addvdiskaccess

Use the addvdiskaccess command to add one or more I/O groups to the set of I/O groups in which a volume can be made accessible to hosts.

Note: IBM FlashSystem does not support systems with more than one I/O group. IBM SAN Volume Controller systems continue to support multiple I/O groups on long-term support releases only. FlashSystem grid can be used to scale out a storage system.

Syntax

Read syntax diagramSkip visual syntax diagram addvdiskaccess -iogrp  iogrp_id_listiogrp_name_list -allowmismatchedscsiids vdisk_idvdisk_namevdisk_uid

Parameters

-iogrp iogrp_id_list | iogrp_name_list
(Required) Specifies a list of I/O groups to add to the I/O group volume access set.
-allowmismatchedscsiids
(Optional) When you add new access I/O groups, this parameter allows the SCSI LUN IDs to be different from the currently assigned SCSI LUN IDs in existing access I/O groups.
vdisk_id | vdisk_name | vdisk_uid
(Required) Specifies the volume to which to add access through the specified I/O groups.

Description

If an I/O group is already a member of the access set, no error is generated and no action is taken for that I/O group. All host mappings for the volume are added to the I/O groups in the list. The -force option is not required to extend additional mappings to other I/O groups.

When an I/O group is added to the access set, access is granted to the volume from the hosts that are mapped to the volume from the nodes in the I/O group. If the volume is mapped twice, it is also mapped twice through all additional I/O groups.

You can add I/O groups to the volume access list if the groups are mapped to iSCSI hosts. This means that iSCSI hosts can access volumes that are accessible through single or multiple I/O groups.

Two mappings are created if a host is mapped to a volume with two I/O groups. Hosts are limited to 512 host-to-volume mappings, which means a host can be mapped to the following volumes:
  • 512 volumes in a single I/O group
  • 256 volumes across two I/O groups
  • 64 volumes across four I/O groups
Restriction:

The -addvdiskaccess command fails if one or more of the following issues exist:

  • The host (for which the volume has a host mapping) is not associated with an I/O group in the list.
  • The host volume mapping limit is exceeded.
  • The number of extra mappings that are added exceeds the clustered system limit for host volume mappings.
  • The same SCSI LUN ID is not available in the new access I/O group.

The system assigns the same SCSI LUN ID allocated to the volume in other access I/O groups if it is available in the new access I/O groups. Using the -allowmismatchedscsiids parameter allows the system to allocate non-identical SCSI LUN IDs in the access I/O group. The lowest value available in each access I/O group is used. It might not be the same in all access I/O groups. Ensure that the host supports this configuration. This parameter is not supported for NVMe hosts. When a volume is mapped to a host that uses the NVMe protocol, the volume namespace ID (NSID) is assigned by the system. When you add access to a volume that already has different SCSI LUN IDs in its existing access I/O group, you must enable the -allowmismatchedscsiids parameter, or the command fails.

An invocation example

This example adds I/O group 2 to the volume access set for DB_Volume:

addvdiskaccess -iogrp 2 DB_Volume

The resulting output:

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