How to configure parameters when purchasing an Alibaba Cloud ES instance - Elasticsearch

This topic describes the features of each type of node for an Alibaba Cloud Elasticsearch cluster and provides instructions on how to configure node-related parameters when you purchase an Alibaba Cloud Elasticsearch cluster.

Data node

Data nodes are used to store indexes. You can use data nodes to add, remove, modify, search for, or aggregate documents in indexes. Data nodes have high CPU, memory, and I/O requirements. When you optimize the performance of a cluster, you must monitor the statuses of the data nodes in the cluster. If the resources of the cluster are insufficient, we recommend that you add data nodes to the cluster.

Note

If dedicated master nodes are purchased, data nodes are used only as data nodes.
If dedicated master nodes are not purchased, data nodes are also used as dedicated master nodes.
After you scale in an Elasticsearch cluster, the cluster will not be restarted if it is deployed in the new architecture (V3) but will be restarted if it is deployed in the old architecture (V2). If the load of the cluster is not high and indexes in the cluster have replica shards, the cluster can still provide services during the restart. However, access timeouts may occur during a cluster restart in some scenarios, such as scenarios in which large amounts of data are written or queried. Therefore, we recommend that you restart a cluster during off-peak hours.

Parameter	Description
Data Node Type	We recommend that you use data nodes with 2 vCPUs and 4 GiB of memory in testing environments and use data nodes with higher specifications in production environments.
Data Node Disk Type	ESSD (default): This type of disk features low latency, quick response, and high data throughput and is suitable for latency-sensitive applications or I/O intensive business scenarios. For more information about the specifications of ESSDs, see Node specifications. For more information about the performance of ESSDs, see ESSDs. Ultra Disk: This type of disk is cost-effective and suitable for logging and analyzing large volumes of data. Standard SSD: This type of disk is suitable for online data analytics and searches that require high IOPS and quick responses. Note You can view the supported disk types on the buy page. After a cluster is created, you cannot change the disk types of nodes in the cluster.
Data Node Storage Performance Level (PL)	If you set the Data Node Disk Type parameter to ESSD, you need to configure this parameter.
Data Node Disk Encryption	Disk encryption offers the maximum data security without requiring you to make additional changes to your businesses and applications. However, disk encryption may have a small impact on the performance of your cluster. Disk encryption is free of charge. No additional fees are generated when you read data from or write data to encrypted disks. Note You cannot disable disk encryption for encrypted disks. You cannot enable disk encryption for purchased disks. When you upgrade the configuration of a cluster, you cannot enable disk encryption for purchased disks. If you purchase cloud disks when you upgrade the configuration of the cluster, you can enable disk encryption.
Data Node Storage Space	The storage space of each data node depends on the disk type. Unit: GiB. Enterprise SSD (ESSD): Provides up to 6 TiB of storage space. Ultra Disk: For a cluster of V6.7, V7.7, or a version later than V7.7, the maximum value of this parameter is 20480. For a cluster of another version, the maximum value of this parameter is 5120. Standard SSD: For a cluster of V6.7, V7.7, or a version later than V7.7, the maximum value of this parameter is 6144. For a cluster of another version, the maximum value of this parameter is 2048. Note When you resize an ultra disk with a storage space greater than 2,560 GiB, only a blue-green update can be performed for the ultra disk because the disk is designed to run in disk arrays or RAID 0.
Data Nodes	The number of nodes that you purchase must be a multiple of the number of zones. Important A cluster that contains only two data nodes has high split-brain risks and delivers low stability. If a cluster of an earlier version, such as V6.X or V5.X, contains only two data nodes, a dedicated master node may not be selected if node restart is required, and the cluster may not provide services. Therefore, you must configure this parameter as needed.

Kibana node

This setting is enabled by default and cannot be changed.
A Kibana node with 1 vCPU and 2 GiB of memory is free of charge. However, we recommend that you use the Kibana node with 1 vCPU and 2 GiB of memory only for testing purposes.
Due to the impact on cluster performance and stability, we recommend that you purchase a Kibana node with 2 vCPUs and 4 GiB of memory or higher specifications.

Dedicated master node

You can use dedicated master nodes to perform operations on clusters, such as creating indexes, deleting indexes, tracking nodes, and allocating shards. The stability of dedicated master nodes is important to the health of clusters. By default, each node in a cluster may be used as a dedicated master node. Operations, such as data indexing, searches, and queries, require many CPU, memory, and I/O resources. To ensure the stability of a cluster, we recommend that you purchase dedicated master nodes to separate the dedicated master nodes from data nodes.

