# Managing nodes A node is the smallest building block of a MemoryDB deployment. A node belongs to a shard which belongs to a cluster. Each node runs the engine version that was chosen when the cluster was created or last modified. Each node has its own Domain Name Service (DNS) name and port. Multiple types of MemoryDB nodes are supported, each with varying amounts of associated memory and computational power. **Topics** + [MemoryDB nodes and shards](nodes.nodegroups.md) + [Supported node types](nodes.supportedtypes.md) + [MemoryDB reserved nodes](nodes.reservednodes.md) + [Replacing nodes](nodes.nodereplacement.md) Important operations involving nodes include: + [Adding / Removing nodes from a cluster](clusters.deletenode.md) + [Scaling](scaling.md) + [Finding connection endpoints](endpoints.md) # MemoryDB nodes and shards A shard is a hierarchical arrangement of nodes, each wrapped in a cluster. Shards support replication. Within a shard, one node functions as the read/write primary node. All the other nodes in a shard function as read-only replicas of the primary node. MemoryDB supports multiple shards within a cluster. This support enables partitioning of your data in a MemoryDB cluster. MemoryDB supports replication via shards. The API operation [DescribeClusters](https://docs.aws.amazon.com/memorydb/latest/APIReference/API_DescribeClusters.html) lists the shards with the member nodes, the node names, endpoints and also other information. After a MemoryDB cluster is created, it can be altered (scaled in or out). For more information, see [Scaling](scaling.md) and [Replacing nodes](nodes.nodereplacement.md). When you create a new cluster, you can seed it with data from the old cluster so it doesn't start out empty. Doing this can be helpful if you need change your node type, engine version or migrate from Amazon ElastiCache (Redis OSS). For more information, see [Making manual snapshots](snapshots-manual.md) and [Restoring from a snapshot](snapshots-restoring.md). # Supported node types MemoryDB supports the following node types. **Memory optimized** | Instance type | Baseline bandwidth (Gbps) | Burst bandwidth (Gbps) | Enhanced I/O Multiplexing (Valkey 7.2 and Redis OSS 7.0.4\$1) | Minimum engine version | | --- | --- | --- | --- | --- | | db.r7g.large | 0.937 | 12.5 | No | 6.2 | | db.r7g.xlarge | 1.876 | 12.5 | No | 6.2 | | db.r7g.2xlarge | 3.75 | 15 | Yes | 6.2 | | db.r7g.4xlarge | 7.5 | 15 | Yes | 6.2 | | db.r7g.8xlarge | 15 | N/A | Yes | 6.2 | | db.r7g.12xlarge | 22.5 | N/A | Yes | 6.2 | | db.r7g.16xlarge | 30 | N/A | Yes | 6.2 | | db.r6g.large | 0.75 | 10.0 | No | 6.2 | | db.r6g.xlarge | 1.25 | 10.0 | No | 6.2 | | db.r6g.2xlarge | 2.5 | 10.0 | Yes | 6.2 | | db.r6g.4xlarge | 5.0 | 10.0 | Yes | 6.2 | | db.r6g.8xlarge | 12 | N/A | Yes | 6.2 | | db.r6g.12xlarge | 20 | N/A | Yes | 6.2 | | db.r6g.16xlarge | 25 | N/A | Yes | 6.2 | **Memory optimized with data tiering** | Instance type | Baseline bandwidth (Gbps) | Burst bandwidth (Gbps) | Enhanced I/O Multiplexing (Valkey 7.2 and Redis OSS 7.0.4\$1) | Minimum engine version | | --- | --- | --- | --- | --- | | db.r6gd.xlarge | 1.25 | 10 | No | 6.2 | | db.r6gd.2xlarge | 2.5 | 10 | No | 6.2 | | db.r6gd.4xlarge | 5.0 | 10 | No | 6.2 | | db.r6gd.8xlarge | 12 | N/A | No | 6.2 | **General purpose nodes** | Instance type | Baseline bandwidth (Gbps) | Burst bandwidth (Gbps) | Enhanced I/O Multiplexing (Valkey 7.2 and Redis OSS 7.0.4\$1) | Minimum engine version | | --- | --- | --- | --- | --- | | db.t4g.small | 0.128 | 5.0 | No | 6.2 | | db.t4g.medium | 0.256 | 5.0 | No | 6.2 | For AWS Region availability, see [MemoryDB Pricing](https://aws.amazon.com/memorydb/pricing/) All node types are created in a virtual private cloud (VPC). # MemoryDB reserved nodes Reserved nodes provide you with a significant discount compared to on-demand node pricing. Reserved nodes are not physical nodes, but rather a billing discount applied to the use of on-demand nodes in your account. Discounts for reserved nodes are tied to node type and AWS Region. **Note** All current MemoryDB reserved nodes are based on the pricing for and provide coverage for nodes running the Redis OSS engine. These reserved nodes can be applied to the Valkey engine as documented in [Size flexible