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Hitachi Vantara Knowledge

Creating a read cache file system

A read cache is a special read-only file system that stores copies of individual files outside of their local file systems, enabling a server or a node to have a cached copy of the file.


  1. Navigate to Home Storage Management File Systemsto display the File System page.

  2. Click Read Cache.

  3. Select a storage pool to contain the read cache, and then click next to display the Create Read Cache page.


    The following table describes the fields on this page:

    Field/Item Description
    Storage Pool Displays the name of the storage pool in which the read cache file system is being created.
    Free Capacity Amount Displays the available space in the storage pool that can be used by read cache file systems.
    Tier 0 Meta-data and Tier 1 User-data Displays the size of the storage pool’s metadata tier (Tier 0) and the user data tier (Tier 1).
    NoteThis information applies only to tiered file systems, and is not displayed for untiered read cache file systems.
    Guideline Chunk Size Displays the approximate size of the chunks used in the selected storage pool.


    The size of the read cache being created. Enter a size for the read cache.
    • For an untiered read cache, this defines the total size of the read cache.
    • For a tiered read cache, this defines the size of the user-data tier of the read cache.

    The size value can be changed on the File System Details page once the read cache has been created.

    Rounded Size Approximate size limit, based on the defined Size Limit and the chunk size defined for the storage pool.
    Label The label by which the read cache should be referenced.
    Assign to EVS The EVS to which the file system is assigned.
    Block Size Sets the optimal block size for the file system.
  4. Enter a Size Limit for the file system.

    This defines the maximum size to which the file system or user data tier can grow through Auto-Expansion. Once the file system has been created, this value can be changed on the File System Details page. This limit is not enforced for manual file system expansions performed through the CLI.
  5. The value in the Rounded Size Limit field is calculated automatically, but can be changed. For more information, click Rounded to nearest chunk. If the specified size is not a multiple of the chunk size, the server rounds down to the nearest chunk boundary.

  6. In the Label field, enter the name of the file system.

    File system labels are not case sensitive, but they do preserve case (labels will be kept as entered, in any combination of upper and lowercase characters). Also, file system labels cannot contain spaces or any of the following special characters: "&'*/;:<>?\|. File system labels must be unique within a server or cluster. Also, a file system cannot have the same label as a storage pool.
  7. From the EVS list, select the EVS to which the file system should be assigned.

  8. In the Block Size field, enter the desired file system block size.

  9. Click OK.


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