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Hitachi Vantara Knowledge

Using cluster name space (CNS)

The CNS has a tree-like directory structure, much like a real file system. Its virtual root and subdirectories provide access to file systems. The CNS can be viewed through the CLI or the NAS Manager, and shows all of the configured directories and file system links.

CNS usage considerations

The following recommendations are intended to simplify configuration and maintenance for CNS and for transfers of primary access for the file system:

  • A single name space is supported per server or cluster.
  • If there is only one CNS link to the file system, and no CIFS shares/NFS exports on the file system, only a single link has to be moved during a transfer of primary access.
  • CNS does not support hard links or move operations across the individual file systems. These operations are fully supported, but only within a single physical file system; that is, the part of the CNS tree under a file system link.
  • Relocating file systems under the CNS may interrupt CIFS access to the file system being relocated. To minimize interruption, relocate file systems when they are idle. For more information, refer to the Replication and Disaster Recovery Administration Guide.
  • When using CNS and EVS together:
    • Only one EVS per cluster node is required for all data inside the cluster name space. Having additional EVSs causes unnecessary administrative overhead, and may lead to confusion. Use multiple EVSs on the same cluster node only when you have data that should reside outside the cluster name space.
    • Balance loads by moving file systems, instead of migrating EVS. If you migrate an EVS containing a read cache, the files in the read cache become invalidated and, assuming they are still cacheable, they would have to be cached again after the next read request.

      If an EVS containing a read cache is migrated to another cluster node that already has a read cache, the files in the migrated read cache are invalidated, and only the read cache that was not migrated will be used. If the EVS is migrated back to its original cluster node, the read cache will be used again, assuming another read cache has not been created on that cluster node in the interim.

  • When using CNS, the recommended configuration is to have a single CIFS share or NFS export at the root of the name space. If that configuration does not suit your needs, the next best configuration is to have CIFS shares/NFS exports pointing to individual directories in the name space. You should not configure CIFS shares or NFS exports pointing to a path of the real file system unless absolutely necessary.
    NoteA VSP Gx00 or Fx00 with NAS modules is a two node cluster in a single chassis. The CNS support on the default two node cluster is automatic. Both nodes have access to the shared storage, and the CNS traffic is sent to the other node.

Displaying the cluster name space tree

  1. Navigate to Home Files Services CNS to display the CNS page.

  2. If a secure EVS has been created and you want to display the EVS name space for that secure EVS, click change to select the name space you want to display.

    After you have selected a name space, the tree for that context is displayed.
    • At the top of the name space is the root directory.
    • Under the root directory are a number of subdirectories. In this example topology, one subdirectory has been created for each physical file system.
    • Under each subdirectory is a file system link. A file system link associates a directory with a specific file system. The EVS to which the file system is associated is also shown.

Displaying the EVS name space tree

  1. Navigate to Home File Services CNS to display the CNS page.

    The currently selected EVS security context and the current name space are displayed at the top of the page, and the tree for the current name space is displayed below the name space label.
  2. Click change to display a list of name spaces (the Global Configuration, and all individual EVS name spaces that have been defined).

  3. Click Global Configuration or the EVS name space to display the tree for that name space.

    • At the top of the name space is the root directory.
    • Under the root directory are a number of subdirectories. In this example topology, one subdirectory has been created for each physical file system.
    • Under each subdirectory is a file system link. A file system link associates a directory with a specific file system. The EVS to which the file system is associated is also displayed.

Managing links and subdirectories in the EVS name space

Links and subdirectories in an individual EVS name space are managed in the same way as they are in the CNS.

Creating a cluster name space tree

A CNS contains a root directory, file system links, and, optionally, subdirectories. The first step required to configure CNS is to create the root directory.

Creating a CNS root directory

  1. Navigate to Home File Services CNS to display the CNS page.

  2. In the CNS Root Label text box, enter a name, and click OK to create the CNS.

    NoteFor the CNS to be available to clients, a CIFS share or an NFS export must be created for it. See the File Services Administration Guide.

Creating CNS subdirectories

Subdirectories can be created under the root directory or under other subdirectories in the CNS tree. Subdirectories are optional, but they give structure to the CNS, allowing granular control over the organization of physical file system resources.

Procedure

  1. Navigate to Home File Services CNS to display the CNS page.

  2. Click Add Directory to display the Add CNS Directory page.

  3. From the Select a Parent for the Directory options box, select a parent directory, and enter a name in the Subdirectory Name text box.

