> Expert > Storage > Data Path Management > Streams Overview > Multi-Stream Backup Operations

Setting the Data Readers for File System Agents

Data Reader determines the number of parallel read operations while the data is backed up.

Procedure

  1. From the CommCell Browser, expand Client Computers > client > File System > backup_set.

  2. Right-click the subclient and then click Properties.

    The Subclient Properties dialog box appears.

  3. In the Subclient name box, type the name of the subclient.

  4. On the Content tab, add the content to be backed up.

  5. Click Advanced.

    The Advanced Subclient Properties dialog box appears.

  6. On the Performance tab, select one of the following options:

    • Automatically use optimal number of data readers

      Applies to: Windows file system agent, UNIX file system agent, Laptop agent, and multi-node agents such as Network Shares, Hadoop, GPFS, GlusterFS, and LustreFS.

      Number of data readers is decided based on the size of the data and number of items in the dataset.

      Size of the data per access node = Total data size/Number of access nodes

      Data size (per node) File server File share
      2 GB - 10 GB 4 4
      10 GB - 100 Gb 4 8
      100 GB - 300 GB 8 16
      > 300 GB 8 24

      Total number of data readers = (Number of streams based on above table) * (Number of access nodes) * Stream multiplication factor

    • Number of Data Readers

      Enter the number of data streams in the Number of Data Readers box.

    Note

    • A maximum of 400 data streams are be used.

    • The number of streams used depends on the amount of new or changed data in a job, not the entire dataset size. For instance, a 2TB dataset with only a few megabytes of changes will not require 400 streams. This only affects new full backups with unique data or jobs with significant data modifications.

    • Stream multiplication is calculated and will be roughly between 1 and 3. It is calculated based on the number of items qualified for backup.

  7. Select the Allow multiple data readers within a drive or mount point check box.

    This option is enabled by default.

  8. Click OK.

  9. On the Storage Device tab, in the Storage Policy list, click a storage policy name to associate with the subclient.

    Tip: To create a new storage policy, click Create Storage Policy and follow the instructions in the storage policy creation wizard.

  10. Click OK.

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