diff --git a/knowledge base/cloud computing/aws/rds.md b/knowledge base/cloud computing/aws/rds.md index 8c6b0bd..d6469c8 100644 --- a/knowledge base/cloud computing/aws/rds.md +++ b/knowledge base/cloud computing/aws/rds.md @@ -27,6 +27,7 @@ 1. [Cancel pending modifications](#cancel-pending-modifications) 1. [Pricing](#pricing) 1. [Cost-saving measures](#cost-saving-measures) + 1. [Reserved DB instances](#reserved-db-instances) 1. [Troubleshooting](#troubleshooting) 1. [ERROR: extension must be loaded via shared\_preload\_libraries](#error-extension-must-be-loaded-via-shared_preload_libraries) 1. [ERROR: must be superuser to alter _X_ roles or change _X_ attribute](#error-must-be-superuser-to-alter-x-roles-or-change-x-attribute) @@ -1074,14 +1075,8 @@ Impacting factors (from most to least impactful): - Choose _appropriate_ instance types and sizes.
Consider changing them more appropriate ones (more recent, smaller, or Graviton-based) every few months. -- Consider leveraging [reserved instances][rds reserved instances]. - - Prefer using _Standard_ RIs when sticking with one instance type and **not** needing changing it for the **entire** - duration of a reservation.
- Otherwise, prefer _Convertible_ (A.K.A. _Size-flexible_) RIs for flexibility. - +- Consider leveraging [reserved DB instances].
RDS does **not** support Savings Plans at the time of writing. - - Optimize storage. - Set backup retention periods that balance recovery needs and storage costs. - Regularly delete unnecessary manual snapshots. @@ -1089,6 +1084,84 @@ Impacting factors (from most to least impactful): - Prefer disabling Extended support for an instance when not necessary (e.g., for development or testing DBs).
Keep the DBs' engine versions updated to stay out of the Extended support otherwise. +#### Reserved DB instances + +Refer [Reserved DB instances for Amazon RDS]. + +DB instances can be reserved for one- or three-year terms.
+Reserved DB instances provide significant discount compared to on-demand DB instance pricing.
+Discounts for reserved DB instances are tied to instance type and AWS Region. + +Once one buys reservations, the discount applies to DB instances that have the same specifications as the reservation +for **all** the following: + +- AWS Region. +- DB engine (but not the DB engine's **version**). +- DB instance type. +- DB instance size (`RDS` for Db2, SQL Server, and Oracle License Included). +- Edition (`RDS` for Db2, SQL Server, and Oracle). +- License type (`license-included` or `bring-your-own-license`). + +DB instances **not** matching the reservations' specifics are billed at the on-demand rate. + +DB instances using reservations can be modified. Part of all of the discount is applied as long as those changes are +within the reservations' specifications.
+Should the changes fall outside of the reservations's specifications, such as changing the instance class, the discount +no longer applies. + +Reservations are available in three varieties: + +- _No Upfront_: bills a discounted hourly rate for every hour within the term, regardless of usage, and requiring no + upfront payment.
Only available as one-year reservations. +- _Partial Upfront_: part of the reserved DB instance is paid upfront; the remaining hours in the term are billed at a + discounted hourly rate, regardless of usage. +- _All Upfront_: the full payment is made at the start of the term, with no other costs incurred for the remainder of + the term regardless of the number of hours used. + +> [!note] +> Not all RDS instance classes support all Reserved DB Instance offering types.
+> Review the Reserved DB Instance offerings in the Management Console or using the +> `describe-reserved-db-instances-offerings` CLI command to confirm availability. + +When using consolidated billing, all AWS accounts in the organization are treated as a single account.
+This means that **all** accounts in the organization can receive the hourly cost benefit of reserved DB instances that +are purchased in any other account. + +When purchasing DB instance reservations, one of the specifications to give is the instance class.
+The discount is automatically applied to DB instances using **any size** of that class, meaning that the instance _can_ +be scaled up and down as long as the instance class remains the same.
+For example, a reservation for a `db.r6i.large` can apply to a `db.r6i.xlarge` because the instance class is the same +(`db.r6i`), but not to a `db.r6id.large` or `db.r7g.large` because the class type would change. + +> [!warning] +> Size-flexible reserved DB instances are only available for DB instances residing within the same AWS Region and using +> the same database engine. + +Usage for different reserved DB instance sizes is calculated as _normalized units per hour_.
+For example, one unit of usage on 2x `db.r3.large` DB instances is equivalent to 8x normalized units per hour of usage +on one `db.r3.small`.
+Refer the table on [Reserved DB instances for Amazon RDS] to get the number of normalized units per hour for each DB +instance size. + +DB instance reservation benefits apply to both Multi-AZ and Single-AZ configurations as long as the DB instance class +type remains the same.
+Multi-AZ configurations just consume normalized units per hour for each extra AZ.
+For example, one can move from a Single-AZ deployment running on one large DB instance to a Multi-AZ deployment running +on a medium DB instance per AZ an consume the same amount of units per hour. + +Size flexibility does **not** apply to RDS for SQL Server and RDS for Oracle License Included. + +DB instance reservations do **not** provide discounts for the costs associated with storage, backups, and I/O.
+It does provide a discount only on the hourly, on-demand instance usage. + +The terms for a reserved DB instance involve a one-year or three-year commitment.
+One **cannot** cancel a reservation before the commitment ends. They are billed for the upfront costs regardless of +whether they use the resources. + +Should one delete a DB instance that is covered by a reserved DB instance discount, they can launch another DB instance +with compatible specifications. In this case, the discounted rate is automatically applied to the new instance during +the reservation term. + ## Troubleshooting ### ERROR: extension must be loaded via shared_preload_libraries @@ -1204,6 +1277,7 @@ or write workloads and exceeds the instance type quotas. [Exporting snapshots to S3]: #exporting-snapshots-to-s3 +[Reserved DB instances]: #reserved-db-instances [Storage optimization]: #storage-optimization @@ -1230,9 +1304,9 @@ or write workloads and exceeds the instance type quotas. [Multi-AZ DB instance deployments for Amazon RDS]: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.MultiAZSingleStandby.html [pricing and data retention for performance insights]: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_PerfInsights.Overview.cost.html [RDS pricing]: https://aws.amazon.com/rds/pricing/ -[RDS reserved instances]: https://aws.amazon.com/rds/reserved-instances/ [Recommended alarms for RDS]: https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Best_Practice_Recommended_Alarms_AWS_Services.html#RDS -[renaming a db instance]: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_RenameInstance.html +[Renaming a DB instance]: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_RenameInstance.html +[Reserved DB instances for Amazon RDS]: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_WorkingWithReservedDBInstances.html [Restoring a DB instance to a specified time for Amazon RDS]: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_PIT.html [restoring from a db snapshot]: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_RestoreFromSnapshot.html [Stopping an Amazon RDS DB instance temporarily]: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_StopInstance.html