RDS Instance Type - General purpose and Memory optimized
All the AWS database service RDS instances types come up with varying combinations of CPU, memory, storage, and networking capacity. Finding the best database instance type might be a bit tricky if you don’t know them and for what use.
- “General purpose database instances provide a balance of compute, memory and networking resources, and can be used for a variety of diverse workloads”. It’s a good choice for many database workloads including small and mid-size databases.
General Purpose
Type
t2 (tiny or turbo)
m4 (medium)
Description
CPU Burstable Performance
High frequency Intel Xeon processors
2,3 Ghz Intel Xeon E5-2686 v4 (Brodwell) processors or 2,4 GHz Intel Xeon E5-2676 v3 (Haswell) processors
EBS-optimized by default without additional cost
Support for Enhanced Networking
You might also look for the latest generation of General Purpose Instance:
General Purpose (Latest)
Type
t3 (over T2)
m5 (over M4)
Description
CPU Burstable Performance
High frequency Intel Xeon processors
EBS Optimized
Support for Enhanced Networking
Powered by AWS Nitro System
Unlimited mode to ensure performance during peak periods
2,5 GHz Intel Xeon Platinum 8175 processors
EBS-optimized by default without additional cost
Support for Enhanced Networking (up to 25 gbps network bandwidth)
- “Memory optimized instances are designed to deliver fast performance for workloads that process large data sets in memory”. It’s a good choice for memory-intensive database workloads at a larger scale.
Memory Optimized
Type
r4 (RAM)
x1e (xtreme)
Description
High Frequency Intel Xeon E5-2686 v4 (Broadwell) processor
Optimized for memory-intensive applications
EBS Optimized
Support for Enhanced Networking
High Frequency Intel Xeon E7-8880 v3 (Haswelll) processor
EBS Optimized
Support for Enhanced Networking
Optimized for high-performance databases, memory-intensive databases, and other memory-intensive applications
You might also look for the latest generation of Memory Optimized Instance:
Memory Optimized
Type
r5
z1d
Description
High Frequency Intel Xeon Platinum 8000 series processor with sustained all core Turbo CPU clock speed of up to 3.1 GHz
EBS optimized
Support for Enhanced Networking
High Frequency Intel Xeon processor
EBS Optimized
Support for Enhanced Networking
Optimized for high-performance databases, memory-intensive databases, and other memory-intensive applications
AWS RDS Instance Features
For each of your AWS RDS Instances, you might want to wrap some metrics around the following topic:
- CPU / RAM consumption
- Network traffic
- Disk space consumption
- Database connections
- IOPS metrics
Let’s dig into it!
CPU / RAM consumption
For your RDS instance:
Name
Description
Unit
CloudWatch Namespace
CPUUtilization
Percentage of CPU utilization
Percent
RDS
For your RDS burstable performance instances:
Name
Description
Units
CloudWatch Namespace
CPUCreditUsage
( T2 Instances)
Number of CPU credits spent by the instance for CPU utilization
Credits (vCPU-minutes)
RDS
CPUCreditBalance
( T2 Instances)
Number of earned CPU credits that an instance has accrued since it was launched or started
Credits (vCPU-minutes)
RDS
BurstBalance (gp2)
The percent of General Purpose SSD (gp2) burst-bucket I/O credits available.
Percent
RDS
Network traffic CloudWatch Metrics
Name
Description
Units
CloudWatch Namespace
NetworkReceiveThroughput
Number of bytes received on all network interfaces by the instance
Bytes/Second
RDS
NetworkTransmitThroughput
Number of bytes sent out on all network interfaces by the instance.
Bytes/Second
RDS
Disk Space Consumption CloudWatch Metrics
Name
Description
Units
CloudWatch Namespace
FreeStorageSpace
The amount of available storage space
Bytes
RDS
WriteIOPS
The average number of disk write I/O operations per second (write iops).
Count/Second
RDS
Database connections CloudWatch Metrics
Name
Description
Units
CloudWatch Namespace
DatabaseConnections
The number of database connections in use.
Count
RDS
FreeableMemory
The amount of available random access memory
Bytes
RDS
NetworkReceiveThroughput
The incoming (Receive) network traffic on the DB instance, including both customer database traffic and Amazon RDS traffic used for monitoring and replication.
Bytes/Second
RDS
NetworkTransmitThroughput
The outgoing (Transmit) network traffic on the DB instance, including both customer database traffic and Amazon RDS traffic used for monitoring and replication
Bytes/Second
RDS
IOPS CloudWatch Metrics
Name
Description
Units
CloudWatch Namespace
ReadIOPS
The average number of disk read I/O operations per second.
Count/Second
RDS
WriteIOPS
The average number of disk write I/O operations per second.
Count/Second
RDS
DiskQueueDepth
The number of outstanding IOs (read/write requests) waiting to access the disk
Count/Second
RDS
ReadLatency
The average amount of time taken per disk I/O operation.
Seconds
RDS
WriteLatency
The average amount of bytes written to disk per second.
Bytes/Second
RDS
Going deeper, the enhanced monitoring: Monitor your processes
Launched in 2016, RDS Enhanced Monitoring is a feature that enables customers to send amazon rds metrics to cloudwatch from their database server’s operating system. It allows you to get some RDS server performance insights.
By default, CloudWatch gathers metrics about CPU utilization from the hypervisor when Enhanced Monitoring gathers its metrics from an agent directly on the instance. Enhanced Monitoring is particularly useful when you want to see how different processes or threads on your DB instance use the CPU.
You can enable this option directly on your DB instance when:
- You create a DB → In the Configure Advanced Settings page (with the amazon rds console) or through parameters (with terraform)
- You create a Read Replica → In the Configure Advanced Settings page (in aws console) or through your terraform code (through a parameter).
- You modify a DB Instance → In the Modify DB Instance page or through your terraform code (which will update your DB).
For your Enhanced Monitoring you’ll need:
- Set the Monitoring Role property to the IAM role that you created to permit Amazon RDS to communicate with CloudWatch for you (or either choose Default to have RDS create this role for you)
- Set the Granularity property to the interval chosen (1, 5, 10, 15, 30 or 60 seconds)
Enabling enhanced monitoring will show the following Process list on your RDS instance:
- RDS child processes - A summary of RDS processes that support the DB instance.
- RDS processes - A summary of the resources used by the RDS management agent, diagnostics monitoring processes and other AWS processes that are required to support RDS DB instances.
- OS processes -A summary of the kernel and system processes (which have a low impact on performance).
It is also available through CloudWatch, through the Logs section in the navigation pane, you need to select RDSOSMetrics from the list of log groups and then select your desired log stream. It’s based on the following groups:
- general - Global information about the DB instance.
- cpuUtilization - CPU and its uses by the DB instance logs.
- fileSys - File-system logs.
- loadAverageMinute - Number of processes requesting CPU time.
- memory - Memory logs
- network - Network interface and bytes received/uploaded logs
- processList - CPU, memory used by the processes logs
- swap - Swap memory logs
- tasks - Tasks logs
Find more information about EC2 CloudWatch Metrics and EBS CloudWatch metrics in those two blog posts.
You may check what is best for your workflow now that you understand better RDS types, and which metrics are important to monitor.