reserved nodes](reserved-nodes-size.md), but Valkey-specific reserved nodes are not available. The general process for working with reserved nodes is as follows: + Review information about available reserved node offerings + Purchase a reserved node offering using the AWS Management Console, AWS Command Line Interface or SDK + Review information about your existing reserved nodes **Topics** + [Overview of reserved nodes](reserved-nodes-overview.md) + [Offering types](reserved-nodes-offerings.md) + [Size flexible reserved nodes](reserved-nodes-size.md) + [Upgrading nodes from Redis OSS to Valkey](reserved-nodes.md) + [Deleting a reserved node](reserved-nodes-deleting.md) + [Working with reserved nodes](reserved-nodes-working-with.md) # Overview of reserved nodes When you purchase a MemoryDB reserved node, you purchase a commitment to getting a discounted rate, on a specific node type, for the duration of the reserved node. To use a MemoryDB reserved node, you create a new node just like you do for an on-demand node. The new node that you create must match the specifications of the reserved node. If the specifications of the new node match an existing reserved node for your account, you are billed at the discounted rate offered for the reserved node. Otherwise, the node is billed at an on-demand rate. You can use the AWS Management Console, the AWS CLI, or the MemoryDB API to list and purchase available reserved node offerings. MemoryDB offers reserved nodes for the memory optimized R7g, R6g, and R6gd (with data tiering) nodes. For pricing information, see [MemoryDB Pricing](https://aws.amazon.com/memorydb/pricing/ ). # Offering types Reserved nodes are available in three varieties – No Upfront, Partial Upfront, and All Upfront – that let you optimize your MemoryDB costs based on your expected usage. **No Upfront ** – This option provides access to a reserved node without requiring an upfront payment. Your No Upfront reserved node bills a discounted hourly rate for every hour within the term, regardless of usage, and no upfront payment is required. **Partial Upfront** – This option requires a part of the reserved node to be paid upfront. The remaining hours in the term are billed at a discounted hourly rate, regardless of usage. **All Upfront** – 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. All three offering types are available in one-year and three-year terms. # Size flexible reserved nodes When you purchase a reserved node, one thing that you specify is the node type, for example db.r6g.xlarge. For more information, about node types, see [MemoryDB Pricing](https://aws.amazon.com/memorydb/pricing/ ). If you have a node, and you need to scale it to larger capacity, your reserved node is automatically applied to your scaled node. That is, your reserved nodes are automatically applied to usage of any size in the same node family. Size-flexible reserved nodes are available for nodes with the same AWS Region. Size-flexible reserved nodes can only scale in their node families. For example, a reserved node for a db.r6g.xlarge can apply to a db.r6g.2xlarge, but not to a db.r6gd.large, because db.r6g and db.r6gd are different node families. Size flexibility means that you can move freely between configurations within the same node family. For example, you can move from a r6g.xlarge reserved node (8 normalized units) to two r6g.large reserved nodes (8 normalized units) (2\$14 = 8 normalized units) in the same AWS Region at no extra cost. You can compare usage for different reserved node sizes by using normalized units. For example, one hour of usage on two db.r6g.4xlarge nodes is equivalent to 16 hours of usage on one db.r6g.large. The following table shows the number of normalized units for each node size: **** | Node size | Normalized units (Redis OSS) | Normalized units (Valkey) | | --- | --- | --- | | small | 1 | .7 | | medium | 2 | 1.4 | | large | 4 | 2.8 | | xlarge | 8 | 5.6 | | 2xlarge | 16 | 11.2 | | 4xlarge | 32 | 22.4 | | 6xlarge | 48 | 33.6 | | 8xlarge | 64 | 44.8 | | 10xlarge | 80 | 56 | | 12xlarge | 96 | 67.2 | | 16xlarge | 128 | 89.6 | | 24xlarge | 192 | 134.4 | For example, you purchase a db.r6gd.xlarge reserved node, and you have two running db.r6gd.large reserved nodes in your account in the same AWS Region. In this case, the billing benefit is applied in full to both nodes. ![\[Diagram showing two running reserved nodes with billing benefit applied to both nodes.