  4. Click OK to create the subdirectory, and repeat to add any additional subdirectories.

Creating a file system link

File system links make physical file systems accessible through the CNS. A file system link can be associated with either the root directory or a subdirectory in a physical file system. After created, a file system link is displayed as a directory in the CNS. The directory name seen by a network client will be the name given to the file system link. A network client navigating through CNS and into a file system link will see the contents of the directory that was linked.

Procedure

  1. Navigate to Home File Services CNS to display the CNS page.

  2. Click Add Link to display the Link File System page.

  3. In the Link Name text box, enter a name for the link.

  4. In the From CNS Directory options box, select a location in the CNS tree to place the link.

  5. To allow files or cross file system links from remote file systems to be read cached, go to the Remote Read Cache list, and select one of the following:

    NoteFor information about read caching, see the File Services Administration Guide.
    • Cache all files. Allows caching of files from a file system hosted by an EVS on a remote cluster node, and files accessed by local links to a remote file system (cross file system links). A remote cluster node is a node other than the one to which the client is connected.
    • Cache cross file system links. Allows only cross file system links to be cached.
    NoteWhen the link being added is for a file system in an EVS that has an EVS individual namespace, remote read caching is not available.

    To disallow read caching of files from remote file systems, do not change the default selection of Do not cache files.

  6. To allow files or cross file system links from local file systems to be read cached, go to the Local Read Cache list, and select one of the following:

    • Cache all files. Allows caching of files from file systems on the same server/node as the read cache, and files accessed by local links to a remote file system (cross file system links). The remote file system might be a remote server or storage device.
    • Cache cross file system links. Allows only cross file system links to be cached.
    To disallow read caching of files from remote file systems, do not change the default selection of Do not cache files.

Changing cluster name space properties

After a CNS has been created, any of its properties can be changed, except the name of the root directory.

Deleting a cluster name space

Deleting a CNS permanently erases it. Deleting a CNS does not affect the physical file systems accessible through the CNS. However, once the CNS has been deleted, it may be necessary to restore access to the file system by sharing or exporting the file system through its EVS.

Procedure

  1. Navigate to Home File Services CNS to display the CNS page.

  2. From the CNS directory tree, select the CNS root directory, and click remove to open a confirmation dialog.

  3. Click OK to delete the CNS.

Renaming a CNS subdirectory

  1. Navigate to Home File Services CNS to display the CNS page.

  2. From the CNS directory tree, select the subdirectory to be renamed, and click modify to display the Modify CNS Directory page.

  3. In the Subdirectory Name text box, enter a new name for the CNS directory, and click apply to open a confirmation message box.

  4. Click OK to rename the directory.

Moving a CNS directory

Moving a CNS directory from one location in the CNS to another can be done at any time.

Procedure

  1. Navigate to Home File Services CNS to display the CNS page.

  2. From the CNS directory tree, select the subdirectory to be moved, and click modify to display the Modify CNS Directory page.

  3. From the Select a Parent for the Directory options box, select a new location in the CNS tree. From the bottom of the options box, click apply to open a confirmation message box.

  4. Click OK to move the directory.

Deleting a CNS directory

Deleting a CNS directory permanently removes it and all of its subdirectories and file system links. Deleting CNS directories does not affect physical file systems on the server.

Procedure

  1. Navigate to Home File Services CNS to display the CNS page.

  2. From the CNS directory tree, select a subdirectory.

  3. From the box at the bottom of the page, click remove to open a confirmation message box.

  4. Verify your settings, and click OK to proceed, or cancel to decline.

Modifying a file system link

The name and location of a CNS file system link can be modified.

Procedure

  1. Navigate to Home File Services CNS to display the CNS page.

  2. From the CNS tree, select a file system link, and click modify to display the Modify Link page.

  3. As needed, change the link name or parent directory.

    • To change the name of the file system link, enter the new name in the Link Name text box, and click apply.
    • To change the parent directory, select a new location in the tree from the Select a New Parent Directory options, and click apply.
  4. If necessary, change the setting to enable or disable the caching of files from this file system, and click apply.

Deleting a file system link

Procedure

  1. Navigate to Home File Services CNS to display the CNS page.

  2. From the CNS tree, select a link, and click remove to display a confirmation dialog.

  3. Click OK to proceed.

 

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