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    Cloud Backup:Limits

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    Cloud Backup:Limits

    Last Updated:Apr 08, 2026

    ECS disaster recovery (CDR) has specific requirements and limits on operating systems, platforms, databases, and applications. Review the following information before setting up disaster recovery.

    Operating systems

    ECS disaster recovery (CDR) supports only the following operating systems.

    Important

    Only the operating systems listed in the following table are supported. For unsupported operating systems, use the async replication feature instead.

    Operating system

    Version

    Windows Server

    2008 R2, 2012, 2012 R2, and 2016

    Linux
    Important

    For Linux systems, the /boot partition and the / partition must reside on the same disk. If they do not, resize the disk manually before registering the protected instance for CDR.

    • Red Hat Enterprise Linux 7.0 to 7.9

    • Red Hat Enterprise Linux 6.0 to 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.

      • SUSE Linux Enterprise Server 12.1 running on a VMware virtual machine (VM) may display a black screen after a restart. This issue is caused by operating system errors, 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) uses disk-level data replication technology and is independent of the underlying platform. The following table lists the tested and verified platforms.

    Infrastructure

    Version

    Physical machine

    Full support

    vSphere

    6.7 and later

    Databases and applications

    The replication technology of ECS disaster recovery (CDR) is application-agnostic and supports all types of databases and applications.

    Most applications require automated scripts to maintain update consistency. Alibaba Cloud provides tools and scripts to work with ECS disaster recovery (CDR) and help applications recover smoothly.

    Other limits

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

    • ECS instances that use the NVMe protocol to communicate with disks do not support disaster recovery.

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

    • Full restoration is not supported for an ECS instance whose system disk resides on a physical volume larger than 2 TB.

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

    • Disk write limits:

      • Linux

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

      • Windows

        The maximum disk write speed is 10 MB/s.

    • The maximum total throughput for a single site pair is 400 Mbit/s.

      Exceeding this limit may prolong both the Recovery Point Objective (RPO) and Recovery Time Objective (RTO). When designing a disaster recovery solution, evaluate the workload of protected servers and estimate the disk write throughput.