Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions,
see Getting Started with Amazon Web Services in China
(PDF).
Identify your unused resources to optimize costs in Amazon Keyspaces
This section provides an overview of how to evaluate your unused resources regularly. As
your application requirements evolve, you should ensure no resources are unused and contributing
to unnecessary Amazon Keyspaces costs. The procedures described below use Amazon CloudWatch metrics to identify
unused resources and take action to reduce costs.
You can monitor Amazon Keyspaces using CloudWatch, which collects and processes raw data from Amazon Keyspaces into
readable, near real-time metrics. These statistics are retained for a period of time, so that
you can access historical information to better understand your utilization. By default, Amazon Keyspaces
metric data is sent to CloudWatch automatically. For more information, see What is Amazon CloudWatch? and
Metrics
retention in the Amazon CloudWatch User Guide.
How to identify unused
resources
To identify unused tables you can take a look at the following CloudWatch metrics over a
period of 30 days to understand if there are any active reads or writes on a specific table:
ConsumedReadCapacityUnits
The number of read capacity units consumed over the specified time period, so you can
track how much consumed capacity you have used. You can retrieve the total consumed read
capacity for a table.
ConsumedWriteCapacityUnits
The number of write capacity units consumed over the specified time period, so you can
track how much consumed capacity you have used. You can retrieve the total consumed write
capacity for a table.
Identifying unused table
resources
Amazon CloudWatch is a monitoring and observability service which provides the Amazon Keyspaces table metrics
you can use to identify unused resources. CloudWatch metrics can be viewed through the Amazon Web Services Management Console
as well as through the Amazon Command Line Interface.
- Amazon Command Line Interface
-
To view your tables metrics through the Amazon Command Line Interface, you can use the following
commands.
-
First, evaluate your table's reads:
If the table name is not unique within your account,
you must also specify the name of the keyspace.
aws cloudwatch get-metric-statistics --metric-name
ConsumedReadCapacityUnits --start-time <start-time> --end-time <end-
time> --period <period> --namespace AWS/Cassandra --statistics Sum --
dimensions Name=TableName,Value=<table-name>
To avoid falsely identifying a table as unused, evaluate metrics over a longer
period. Choose an appropriate start-time and end-time range, such as
30 days, and an appropriate period, such as 86400.
In the returned data, any Sum above 0 indicates that the table you are evaluating received read
traffic during that period.
The following result shows a table receiving read traffic in the evaluated
period:
{
"Timestamp": "2022-08-25T19:40:00Z",
"Sum": 36023355.0,
"Unit": "Count"
},
{
"Timestamp": "2022-08-12T19:40:00Z",
"Sum": 38025777.5,
"Unit": "Count"
},
The following result shows a table not receiving read traffic in the evaluated
period:
{
"Timestamp": "2022-08-01T19:50:00Z",
"Sum": 0.0,
"Unit": "Count"
},
{
"Timestamp": "2022-08-20T19:50:00Z",
"Sum": 0.0,
"Unit": "Count"
},
-
Next, evaluate your table’s writes:
aws cloudwatch get-metric-statistics --metric-name
ConsumedWriteCapacityUnits --start-time <start-time> --end-time <end-
time> --period <period> --namespace AWS/Cassandra --statistics Sum --
dimensions Name=TableName,Value=<table-name>
To avoid falsely identifying a table as unused, you will want to evaluate
metrics over a longer period. Choose an appropriate start-time and end-time range,
such as 30 days, and an appropriate period, such as
86400.
In the returned data, any Sum above 0 indicates that the table you are evaluating received read
traffic during that period.
The following result shows a table receiving write traffic in the evaluated
period:
{
"Timestamp": "2022-08-19T20:15:00Z",
"Sum": 41014457.0,
"Unit": "Count"
},
{
"Timestamp": "2022-08-18T20:15:00Z",
"Sum": 40048531.0,
"Unit": "Count"
},
The following result shows a table not receiving write traffic in the evaluated
period:
{
"Timestamp": "2022-07-31T20:15:00Z",
"Sum": 0.0,
"Unit": "Count"
},
{
"Timestamp": "2022-08-19T20:15:00Z",
"Sum": 0.0,
"Unit": "Count"
},
- Amazon Web Services Management Console
-
The following steps allow you to evaluate your resource utilization through
the Amazon Web Services Management Console.
-
Log into the Amazon Web Services Management Console and navigate to the CloudWatch service page at
https://console.amazonaws.cn/cloudwatch/. Select the appropriate Amazon Web Services Region in the top right of
the console, if necessary.
-
On the left navigation bar, locate the Metrics section and choose
All metrics.
-
The action above opens a dashboard with two panels. In the top panel, you
can see currently graphed metrics. On the bottom you can select the metrics
available to graph. Choose Amazon Keyspaces in the bottom panel.
-
In the Amazon Keyspaces metrics selection panel, choose the Table
Metrics category to show the metrics for your tables in the current
region.
-
Identify your table name by scrolling down the menu, then choose the metrics
ConsumedReadCapacityUnits and ConsumedWriteCapacityUnits
for your table.
-
Choose the Graphed metrics (2) tab and adjust
the Statistic column to Sum.
-
To avoid falsely identifying a table as unused, evaluate the table metrics
over a longer period. At the top of the graph panel, choose an appropriate time
frame, such as 1 month, to evaluate your table. Choose Custom, choose 1 Months in the
drop-down menu, and choose Apply.
-
Evaluate the graphed metrics for your table to determine if it is being used.
Metrics that have gone above 0 indicate that a
table has been used during the evaluated time period. A flat graph at 0 for both read and write indicates that a table is
unused.
Cleaning up unused table
resources
If you have identified unused table resources, you can reduce their ongoing costs in the
following ways.
If you have identified an unused table but would still like to keep it available in case
it needs to be accessed in the future, consider switching it to on-demand mode. Otherwise,
you can consider deleting the table.
Capacity modes
Amazon Keyspaces charges for reading, writing, and storing data in your Amazon Keyspaces tables.
Amazon Keyspaces has two capacity modes, which
come with specific billing options for processing reads and writes on your tables: on-demand
and provisioned. The read/write capacity mode controls how you are charged for read and write
throughput and how you manage capacity.
For on-demand mode tables, you don't need to specify how much read and write throughput
you expect your application to perform. Amazon Keyspaces charges you for the reads and writes that your
application performs on your tables in terms of read request units and write request units. If
there is no activity on your table, you do not pay for throughput but you still incur
a storage charge.
Deleting tables
If you’ve discovered an unused table and would like to delete it, consider to make a
backup or export the data first.
Backups taken through Amazon Backup can leverage cold storage tiering, further reducing
cost. Refer to the Managing backup plans
documentation for information on how to use a lifecycle to move your backup to cold
storage.
After your table has been backed up, you may choose to delete it either through the
Amazon Web Services Management Console or through the Amazon Command Line Interface.
Cleaning up unused
point-in-time recovery (PITR) backups
Amazon Keyspaces offers Point-in-time recovery, which provides continuous backups for
35 days to help you protect against accidental writes or deletes. PITR backups have costs
associated with them.
Refer to the documentation at Point-in-time recovery for Amazon Keyspaces (for Apache Cassandra) to determine if your
tables have backups enabled that may no longer be needed.