Allocating volumes to compute nodes

Precautions applicable to all connection protocols

• When using VMware ESXi as a compute node, set up a path between the compute node and all computer ports when registering path information of the compute node. Unless all paths have been set, some volumes might not be visible from a compute node.

  If VMware ESXi is not used as a compute node, set up a path between the compute node and all computer ports to prevent deterioration in I/O performance.

  For how to set up a path, see Registering path information about compute nodes.

• If you have changed the connection information between a volume and compute node, perform a rescan of the storage in that compute node before you start I/O operations.

• Processing performance when registering volume paths

  The processing time varies depending on the number of volume paths registered on the applicable compute node.

  • When registering the first volume path, the processing completes in one or two seconds.

  • For every 1,000 registered volume paths, the processing time for registering one volume path will increase by 1 to 2 seconds.

  • When registering the 8,192nd volume path (upper limit), the processing takes approximately 15 seconds.

Precautions for using FC or iSCSI connection

• If you specify a volume path without specifying lun or startLun, the smallest LUN that is not used is automatically assigned. However, if multiple volume paths are concurrently set without specifying lun or if volume paths are set for multiple volumes, LUNs might not be assigned in the ascending order in which they were set. To assign a specific LUN, set a volume path by specifying lun.
• If some volumes cannot be recognized by the OS, the system might behave as follows. Resolve the state where volumes cannot be recognized, and then perform a rescan of the storage in the compute node.

  • During recognition of LUNs in the order from the smallest, if an unrecognizable LUN exists, LUN recognition stops.

  • When LUN = 0 cannot be recognized, LUN recognition stops.

Precautions for using NVMe/TCP connection (Virtual machine)(Bare metal)

• Volumes for which volume paths are set can be recognized as NVMe devices from a compute node. NVM subsystems and namespaces included in NVM device control information are automatically allocated on the storage side. They can be referenced after volume paths are set.

  For details about allocating NVM subsystems and namespaces, see System configuration when NVMe/TCP connection is used.

• If some or all of the volumes cannot be recognized, verify that the compute node is connected to the storage node, and then rescan the storage on the compute node.