\]](http://docs.aws.amazon.com/memorydb/latest/devguide/images/ri1.png) Alternatively, if you have one db.r6gd.2xlarge instance running in your account in the same AWS Region, the billing benefit is applied to 50 percent of the usage of the reserved node. ![\[Diagram showing one instance with billing benefit applied to 50 percent of the usage of the reserved node.\]](http://docs.aws.amazon.com/memorydb/latest/devguide/images/ri2.png) # Upgrading nodes from Redis OSS to Valkey With the launch of Valkey in MemoryDB, you can now apply your Redis OSS reserved node discount to the Valkey engine. You can upgrade from Redis OSS to Valkey while still benefitting from existing contracts and reservations. In addition to being able to apply your benefits within the node family and engine, you can even receive more incremental value. Valkey is priced at a 30% discount relative to Redis OSS, and with reserved node flexibility, you can use your Redis OSS reserved nodes to cover more running Valkey nodes. To calculate the discounted rate, each MemoryDB node and engine combination has a normalization factor that's measured in units. Reserved node units can be applied to any running node within the reserved node's instance family for a given engine. Redis OSS reserved nodes can additionally apply across engines to cover running Valkey nodes. Because Valkey is priced at a discount relative to Redis OSS, its units for a given instance type are lower, which allows a Redis OSS reserved node to cover more Valkey nodes. As an example, let's say you have purchased a reserved node for a db.r7g.4xlarge for the Redis OSS engine (32 units) and are running one db.r7g.4xlarge Redis OSS node (32 units). If you upgrade the node to Valkey, the normalization factor of the running node drops to 22.4 units, and your existing reserved node provides you with an additional 9.6 units to use against any other running Valkey or Redis OSS node within the db.r7g family in the Region. You could use this to cover 42% of another db.r7g.4xlarge Valkey node in the account (22.4 units), or 100% of a db.r7g.xlarge Valkey node (5.6 units) and 100% of a db.r7g.large Valkey node (2.8 units). # Deleting a reserved node The terms for a reserved node involve a one-year or three-year commitment. You can't cancel a reserved node. However, you can delete a node that is covered by a reserved node discount. The process for deleting a node that is covered by a reserved node discount is the same as for any other node. If you delete a node that is covered by a reserved node discount, you can launch another node with compatible specifications. In this case, you continue to get the discounted rate during the reservation term (one or three years). # Working with reserved nodes You can use the AWS Management Console, the AWS Command Line Interface, and MemoryDB API to work with reserved nodes. ## Console **To get pricing and information about available reserved node offerings** 1. Sign in to the AWS Management Console and open the MemoryDB console at [https://console.aws.amazon.com/memorydb/](https://console.aws.amazon.com/memorydb/). 1. In the navigation pane, choose **Reserved nodes**. 1. Choose **Purchase reserved nodes**. 1. For **Node type**, choose the type of node you want to be deployed. 1. For **Quantity**, choose the number of nodes you want to deploy. 1. For **Term**, choose the length of time you want the database node reserved. 1. For **Offering type**, choose the offering type. After you make these selections, you can see the pricing information under **Reservation summary**. **Important** Choose **Cancel** to avoid purchasing these reserved nodes and incurring any charges. After you have information about the available reserved node offerings, you can use the information to purchase an offering as shown in the following procedure: **To purchase a reserved node** 1. Sign in to the AWS Management Console and open the MemoryDB console at [https://console.aws.amazon.com/memorydb/](https://console.aws.amazon.com/memorydb/). 1. In the navigation pane, choose **Reserved nodes**. 