Notes and Constraints

Number of backups

Unlimited

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Backup capacity (GB)

Unlimited

You are advised not to back up a server whose disk size exceeds 4 TB.

Vault name

A name must contain 1 to 64 characters including digits, letters, underscores (_), or hyphens (-).

Backup name

A name must contain 1 to 64 characters including digits, letters, underscores (_), or hyphens (-).

Tag key

• Can contain 1 to 36 Unicode characters.
• Cannot be left blank, cannot start or end with spaces or contain non-printable ASCII (0-31) characters or any of the following special characters: =*<>\,|/

Tag value

• Can contain 0 to 43 Unicode characters.
• Can be an empty string, but cannot start or end with spaces or contain non-printable ASCII (0-31) characters or the following special characters: =*<>\,|/

Restoring data

• Only backups in the Available or Locked vaults can be used to restore data.
• Concurrent data restoration is not supported.
• An SFS Turbo file system backup cannot be used to restore data to the original file system.
• Restoring from a cloud server backup:
  1. When restoring from a cloud server backup, backup of a data disk cannot be restored to the system disk.
  2. Data cannot be restored to servers in the Faulty state.

• Restoring from a cloud disk backup:
  1. Backup and restoration of local disks are not supported.
  2. You can back up specific disks on a server, but such a backup must be restored as a whole. File- or directory-level restoration is not supported.
  3. If the server OS is changed after the system disk is backed up, the system disk backup cannot be restored to the original system disk due to reasons such as disk UUID change. You can use the system disk backup to create a new disk and copy data to the original system disk.
  4. Backups can only be restored to original disks. If you want to restore a backup to a different disk, use the backup to create a new disk.
• Restoring from a file backup:
  1. The Agent on the server must be Normal.
  2. You are advised not to restore file backups when applications are running. Stop the applications and then restore files.
• Restoring to cloud servers using VMware backups:
  1. Backups synchronized to the cloud cannot be used to create cloud servers.
  2. Synchronized backups can only be used to restore to other cloud servers and can be restored to system disks or data disks.
  3. Before the restoration, configure security groups according to the procedure. Otherwise, the restoration may fail.
  4. When LVM is used to manage the system disks of VMware VMs, VMware backups cannot be restored to cloud servers.
  5. VMware backup data only can be restored to cloud servers running the same OS as the source VMware VMs, for example, Linux to Linux, Windows to Windows.
  6. When recovering data on the cloud from a Windows VMware backup, the system disk's boot partition number of the backup must be 2.

Creating a backup policy

• A maximum of 32 backup policies can be created in each account. A vault can be associated with only one backup policy.
• Backup policies can be applied to the following types of vaults: server backup vaults, disk backup vaults, SFS Turbo backup vaults.
• A backup policy must be enabled before it can be used for periodic backups.
• When a backup time and a replication time are both configured, ensure that replication starts after backup is complete. Or, replication may fail.
• When expired backups are deleted, automatic backups will be deleted, but manual backups will not.
• CBR by default performs a full backup for a resource in the initial backup and incremental backups in all subsequent backups.

Creating a replication policy

• A maximum of 32 replication policies can be created in each account. A vault can be associated with only one replication policy.
• You can only apply replication policies to server backup vaults, SFS Turbo backup vaults, and hybrid cloud backup vaults.

Associating resources

A vault can be associated with a maximum of 256 resources.

Creating a backup

• Only servers in the Running or Stopped state can be backed up.
• Only disks in the Available or In-use state can be backed up.
• Only file systems in the Available state can be backed up.
• Only desktops in the Available or In-use state can be backed up.
• Frozen disks and servers in the retention period cannot be backed up.
• If a backup of a resource is in progress, other policy or manual backups of this resource will not be performed.
• Backups cannot be downloaded to a local PC or uploaded to OBS.
• A vault and its associated servers or disks must be in the same region.
• The minimum interval between two full backups is 1 day.

Deleting a backup

• Only backups in the Available or Error state can be deleted.
• Backups in a Deleting vault cannot be deleted.

