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    Cloud Backup:Limits

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    Cloud Backup:Limits

    Last Updated:Nov 06, 2025

    This topic describes the limits of the Elastic Compute Service (ECS) disaster recovery (CDR) feature on operating systems, platforms, databases, and applications.

    Operating systems

    The following table describes the operating systems that support ECS disaster recovery (CDR).

    Important

    Only the operating systems listed in the following table are supported. For other operating systems, we recommend that you use the async replication feature.

    Operating system

    Version

    Windows Server

    2008 R2, 2012, 2012 R2, and 2016

    Linux

    Important

    For Linux systems, the /boot partition and the / partition must be on the same disk. If they are not, resize the disk manually before you register the protected instance for CDR.

    • Red Hat Enterprise Linux 7.0~7.9

    • Red Hat Enterprise Linux 6.0~6.10

    • CentOS 7.0 to 7.9

    • CentOS 6.0 to 6.10

      Note

      Only 64-bit CentOS is supported.

    • SUSE Linux Enterprise Server 12.0 to 12.3

      Important

      • Only 64-bit SUSE Linux Enterprise Server is supported.

      • If SUSE Linux Enterprise Server 12.1 runs on a VMware virtual machine (VM), a black screen appears after you restart the VM. The black screen is caused by operating system errors, but not by ECS disaster recovery (CDR).

    • Alibaba Cloud Linux 2.1903 LTS 64-bit

      The following kernel versions of Alibaba Cloud Linux 2.1903 LTS 64-bit are supported:

      • 4.19.91-25.1.al7.x86_64

      • 4.19.91-24.1.al7.x86_64

      • 4.19.91-23.al7.x86_64

      • 4.19.91-22.2.al7.x86_64

    Platforms

    ECS disaster recovery (CDR) is implemented based on the disk-level data replication technology and is independent of the underlying platform. The following table describes the platforms that support ECS disaster recovery (CDR).

    Infrastructure

    Version

    Physical machine

    Full support

    vSphere

    6.7 and later

    Databases and applications

    You can apply the replication technology of ECS disaster recovery (CDR) to all types of databases and applications.

    In most cases, automated scripts are required for various applications to ensure consistency among updates. You can use the tools and scripts that are provided by Alibaba Cloud to implement ECS disaster recovery (CDR). This ensures smooth recovery of applications.

    Other limits

    ECS disaster recovery (CDR) also has the following limits:

    • Disaster recovery is not supported for ECS instances that use the NVMe protocol to communicate with disks.

    • An ECS instance that is protected by disaster recovery must have at least 1.5 GB of available memory reserved for the operating system. Otherwise, the disaster recovery may fail.

    • If the size of a physical volume where the system disk of an ECS instance resides exceeds 2 TB, you cannot perform a full restoration on the ECS instance.

    • A single physical volume of a data disk cannot exceed 32 TB.

    • Disk write limits:

      • Linux

        If the average I/O size is 4 KB, the maximum disk write speed is about 10 MB/s. If the average I/O size is 64 KB, the maximum disk write speed is about 30 MB/s.

      • Windows

        The maximum disk write speed is 10 MB/s.

    • The total throughput supported by a single site pair is 400 Mbit/s.

      If the data volume exceeds this limit, both the RPO and RTO may be prolonged. When you design a disaster recovery solution, you must evaluate the business situation of protected servers and estimate the amount of data written to disks.