The cache feature is enabled by default on a backup client for on-premises files to accelerate the data backup process. The cache is used only to accelerate the data backup process, and cannot restore data on an on-premises or remote host.


A Hybrid Backup Recovery (HBR) client is installed for on-premises files. The version of the client is 1.5.0 or later. For more information, see Preparations.

Background information

The cache feature allows you to accelerate the data backup process by caching data entry IDs and metadata. This feature reduces network requests during data backup. You can disable this feature or optimize its settings on the backup source.


You can perform the following steps to create a cache configuration file. You can also disable the cache feature or optimize its settings by using the configuration file. This file is optional. If you do not create a file, the default settings of the feature are used.

  1. Log on to the on-premises server or virtual machine (VM) whose files you want to back up.
  2. Open the installation folder of the backup client.
    You can find the installation path based on the following default installation paths.
    • For backup clients of an earlier version

      Linux: /opt/alibabacloud/hbr

      Windows: C:\Program Files\Aliyun Hybrid Backup Service

    • For backup clients of the latest version

      Linux: /opt/alibabacloud/hbrclient

      Windows: C:\Program Files\Aliyun Hybrid Backup Service Client

  3. Create a file named hbr.config in the client folder.
    Note The hbr.config file must be at the same directory level as the ids file.
  4. In the hbr.config file, set the following parameters for the cache feature.
    Parameter Description
    disable_blob_cache Specifies whether to cache data entry IDs. Valid values:
    • true: Data entry IDs are cached.
    • false: Data entry IDs are not cached.
    max_blob_cache_weight The maximum system memory that can be used by the cache for data entry IDs. Default value: 0.15. It indicates 15% of the total system memory. The value must be between 0 and 1.
    cache_prefix The path in which the cached data entry IDs are stored. The value must be an absolute path.
    max_retain_count The maximum number of cached data entry IDs.
    disable_file_cache Specifies whether to cache metadata. Valid values:
    • true: Metadata is cached.
    • false: Metadata is not cached.
    file_cache_max_size_hint The maximum size of a metadata cache file. The actual size may exceed the specified value. Default value: 2 GB.
    • If you set the parameter to 2 GB, a minimum of 4 TB data can be backed up.
    • If you set the parameter to a small value, the backup does not fail but the cache performance is degraded.
    • The value of the parameter cannot exceed the available disk space.


The following example shows the configurations of the hbr.config file:

disable_blob_cache = false
max_blob_cache_weight = 0.15
cache_prefix = D:\CacheFolder
max_retain_count = 16 

disable_file_cache = false
file_cache_max_size_hint = 2GB