Important

If the dedicated master nodes in your cluster are free of charge, you are charged for these nodes after you upgrade the configuration of the cluster.
If you perform a blue-green change for a cluster that does not contain dedicated master nodes and is deployed in the old architecture (V2), data nodes will be restarted the next time you perform a change on the cluster. Therefore, we recommend that you purchase dedicated master nodes.

Parameter	Description
Dedicated Master Node	To improve the stability of your services, we recommend that you purchase dedicated master nodes. For a multi-zone Elasticsearch cluster, the default value of this parameter is Yes, and you cannot change the value. Note You cannot release the dedicated master nodes that you have purchased. After a cluster is created, you can purchase dedicated master nodes when you upgrade the configuration of the cluster.
Dedicated Master Node Type	You can view the supported specifications on the buy page.
Dedicated Master Node Disk Type	ESSD (default): This type of disk features low latency, quick response, and high data throughput and is suitable for latency-sensitive applications or I/O intensive business scenarios. For more information about the specifications of ESSDs, see Node specifications. For more information about the performance of ESSDs, see ESSDs. Ultra Disk: This type of disk is cost-effective and suitable for logging and analyzing large volumes of data. Standard SSD: This type of disk is suitable for online data analytics and searches that require high IOPS and quick responses. You can view the supported disk types on the buy page.
Dedicated Master Node Storage Space	The value of this parameter can be only 20G.
Dedicated Master Nodes	The value of this parameter can be only 3.

Cold Data Nodes

If your business involves both of the following index types, we recommend that you purchase warm nodes to implement the hot-warm architecture. This architecture improves the processing performance and service stability of a cluster.

Frequently queried or written indexes
Infrequently queried or written indexes, typically indexes of records

For more information, see "Hot-Warm" Architecture in Elasticsearch 5.x.

Note

If an instance has dedicated master nodes, cold data nodes function only as data nodes.

If dedicated master nodes are not purchased, warm nodes are also used as dedicated master nodes.

Parameter	Description
Cold data node	Purchased cold data nodes cannot currently be canceled.
Cold data node specifications	For supported specifications, see the buy page. For scenarios with high I/O requirements and large storage demands, you can also use cost-effective local disk instance types. The specification is `20 vCPUs and 88 GiB of memory (SATA: 8 × 7,300 GiB)`. The following limits apply to local disk instance types: Only kernel-enhanced instances of V7.17 that are deployed based on the new Cloud-native Control Architecture (V3) and have two or three zones support local disk instance types. For V3 architecture instances, blue-green deployment is not supported for node-level changes, such as node scale-out, on local disk instance types. Note To prevent data loss on local storage, use at least one replica when you select a local disk instance type. You cannot change a local disk instance type to a cloud disk-based instance type. If your application architecture cannot ensure data reliability, create an instance with a cloud disk-based specification. Machine-level snapshots are not supported for cloud disk-based types.
Cold Node Storage Class	Support is currently limited to ultra disks.
Cold Data Node Disk Encryption	Disk encryption offers the maximum data security without requiring you to make additional changes to your businesses and applications. However, disk encryption may have a small impact on the performance of your cluster. Disk encryption is free of charge. No additional fees are generated when you read data from or write data to encrypted disks. Note You cannot disable disk encryption for encrypted disks. You cannot enable disk encryption for purchased disks. When you upgrade the configuration of a cluster, you cannot enable disk encryption for purchased disks. If you purchase cloud disks when you upgrade the configuration of the cluster, you can enable disk encryption.
Cold Data Node Storage	The minimum value of this parameter is 500. Unit: GiB.
Number of Cold Data Nodes	The number of nodes that you purchase must be a multiple of the number of zones.

After you purchase cold data nodes, the system adds -Enode.attr.box_type to the node startup parameters, as shown in the following table.

Node type	Startup parameter
Data node	-Enode.attr.box_type=hot
Cold data node	-Enode.attr.box_type=warm

Client node

You can purchase client nodes to share the CPU overheads of data nodes. This improves the processing performance and service stability of a cluster. For CPU-intensive services, such as services that require many aggregate queries, we recommend that you purchase client nodes.

Parameter	Description
Client Node	You cannot release the client nodes that you have purchased for a cluster that is deployed in the cloud-native control architecture (a cluster of V7.16 or later). You can check whether you can release the client nodes in your cluster on the buy page.
Coordinator node specifications	You can view the supported specifications on the buy page.
Client Node Disk Type	Support is currently limited to ultra disks.
Client Node Storage Space	The value of this parameter can be only 20G.
Client Nodes	The number of nodes that you purchase must be a multiple of the number of zones.

References

For more information about how to purchase an Elasticsearch cluster, see Create an Alibaba Cloud Elasticsearch cluster.
For more information about the nodes, see Node | Elasticsearch Guide.
For more information about the pricing of node specifications, see Pricing.