System requirements

Software license

The ShadowImage software license must be installed on the storage system.

License capacity

The capacity of P-VOLs and S-VOLs must be less than or equal to the installed license capacity. Volume capacity is counted only once, even if you use a volume more than once. You do not need to multiply the capacity by the number of times a volume is used. For example, a volume used as a P-VOL for three pairs is counted only once.

For an internal or external volume, the total volume capacity is counted. For a DP-VOL, the pool capacity being used by the volume is counted. For a volume with capacity saving enabled, the licensed capacity is the data capacity before saving. If the available licensed capacity will be exceeded when you create a pair, the pair create operation will fail.

After you start performing pair tasks, monitor your capacity requirements to keep the used capacity within the capacity of the installed license.

You can continue using ShadowImage volumes in pairs for 30 days after licensed capacity is exceeded, regardless of whether an external volume or a DP-VOL is used. After 30 days, the only allowed operation is pair deletion. The problem of exceeding the licensed capacity can be resolved by reducing the capacity to less than or equal to the licensed capacity. However, the warning message will remain displayed. The warning message is updated once a day, therefore when the problem is resolved, the warning message will automatically disappear within 24 hours.

For more information about licenses, see the System Administrator Guide.

User interfaces

• VSP One Block Administrator

  VSP One Block Administrator supports ShadowImage operations.

• Command Control Interface (CCI) supports ShadowImage operations. The CCI software must be installed on a connected host. Embedded CCI (Command Console) does not support ShadowImage operations.

  If a logical volume assigned as a namespace on an NVM subsystem with the NVMe-oF connection is specified as a P-VOL or an S-VOL of a ShadowImage pair, CCI must be used.

• REST API

Pair volumes

• Supported volume types:
  • Internal volumes
  • External volumes
  • Customized volumes (CVs) that are created using Virtual LVI/LUN
• (VSP One B85) Emulation type: The supported emulation type is the same as when the pair status is SMPL. The P-VOL and S-VOL must have the same emulation type.
• Volume capacity: The P-VOL and S-VOL must have the same capacity in blocks.

  If the capacity is displayed in GB or TB, a small difference between P-VOL and S-VOL capacity might not be displayed. Change the display to show capacity in blocks.

• The following volumes cannot be used as pair volumes:
  • UR journal volumes
  • Pool volumes
  • Virtual volumes except Dynamic Provisioning volumes (DP-VOLs)
  • Deduplication system data volumes (DSD-VOLs)
  • Data reduction shared volumes (DRS-VOLs)
• T10 PI attribute: The value of the T10 PI attribute must be the same for the P-VOL and the S-VOL.
• LU paths or namespaces on the NVM subsystem with an NVM subsystem port added for NVMe must be defined on both the P-VOL and S-VOL.

  In addition, while the P-VOL and S-VOL are used as paired volumes, at least one LU path or namespaces on the NVM subsystem with an NVM subsystem port added for NVMe must be defined on both the P-VOL and S-VOL.