File backup

• Before backing up a file, ensure that the file is not being changed by an application, and the backup client has the read permissions on this file. Otherwise, the backed-up data will be incomplete.
• Before backing up a file, ensure that the file is not being used by a process, and the backup client has the read permissions on this file. Otherwise, the backed-up data will be incomplete.
• One backup client can have a maximum of 8 files and directories added.
• Each server can only have one Agent installed.
• The number of servers where the Agent can be installed is not limited.
• A single directory can contain a maximum of 500,000 files, and you are advised to reserve at least 4 GB of memory on each backup client to perform file backups.
• A backup client can have a maximum of 100 directories added.
• A path must be an absolute path, for example, a path starting with /, C:\, or D:\. One path can contain a maximum of 200 characters.
• The maximum bandwidth allowed for file backup data transmission is 16 Gbit/s. If the maximum bandwidth is reached, flow control will be triggered.
• File backup cannot back up the files stored in SFS file systems that are mounted to cloud servers.
• Backup may fail on directories with frequent file writes in Windows.
• At least 50 Mbit/s network bandwidth is required in cross-cloud or cross-region file backup scenarios.

Application-consistent backup

• Application-consistent backup is currently not supported for cluster applications, such as, MySQL Cluster. It is supported only for applications on standalone servers.
• You are advised to perform application-consistent backup in off-peak hours.

VMware backup

• VM backups from the following VMware vSphere versions can be synchronized to the cloud: 5.1, 5.5, 6.0, 6.5, 6.7.
• Currently, only VMware ESXi VMs can be backed up to the cloud.
• To achieve better performance and operation experience, only the OSs that have passed the compatibility test allow for cloud recovery. If you only need to restore data to on-premises VMware VMs, there is no restriction on the OS version. For details about the supported OSs, see hybrid cloud backup constraints.
• The VDDK version of VMware 6.7 or earlier VMs must be 6.0.3.
• Backups synchronized to the cloud can only be restored to existing cloud servers running the same type of OS. Recovery of partial disks on a VM is not supported.
• Servers whose system disks are configured with LVM cannot be restored on cloud.
• The backup bandwidth should be at least 100 Mbit/s. The sizes of disks on the VMware VMs to be backed up to the cloud should be integers in GB.

• A VMware VM can be associated with only one vault. Multiple VMware VMs can use the same vault.

Migrating a resource

• Resources can be migrated only when the source and destination vaults are in the Available or Locked state.
• The source and destination vaults for resource migration must be of the same types. For example, resources in a server backup vault can be migrated to another server backup vault, but cannot be migrated to another disk backup vault.
• The remaining capacity of the destination vault must be greater than the size of resource backups to be migrated.
• Cross-account resource migration is currently not supported.
• The source and destination vaults must be in the same region.

Auto capacity expansion

• Auto capacity expansion does not take effect if it is enabled after the vault is full.

Replicating a backup

• Cloud disk backups cannot be replicated to other regions.
• Only server backups in the Available or Locked vaults can be replicated.
• Only replication-supported regions can be selected as destination regions.
• Only backups can be replicated. Backup replicas cannot be replicated again but can be used to create images or SFS Turbo file systems.
• A backup vault can be replicated to different destination regions. For manual and policy-based vault replication, a vault can only be replicated to a destination region once. It cannot be replicated to that region again, even if its backups have been deleted. Manual replication: A backup can be manually replicated to the destination region as long as it has no replica in that region. A backup can be manually replicated again if its replica in the destination region has been deleted.

For more information, see Replicating a Backup Across Regions.

Backup locking

• Backup locking cannot be disabled after it is enabled.
• After backup locking is enabled, associated resources cannot be dissociated and files cannot be migrated. However, file backup clients that do not have backups can be dissociated from vaults.
• Backup locking does not affect normal backup, restoration, and replication operations.
• After backup locking is enabled, policy-based backups can only be deleted after they expire.
• Manual backups are not affected by backup locking and can be manually deleted.
• After backup locking is enabled, pay-per-use vaults cannot be deleted if they contain backups, but yearly/monthly vaults can be unsubscribed from.
• Backup locking is not supported for VMware backup.