Suggestions on Instance Selection

Overview

Before buying a GeminiDB Cassandra instance, you need to consider factors such as price, performance, workloads, and scenarios. GeminiDB Cassandra instances have different storage specifications and billing modes. This section describes these differences to help you quickly select a suitable instance.

Billing Mode

There are two billing modes: yearly/monthly and pay-per-use.

Billing Mode	Yearly/Monthly	Pay-per-use
Payment	Prepaid Settled based on the required duration in your order.	Postpaid Settled based on how long you have actually used your instance.
Billing Cycle	Billed based on the required duration in your order.	Pricing is listed on a per-hour basis, and bills are calculated down to the second.
Billing Items	Instance specifications (vCPUs and memory), storage, backup storage, and EIP	Instance specifications (vCPUs and memory), storage, backup storage, and EIP
Changing the Billing Mode	A yearly/monthly instance can be changed to pay-per-use. The change is applied only after the yearly/monthly instance expires. For details, see Changing a Yearly/Monthly Instance to Pay-per-Use.	A pay-per-use instance can be changed to yearly/monthly. For details, see Changing a Pay-per-Use Instance to Yearly/Monthly.
Changing Specifications	Supported	Supported
Scenario	If your future usage is predictable, this billing mode is generally less expensive than pay-per-use. It is recommended for long-term users.	This billing mode is ideal for dynamic compute workloads. You can enable or delete your instance at any time.

The following table lists the billing items.

**Table 1** Billing items
Billing Item	Description	Formula
Instance specifications	You are billed for vCPUs and memory. Compute and storage capabilities vary depending on instance specifications.	Unit price × Required duration See the estimated price of a cluster instance in GeminiDB Price Calculator.
Storage	You are billed for storage based on unified standards.	Unit price × Storage × Required duration See the estimated price of an instance with specified storage in GeminiDB Price Calculator.
EIP	An EIP is required if an instance needs to access the Internet. You are billed for bandwidth, traffic, and IP address reservation. EIP for a yearly/monthly instance: billed by bandwidth EIP for a pay-per-use instance: billed by bandwidth, traffic, or shared bandwidth. You are also billed for IP reservation.	Tiered pricing based on fixed bandwidth 0 Mbit/s to 5 Mbit/s (included): billed at a fixed unit price per Mbit/s Greater than 5 Mbit/s: billed at a different price per Mbit/s For details about the unit price, see ECS Price Calculator or EIP Price Calculator.

The following table lists the billing items.

**Table 2** Billing items
Billing Item	Description	Formula
Instance specifications	You are billed for vCPUs and memory. Compute and storage capabilities vary depending on instance specifications.	Unit price × Required duration See the estimated price of a cluster instance in GeminiDB Price Calculator.
Storage	You are billed for storage based on unified standards.	Unit price × Storage × Required duration See the estimated price of an instance with specified storage in GeminiDB Price Calculator.
Backup storage	You are billed for backup storage based on unified standards.	Unit price x Billed backup storage × Required duration See the estimated price of an instance with specified backup storage in GeminiDB Price Calculator. NOTE: The billing duration indicates the period during which your storage exceeded the free quota.
EIP	An EIP is required if an instance needs to access the Internet. You are billed for bandwidth, traffic, and IP address reservation. EIP for a yearly/monthly instance: billed by bandwidth EIP for a pay-per-use instance: billed by bandwidth, traffic, or shared bandwidth. You are also billed for IP reservation.	Yearly/Monthly and pay-per-use You can purchase a bandwidth add-on package or a shared traffic package. Tiered pricing based on fixed bandwidth 0 Mbit/s to 5 Mbit/s (included): billed at a fixed unit price per Mbit/s Greater than 5 Mbit/s: billed at a different price per Mbit/s For details, see the estimated EIP bandwidth unit price in ECS Price Calculator or EIP Price Calculator.

Functions Supported by Different Instance Types

Function Set	Function	Classic Storage	Cloud Native Storage
Specifications change	Changing vCPUs and Memory	√	√
	Manually Adding Nodes	√	√
	Automatically Adding Nodes	√	√
	Manually Deleting Nodes	√	√
	Manually Scaling Up Storage Space	√	√
	Automatically Scaling Up Storage Space	√	√
	Manually Scaling Down Storage Space	√	√
	Upgrading the Kernel Minor Version	√	√
Intra-region DR	Intra-region DR	√	√
Cross-region active-active DR	Cross-region Dual-active DR	√	√
Data backup	Managing Automated Backups	√	√
	Managing Manual Backups	√	√
	Managing Cross-Region Backups	√	√
	Managing Table-level Backups	√	√
Data restoration	Rebuilding an Instance	√	√
	Restoring a Backup to a New Instance	√	√
	Restoring a Backup to a Specified Point in Time	√	√
	Restoring Databases or Tables to a Specified Time Point	√	√