This topic describes the limits when you use .

Database backup

  • On-premises database servers must be connected to virtual private clouds (VPCs) by using VPNs or Express Connect circuits. Make sure that you can use an HBR client to access an IP address in the following CIDR blocks of VPCs from an on-premises server:,, and
  • HBR supports a limited number of database versions, operating systems, and backup features. For more information, see Database backup.

Back up files

  • Backup clients for Windows support Volume Shadow Copy Service (VSS). You can create only one VSS snapshot at a time. If you use VSS to back up data, you cannot back up files from multiple paths or Universal Naming Convention (UNC) paths. You cannot use wildcard characters or exclude files.
  • If HBR attempts to back up a file on which HBR has read permissions but the file is being modified by other applications, an incomplete backup occurs. You must ensure the integrity of backup data at the application layer.
  • If HBR attempts to back up a file on which HBR does not have read permissions or the file is locked by other processes, an incomplete backup occurs. The status of the backup job is displayed as partially completed when the job ends.

VMware VM backup

  • You must install a vSphere Web Client of 5.5, 6.0, 6.5, or 6.7 on each virtual machine for which you want to create a backup file.
  • A vCenter Server and an ESXi hypervisor must allow access from a backup gateway by using a fully qualified domain name (FQDN) or an IP address.
  • If you want to back up a virtual machine (VM), make sure that no snapshots are created for the VM. Otherwise, the following message appears when you select the VM: You cannot back up the virtual machine because you have already created a snapshot. If a snapshot exists, you must delete the snapshot before you can back up the VM.
  • You cannot back up VMs that have SCSI devices because vSphere VMs do not support shared SCSI devices.
  • The name of a VM that you want to back up cannot contain the following characters.

    ` ^ ~ = ; ! / ( ) [ ] { } @ $ \ & # % +

  • If you use Changed Block Tracking (CBT) to perform an incremental backup for a VM, the backup attempt fails in the following scenarios:
    • The hardware version of the VM is earlier than version 7.
    • CBT is disabled on the VM.
    • The disk of the VM uses raw device mapping (RDM) in physical compatibility mode.
    • The disk mode of the VM is independent_persistent or independent_nonpersistent.

SAP HANA backup

You can install only one SAP HANA instance on an ECS instance. Otherwise, the following error message appears: Failed to install SAP HANA.

Apsara File Storage NAS backup

NAS backup does not support access control lists (ACLs) for Apsara File Storage NAS Server Message Block (SMB) file systems. For more information, see Features.

OSS backup

  • HBR cannot back up or restore symbolic links, object ACLs, or objects in archive buckets.
  • To improve the performance of incremental backup, HBR uses the latest OSS inventory list within the previous 7 days to back up data.
    The system may require a short period of time to generate an OSS inventory list. When you use the OSS inventory list, take note of the following limits:
    • If no inventory list is detected by a running backup job, the backup job fails.
    • If a backup job detects that the OSS inventory list remains the same as the OSS inventory list of the previous backup, the backup job fails.
    • If a backup job is triggered, HBR uses only the latest OSS inventory list to back up data. After a backup job is completed, the objects that you add to the OSS inventory list are backed up in the next backup cycle.
    • The interval at which backup jobs are performed must be greater than or equal to the interval at which OSS inventory lists are generated. This way, you can use an OSS inventory list each time you run a backup job.

ECS disaster recovery

This section describes the limits on Elastic Compute Service (ECS) disaster recovery, including the limits on operating systems, architectures, databases, and applications. For more information, see Limits on ECS disaster recovery.

VMware disaster recovery

The VM that you want to restore is not a Linux VM whose system disk is created on a logical volume managed by Logical Volume Manager (LVM).

VMware VM migration

The following table describes the limits on VMware VMs.

Item Description
Region The number of regions that are supported by HBR to use this feature increases over time. You can log on to the HBR console to view the supported regions.
Operating system CentOS, Ubuntu, CoreOS, SUSE, OpenSUSE, Red Hat, Windows Server 2008 R2, Windows Server 2012, and Windows Server 2016.
GRUB version Before you can migrate a VMware VM, GRUB of the required version must be installed on the VM based on the operating system of the VM.
  • If the VM runs Linux, you must upgrade your GRUB to GRUB V1.99 or a later version.
  • If the VM runs Linux of an earlier version, such as CentOS 5, Red Hat 5, or Debian 7, you must upgrade your GRUB to GRUB V1.99 or a later version.
vCenter version vCenter Server 5.5, 6.0, 6.5, 6.7, and 7.0. A VCenter client and ESXi hypervisor must allow access from a backup gateway by using an FQDN or an IP address.