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    Cloud Backup:Limits

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    Cloud Backup:Limits

    Last Updated:Apr 17, 2026

    EBS async replication for Cloud Backup has limits on supported regions, specifications, networks, quotas, and consistency guarantees.

    Supported regions and zones

    The async replication feature is available in the following regions and zones. Additional regions may be added over time. For the latest availability, check the region options when you create a site pair.

    • China (Hangzhou): Zone B, Zone F, Zone G, Zone H, Zone I, Zone J, and Zone K

    • China (Shanghai): Zone B, Zone E, Zone F, Zone G, Zone K, Zone L, Zone M, and Zone N

    • China (Qingdao): Zone B and Zone C

    • China (Beijing): Zone D, Zone F, Zone G, Zone H, Zone I, Zone J, Zone K, and Zone L

    • China (Zhangjiakou): Zone A, Zone B, and Zone C

    • China (Hohhot): Zone A and Zone B

    • China (Ulanqab): Zone A, Zone B, and Zone C

    • China (Shenzhen): Zone C, Zone D, Zone E, and Zone F

    • China (Heyuan): Zone A and Zone B

    • China (Guangzhou): Zone A and Zone B

    • China (Chengdu): Zone A and Zone B

    • China (Hong Kong): Zone B, Zone C, and Zone D

    • Singapore: Zone A, Zone B, and Zone C

    • Japan (Tokyo): Zone A, Zone B, and Zone C

    • South Korea (Seoul): Zone A

    • Philippines (Manila): Zone A

    • Thailand (Bangkok): Zone A and Zone B

    • Malaysia (Kuala Lumpur): Zone A, Zone B, and Zone C

    • Indonesia (Jakarta): Zone A, Zone B, and Zone C

    • Germany (Frankfurt): Zone A, Zone B, and Zone C

    • UK (London): Zone A and Zone B

    • US (Silicon Valley): Zone A and Zone B

    • US (Virginia): Zone A and Zone B

    • UAE (Dubai): Zone A and Zone B

    • SAU (Riyadh - Partner Region): Zone A and Zone B

    Specification and disk limits

    The following table describes the specification limits for async replication and replication pair-consistent groups.

    Item

    Limit

    Replication pairs per disk

    1

    Replication pairs per replication pair-consistent group

    17

    Replication cycle

    15 minutes (data is asynchronously replicated from a primary disk to a secondary disk every 15 minutes)

    Replication rate

    Up to 100 MB/s. May vary based on system load.

    Primary disk category

    ESSDs or ESSD AutoPL disks

    Secondary disk category

    Must be the same disk category, performance level, and capacity as the corresponding primary disk

    The following table describes the disk operation limits for async replication and replication pair-consistent groups.

    Note

    The numbers in the following table correspond to the following limits:

    • After a replication pair is activated, the secondary disk enters the read-only state and no users have write permissions on the disk.

    • Due to the recovery point objective (RPO), the data of a snapshot created for a primary disk may be inconsistent with that of a snapshot created at the same time for the associated secondary disk.

    • Replication is restricted to encrypted disks. Cross-replication between encrypted disks and unencrypted disks is not supported.

    Operation

    Primary disk

    Secondary disk

    Read and write

    Supported

    Not supported (see note 1)

    Disk deletion

    Not supported

    Not supported

    Disk initialization

    Not supported

    Not supported

    Disk resizing

    Not supported

    Not supported

    Disk attaching

    Supported

    Not supported

    Snapshot creation

    Supported

    Supported (see note 2)

    Rollback based on snapshots

    Supported

    Not supported

    Disk category change

    Not supported

    Not supported

    Performance level change

    Not supported

    Not supported

    Disk encryption

    Supported

    Supported (see note 3)

    Multi-attach

    Not supported

    Not supported

    Disk migration with instances

    Not supported

    Not supported

    Network limits

    The following limits apply to ECS networks used for async replication:

    • Single NIC limits:

      After a failover, some operating systems at the disaster recovery site cannot automatically configure the NIC. Manually check and configure the NIC at the disaster recovery site to ensure that the network functions correctly. For more information, see Configure a secondary ENI.

    • Multiple NIC limits:

      • After you attach a secondary ENI to an ECS instance, some images cannot automatically identify the IP address of the secondary ENI or add a route. As a result, the secondary ENI may not function correctly.

      • If you configure a secondary ENI for an ECS instance, verify the IP address of the secondary ENI after a failover to ensure that the secondary ENI functions as expected. For more information, see Configure a secondary ENI.

    • Site pairs do not support ENIs or ECS instances outside a VPC.

    Quota limits

    • Each account supports a maximum of 1,000 disaster recovery site pairs.

    • Each disaster recovery site pair supports a maximum of 512 protection groups.

    • Each protection group supports a maximum disk capacity of 32 TB and a maximum of 17 disks.

    Consistency limits

    EBS async replication supports only crash consistency. Application consistency is not supported. For applications and databases that require strong consistency, configure direct data writes to disks as described in the relevant application or database documentation. Direct writes ensure data consistency and reduce the risk of extended recovery times caused by asynchronous data writes during a disaster.