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Learn about NVMe copy offload

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NVMe copy offload enables an NVMe host to offload copy operations from its CPU to the CPU of the ONTAP storage controller. The host can copy data from one NVMe namespace to another while reserving its CPU resources for application workloads.

Suppose, for example, that you need to rebalance your storage workloads to improve performance distribution. This requires you to migrate ten virtual machines (VMs) containing 45 NVMe namespaces with an average size of 500 GB each. This means you need to copy around 22.5 TB of data. Instead of using its own CPU for data migration, the host can use NVMe copy offload to avoid reducing its CPU resources for application workloads while the data is being copied.

NVMe copy offload support and limitations

NVMe copy offload is supported beginning with ONTAP 9.18.1. ONTAP cannot initiate NVMe copy offload; it must be supported and initiated by the host.

The following limitations apply to NVMe copy offload operations with ONTAP:

  • The maximum supported copy operation size is 16MB.

  • Data can be migrated only between NVMe namespaces within the same subsystem.

  • Data can be migrated only between nodes in the same HA pair.