/Misses, and Current Connections.
Logging and Auditing
- Amazon ElastiCache actions are logged via AWS CloudTrail, tracking request identity and permissions.
- Redis supports authentication tokens to enhance security.
Pricing
- Charged per node-hour for each node type, with partial hours billed as full hours.
- No charges for data transfer between EC2 and ElastiCache within the same Availability Zone.
Key Distinctions between Memcached and Redis
- Memcached excels in simple object caching, while Redis offers more complex data structure support and persistence.
- Redis allows for fault tolerance through multi-AZ and replication features; Memcached does not support these capabilities.
Overview of ElastiCache
- Fully managed service for Redis and Memcached in-memory data stores.
- Used to enhance latency and throughput for read-heavy and compute-intensive workloads.
- Ideal for Online Analytics Processing (OLAP) transactions.
- Operates on a push-button scalability model for memory, writes, and reads.
Access and Security
- ElastiCache nodes are accessible only through VPC security groups and subnet groups.
- Nodes cannot be accessed from the internet or EC2 instances in other VPCs.
- Access outside of VPC utilizes Cache Security Groups linked to EC2 Security Groups.
Node and Cluster Configuration
- A node is a fixed-size, network-attached RAM unit, running either Memcached or Redis.
- Each node has a unique DNS name and port, with automatic replacement for failed nodes.
- Nodes can be deployed in clusters, spanning multiple subnets within the same group.
Use Cases
- Commonly used for offloading reads from databases and storing computational results and session states.
- ElastiCache can manage on-demand or reserved instances but not Spot instances.
Memcached Features
- Simplistic model for large nodes and scaling capabilities.
- Multi-threaded, supporting 1-20 nodes per cluster and max 100 nodes per region.
- Lacks support for multi-AZ failover, replication, and snapshots.
- Ideal for caching database objects and integrating with features like SNS for notifications.
Redis Features
- Open-source and supports complex data structures, providing persistent data storage.
- Not multi-threaded; scales through shard addition rather than node addition.
- Offers automatic failover, master/slave replication, and multi-AZ redundancy.
- Supports snapshots for backups, allowing for data restoration.
Clustering Modes in Redis
- Disabled Clustering Mode:
- One shard can contain a primary node and multiple read-only replicas.
- Enabled Clustering Mode:
- Up to 15 shards, each with primary and read-only replicas; enables better scalability.
Failure Handling
- ElastiCache detects failures and promotes replicas with the lowest lag to primary status.
- DNS records are updated to point to the new primary node automatically.
Caching Strategies
- Lazy Loading: Load data into the cache only when it's requested.
- Write-Through: Updates data in the cache as it's written to the database, ensuring no stale data.
Monitoring and Metrics
- Memcached Metrics:
- CPU Utilization, Swap Usage, Evictions, and Current Connections provide insights into performance.
- Redis Metrics:
- Include Engine CPU Utilization, Memory Fragmentation Ratio, Cache Hits/Misses, and Current Connections.
Logging and Auditing
- Amazon ElastiCache actions are logged via AWS CloudTrail, tracking request identity and permissions.
- Redis supports authentication tokens to enhance security.
Pricing
- Charged per node-hour for each node type, with partial hours billed as full hours.
- No charges for data transfer between EC2 and ElastiCache within the same Availability Zone.
Key Distinctions between Memcached and Redis
- Memcached excels in simple object caching, while Redis offers more complex data structure support and persistence.
- Redis allows for fault tolerance through multi-AZ and replication features; Memcached does not support these capabilities.
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Description
Learn about Amazon ElastiCache, a web service that provides in-memory data stores for Redis and Memcached protocols, improving latency and throughput for read-heavy workloads.