1. Choose **Purchase reserved nodes**. 1. For **Node type**, choose the type of node you want to be deployed. 1. For **Quantity**, choose the number of nodes you want to deploy. 1. For **Term**, choose the length of time you want the database node reserved. 1. For **Offering type**, choose the offering type. 1. (Optional) You can assign your own identifier to the reserved nodes that you purchase to help you track them. For **Reservation ID**, type an identifier for your reserved node. After you make these selections, you can see the pricing information under **Reservation summary**. 1. Choose **Purchase reserved nodes**. 1. Your reserved nodes are purchased, then displayed in the **Reserved nodes** list. **To get information about reserved nodes for your AWS account** 1. Sign in to the AWS Management Console and open the MemoryDB console at [https://console.aws.amazon.com/memorydb/](https://console.aws.amazon.com/memorydb/). 1. In the navigation pane, choose **Reserved nodes**. 1. The reserved nodes for your account appear. To see detailed information about a particular reserved node, choose that node in the list. You can then see detailed information about that node in the detail. ## AWS Command Line Interface The following `describe-reserved-nodes-offerings` example returns details of reserved-node offerings. ``` aws memorydb describe-reserved-nodes-offerings ``` This produces output similar to the following: ``` { "ReservedNodesOfferings": [ { "ReservedNodesOfferingId": "0193cc9d-7037-4d49-b332-xxxxxxxxxxxx", "NodeType": "db.xxx.large", "Duration": 94608000, "FixedPrice": $xxx.xx, "OfferingType": "Partial Upfront", "RecurringCharges": [ { "RecurringChargeAmount": $xx.xx, "RecurringChargeFrequency": "Hourly" } ] } ] } ``` You can also pass the following parameters to limit the scope of what is returned: + `--reserved-nodes-offering-id` – The ID of the offering that you want to purchase. + `--node-type` – The node type filter value. Use this parameter to show only those reservations matching the specified node type. + `--duration` – The duration filter value, specified in years or seconds. Use this parameter to show only reservations for this duration. + `--offering-type` – Use this parameter to show only the available offerings matching the specified offering type. After you have information about the available reserved node offerings, you can use the information to purchase an offering. The following `purchase-reserved-nodes-offering` example purchases new reserved nodes For Linux, macOS, or Unix: ``` aws memorydb purchase-reserved-nodes-offering \ --reserved-nodes-offering-id 0193cc9d-7037-4d49-b332-d5e984f1d8ca \ --reservation-id reservation \ --node-count 2 ``` For Windows: ``` aws memorydb purchase-reserved-nodes-offering ^ --reserved-nodes-offering-id 0193cc9d-7037-4d49-b332-d5e984f1d8ca ^ --reservation-id MyReservation ``` + `--reserved-nodes-offering-id` represents the name of reserved nodes offering to purchase. + `--reservation-id` is a customer-specified identifier to track this reservation. **Note** The Reservation ID is a unique customer-specified identifier to track this reservation. If this parameter is not specified, MemoryDB automatically generates an identifier for the reservation. + `--node-count` is the number of nodes to reserve. It defaults to 1. This produces output similar to the following: ``` { "ReservedNode": { "ReservationId": "reservation", "ReservedNodesOfferingId": "0193cc9d-7037-4d49-b332-xxxxxxxxxxxx", "NodeType": "db.xxx.large", "StartTime": 1671173133.982, "Duration": 94608000, "FixedPrice": $xxx.xx, "NodeCount": 2, "OfferingType": "Partial Upfront", "State": "payment-pending", "RecurringCharges": [ { "RecurringChargeAmount": $xx.xx, "RecurringChargeFrequency": "Hourly" } ], "ARN": "arn:aws:memorydb:us-east-1:xxxxxxxx:reservednode/reservation" } } ``` After you have purchased reserved nodes, you can get information about your reserved nodes. The following `describe-reserved-nodes` example returns information about reserved nodes for this account. ``` aws memorydb describe-reserved-nodes ``` This produces output similar to the following: ``` { "ReservedNodes": [ { "ReservationId": "ri-2022-12-16-00-28-40-600", "ReservedNodesOfferingId": "0193cc9d-7037-4d49-b332-xxxxxxxxxxxx", "NodeType": "db.xxx.large", "StartTime": 