If your workload changes—for example, if it is distributed across smaller instances, consolidated onto larger instances, or expanded across zones—you can split, merge, or modify existing reserved instances. This flexibility allows you to match them to pay-as-you-go instances of different types and in different zones, ensuring you continue to receive discounts and can efficiently manage and optimize the cost and usage of your cloud resources.
For clarity, a reserved instance before being split, merged, or modified is called a source reserved instance. After the operation, it is called a destination reserved instance.
Prerequisites
Before you split, merge, or modify a reserved instance, ensure that:
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The reserved instance is in the In Effect state.
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The reserved instance has no ongoing split, merge, or modification requests.
Split a reserved instance
If your workload is distributed across multiple, smaller pay-as-you-go instances, you can split one reserved instance into multiple reserved instances with lower computing power. This allows you to align your reserved instances more closely with your running pay-as-you-go instances, accommodating your workload distribution.
Limitations
The following limitations apply when you split a reserved instance:
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Reserved instances of the gn6i and t5 instance families cannot be split.
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The destination reserved instances must have the same reservation type, payment type, expiration date, region/zone, and instance type prefix as the source reserved instance.
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The total computing power of the destination reserved instances must equal the computing power of the source reserved instance.
NoteThe computing power of a reserved instance = normalization factor of the instance type × quantity. To find the normalization factor for different instance types, see View normalization factors.
Procedure
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On the Reserved Instance page, find the reserved instance that you want to split. In the Actions column, click
> Split. -
In the Split Reserved Instance dialog box, configure the name, instance type, and quantity for each destination reserved instance.
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Click OK. You can then view the operation results.
Merge reserved instances
If your workload is concentrated on a few large instances, you can merge multiple reserved instances into a single one with greater computing power. This lets you more effectively match these large pay-as-you-go instances.
Limitations
The following limitations apply when you merge reserved instances:
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Reserved instances of the gn6i and t5 instance families cannot be merged.
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The source reserved instances you merge must have the same reservation type, payment type, expiration date, region/zone, and instance type prefix.
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The quantity for the destination reserved instance cannot exceed 100.
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The computing power of the destination reserved instance must equal the sum of the computing power of the source reserved instances.
NoteThe computing power of a reserved instance = normalization factor of the instance type × quantity. To find the normalization factor for different instance types, see View normalization factors.
Procedure
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On the Reserved instances page, find one of the reserved instances that you want to merge. In the Actions column, click
> Merge. -
In the Merge Reserved Instances dialog box, select the source reserved instances, and then configure the name, instance type, and quantity for the destination reserved instance.
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Click OK. You can then view the operation results.
Modify the zone of a reserved instance
If a reserved instance's current zone is no longer suitable due to business expansion or migration, you can modify its zone to better match your pay-as-you-go instances.
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On the Reserved instances page, find the reserved instance that you want to modify and click Modify in the Actions column.
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In the Modify Reserved Instance dialog box, configure the Name and Region / zone.
You can change the Region / zone only within the same region. The following modifications are supported:
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For a zonal reserved instance:
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You can change it to another zone within the same region.
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You can change its scope from a specific zone to the entire region, making it a regional reserved instance.
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For a regional reserved instance: You can change its scope from regional to a specific zone, making it a zonal reserved instance.
NoteIf the destination zone has insufficient inventory for the corresponding instance type, you cannot select that zone.
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Click OK. You can then view the operation results.
Operation results
After you submit a request, the source reserved instance enters the Updating state, and the destination reserved instance enters the Creating state.
You cannot cancel an in-progress request. To roll back a change, you must perform the reverse operation. For example, to undo a split, you can merge the resulting reserved instances.
After the request is processed:
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If the operation is successful:
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Source reserved instance
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Enters the inactive state. Deactivation is effective at the start of the hour the operation completes, and its price is set to 0 CNY.
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You can view only historical bills for the source reserved instance.
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Destination reserved instance
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Enters the In Effect state. Activation is effective at the start of the hour the operation completes.
For example, if you split a zonal reserved instance with a capacity reservation for the ecs.g6.2xlarge instance type into two zonal reserved instances with capacity reservations for the ecs.g6.xlarge instance type at 20:30 on May 28, 2024, the source reserved instance becomes inactive at 20:00 on May 28, 2024, and the destination reserved instances become active at 20:00 on May 28, 2024.
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For a zonal reserved instance, the system also automatically updates the associated capacity reservation.
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If the destination reserved instance successfully matches a pay-as-you-go instance, the system applies the discount to your bill within the same hour.
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If the operation fails, the source reserved instance remains active and its functionality is unaffected.