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Hitachi Vantara Knowledge

Expanding storage pools

To expand a storage pool without using Hitachi Dynamic Provisioning, add SDs to the storage pool. If the storage pool is tiered, you can add SDs to one tier without adding SDs to the other tier. To see how full each tier is, use the span-list --sds command.

If you are using Hitachi Dynamic Provisioning, see the Hitachi NAS Platform HDP Best Practices (MK-92HNAS063) for recommendations.

Expanding space in a thinly provisioned HDP storage pool

You can easily add space to a storage pool that uses thin-provisioned HDP.

The pool formatting process is non-disruptive, so the file systems stay mounted during the process.

NoteFor detailed information about specific commands and how they are used, see the CLI man pages or the Command Line Reference.


  1. Create the pool volumes.

  2. Use the span-confine command to confine the span.

  3. Add the pool volumes to the HDP pool.

    Adding the pool volumes automatically enables the Optimize check box on Hitachi Midrange storage systems.
  4. Wait for the pool to finish formatting.

  5. If required, use the span-release command to release the span on the HNAS system.

    The HNAS system auto-detects the new space and lets you use it in new or existing file systems.
  6. Check that the real disk space in the pool still does not exceed the total capacity of the pool's DP-Vols.

Expanding storage space using DP-Vols

Eventually, the total size of the HDP pool volumes reaches the total size of the DP-Vols. If the NAS server storage pool (span) needs more space, you can add space to it.

You can add as many HDP pool volumes as you want; however, you typically only need to add a small amount of space.

NoteSee the CLI man pages or the Command Line Reference for detailed information about commands.


  1. Add the new pool volumes to the original pool.

  2. If the new total capacity of the pool volumes exceeds that of the DP-vols, add more DP-vols to the same HDP pool.

    NoteMake the new DP-Vols the same size and number as you originally created. All stripesets must be the same.
  3. Wait for formatting to finish.

    Otherwise, the file systems may auto-expand onto the new storage and find it so slow that the entire span fails.
  4. If new DP-vols were created, use the span-expand command to expand the span on to the new DP-Vols.

Expanding a non-HDP storage pool or tier

  1. Navigate to Home Storage Management Storage Pools to display the Storage Pools page.

  2. Select the check box next to the label of the storage pool you want to expand, and click details.

    For an untiered storage pool, the Storage Pool Details page shows File System and Hosting System Drive details:

    Storage Pool Details

    For a tiered storage pool, the Storage Pool Details page shows the stripeset information and the specific System Drives in each tier. Clicking on a drive shows System Drive details:

  3. To display the available system drives to add to the storage pool, click expand. To display the available system drives to add to a tier, select the tier you want to expand, and click expand. The Storage Pool Wizard page is displayed.

  4. Select the check box next to the label of the system drive you want to add, then click next to display the next Storage Pool Wizard page.

  5. Click expand to add the SDs to the storage pool/tier.