1671150737.969, "Duration": 94608000, "FixedPrice": $xxx.xx, "NodeCount": 1, "OfferingType": "Partial Upfront", "State": "active", "RecurringCharges": [ { "RecurringChargeAmount": $xx.xx, "RecurringChargeFrequency": "Hourly" } ], "ARN": "arn:aws:memorydb:us-east-1:xxxxxxxx:reservednode/ri-2022-12-16-00-28-40-600" } ] } ``` You can also pass the following parameters to limit the scope of what is returned: + `--reservation-id` – You can assign your own identifier to the reserved nodes that you purchase to help track them. + `--reserved-nodes-offering-id` – The offering identifier filter value. Use this parameter to show only purchased reservations matching the specified offering identifier. + `--node-type` – The node type filter value. Use this parameter to show only those reservations matching the specified node type. + `--duration` – The duration filter value, specified in years or seconds. Use this parameter to show only reservations for this duration. + `--offering-type` – Use this parameter to show only the available offerings matching the specified offering type. ## MemoryDB API The following examples demonstrate how to use the [MemoryDB Query API](https://docs.aws.amazon.com/memorydb/latest/devguide/programmingguide.queryapi.html) for reserved nodes: **DescribeReservedNodesOfferings** Returns details of reserved-node offerings. ``` https://memorydb.us-west-2.amazonaws.com/ ?Action=DescribeReservedNodesOfferings &ReservedNodesOfferingId=649fd0c8-xxxx-xxxx-xxxx-06xxxx75e95f &"Duration": 94608000, &NodeType="db.r6g.large" &OfferingType="Partial Upfront" &Version=2021-01-01 &SignatureVersion=4 &SignatureMethod=HmacSHA256 &Timestamp=20141201T220302Z &X-Amz-Algorithm &X-Amz-SignedHeaders=Host &X-Amz-Expires=20141201T220302Z &X-Amz-Credential= &X-Amz-Signature= ``` The following parameters limit the scope of what is returned: + `ReservedNodesOfferingId` represents the name of reserved nodes offering to purchase. + `Duration` – The duration filter value, specified in years or seconds. Use this parameter to show only reservations for this duration. + `NodeType` – The node type filter value. Use this parameter to show only those offerings matching the specified node type. + `OfferingType` – Use this parameter to show only the available offerings matching the specified offering type. After you have information about the available reserved node offerings, you can use the information to purchase an offering. **PurchaseReservedNodesOffering** Allows you to purchase a reserved node offering. ``` https://memorydb.us-west-2.amazonaws.com/ ?Action=PurchasedReservedNodesOffering &ReservedNodesOfferingId=649fd0c8-xxxx-xxxx-xxxx-06xxxx75e95f &ReservationID=myreservationID &NodeCount=1 &Version=2021-01-01 &SignatureVersion=4 &SignatureMethod=HmacSHA256 &Timestamp=20141201T220302Z &X-Amz-Algorithm &X-Amz-SignedHeaders=Host &X-Amz-Expires=20141201T220302Z &X-Amz-Credential= &X-Amz-Signature= ``` + `ReservedNodesOfferingId` represents the name of reserved nodes offering to purchase. + `ReservationID` is a customer-specified identifier to track this reservation. **Note** The Reservation ID is a unique customer-specified identifier to track this reservation. If this parameter is not specified, MemoryDB automatically generates an identifier for the reservation. + `NodeCount` is the number of nodes to reserve. It defaults to 1. After you have purchased reserved nodes, you can get information about your reserved nodes. **DescribeReservedNodes** Returns information about reserved nodes for this account. ``` https://memorydb.us-west-2.amazonaws.com/ ?Action=DescribeReservedNodes &ReservedNodesOfferingId=649fd0c8-xxxx-xxxx-xxxx-06xxxx75e95f &ReservationID=myreservationID &NodeType="db.r6g.large" &Duration=94608000 &OfferingType="Partial Upfront" &Version=2021-01-01 &SignatureVersion=4 &SignatureMethod=HmacSHA256 &Timestamp=20141201T220302Z &X-Amz-Algorithm &X-Amz-SignedHeaders=Host &X-Amz-Expires=20141201T220302Z &X-Amz-Credential= &X-Amz-Signature= ``` The following parameters limit the scope of what is returned: + `ReservedNodesOfferingId` represents the name of reserved node. + `ReservationID` – You can assign your own identifier to the reserved nodes that you purchase to help track them. + `NodeType` – The node type filter value. Use this parameter to show only those reservations matching the specified node type. + `Duration` – The duration filter value, specified in years or seconds. Use this parameter to show only reservations for this duration. + `OfferingType` – Use this parameter to show only the available offerings matching the specified offering type. ## Viewing the billing for your reserved nodes You can view the billing for your reserved nodes in the Billing Dashboard in the AWS Management Console. **To view reserved node billing** 1. Sign in to the AWS Management Console and open the MemoryDB console at [https://console.aws.amazon.com/memorydb/](https://console.aws.amazon.com/memorydb/). 1. From the Search button on the top of the console, choose **Billing**. 1. Choose **Bills** from the left hand side of the dashboard. 1. Under **AWS Service Charges**, expand **MemoryDB**. 1. Expand the AWS Region where your reserved nodes are, for example **US East (N. Virginia)**. Your reserved nodes and their hourly charges for the current month are shown under **Amazon MemoryDB CreateCluster Reserved Instances**. ![\[Screen capture of a billing statement showing hourly charges for the current month.\]](http://docs.aws.amazon.com/memorydb/latest/devguide/images/reserved-nodes.png) # Replacing nodes MemoryDB frequently upgrades its fleet with patches and upgrades, usually seamlessly. However, from time to time we need to relaunch your MemoryDB nodes to apply mandatory OS updates to the underlying host. These replacements are required to apply upgrades that strengthen security, reliability, and operational performance. You have the option to manage these replacements yourself at any time before the scheduled node replacement window. When you manage a replacement yourself, your instance receives the OS update when you relaunch the node and your scheduled node replacement is canceled. You might continue to receive alerts indicating that the node replacement is to take place. If you've already manually mitigated the need for the maintenance, you can ignore these alerts. **Note** Replacement nodes automatically generated by MemoryDB may have different IP addresses. You are responsible for reviewing your application configuration to ensure that your nodes are associated with the appropriate IP addresses. The following list identifies actions you can take when MemoryDB schedules one of your nodes for replacement: **MemoryDB node replacement options** + **Do nothing** – If you do nothing, MemoryDB replaces the node as scheduled. If the node is a member of a Multi-AZ cluster, MemoryDB provides improved availability during patching, updates, and other maintenance-related node replacements. Replacement completes while the cluster serves incoming write requests. + **Change your maintenance window** – For scheduled maintenance events, you receive an email or a notification event from MemoryDB. In these cases, if you change your maintenance window before the scheduled replacement time, your node now is replaced at the new time. For more information, see [Modifying a MemoryDB cluster](clusters.modify.md). **Note** The ability to change your replacement window by moving your maintenance window is only available when the MemoryDB notification includes a maintenance window. If the notification does not include a maintenance window, you cannot change your replacement window. For example, let's say it's Thursday, November 9, at 15:00 and the next maintenance window is Friday, November 10, at 17:00. Following are three scenarios with their outcomes: + You change your maintenance window to Fridays at 16:00, after the current date and time and before the next scheduled maintenance window. The node is replaced on Friday, November 10, at 16:00. + You change your maintenance window to Saturday at 16:00, after the current date and time and after the next scheduled maintenance window. The node is replaced on Saturday, November 11, at 16:00. + You change your maintenance window to Wednesday at 16:00, earlier in the week than the current date and time. The node is replaced next Wednesday, November 15, at 16:00. For instructions, see [Managing maintenance](maintenance-window.md).