Logical units and target ports on IBM® XIV Storage System models

On IBM® XIV® Storage System, logical units (LUs) are enumerated devices that have the same characteristics as LUNs.

LUNs

An IBM® XIV® Storage System Logical Unit is referred to as a volume. IBM® XIV® Storage System and volumes are enumerated devices that all share identical characteristics.

A single IBM® XIV® Storage System volume can potentially consume the entire capacity that is allocated for the system storage pools. It can also exceed the system 1 PB LUN size limit. Any LUN that is 1 PB or larger is truncated to 1 PB, and a warning message is generated for each path to the LUN.

IBM® XIV® Storage System volumes consume chunks of 17,179,869,184 bytes (17 GB), although you can create volumes with an arbitrary block count.

LUN IDs

LUNs that are exported by IBM® XIV® Storage System models report Identification Descriptors 0, 1, and 2 in VPD page 0x83. The system uses the EUI-64 compliant type 2 descriptor CCCCCCMMMMMMLLLL. In the descriptor, CCCCCC is the IEEE company ID, MMMMMM is the System Serial Number that is transcribed to hexadecimal (10142->0x010142, for example) and LLLL is 0000-0xFFFF, which increments each time a LUN is created. You can identify the LLLL value by using the IBM® XIV® Storage System GUI or CLI to display the volume serial number.

LUN creation and deletion

IBM® XIV® Storage System LUNs are created and deleted by using the IBM® XIV® Storage System GUI or CLI. LUNs are formatted to all zeros upon creation; however, to avoid a significant formatting delay, zeros are not written.

Special LUNs

IBM® XIV® Storage System systems do not use a special LUN; storage can be presented by using any valid LUN, including "0".

LU access model

IBM® XIV® Storage System systems have no specific ownership of any LUN by any module. Because data is striped over all disks in the system, performance is generally unaffected by the choice of a target port.

LU grouping

IBM® XIV® Storage System models do not use LU grouping; all LUNs are independent entities. To protect a single IBM® XIV® Storage System volume from accidental deletion, you can create a consistency group that contains all LUNs that are mapped to a single system.

LU preferred access port

No access ports are preferred for IBM® XIV® Storage System models.

Detecting ownership

Ownership is not relevant to IBM® XIV® Storage System models.

LUN presentation on XIV Nextra systems

XIV® Nextra™ LUNs are presented to the system interface by using the following rules:
  • LUNs can be presented to one or more selected hosts.
  • XIV® Nextra™ maps consist of sets of LUN pairs and linked hosts.
  • A volume can appear only once in a map.
  • A LUN can appear only once in a map.
  • A host can be linked to only one map.
To present XIV® Nextra™ LUNs to the system, complete the following steps:
  1. Create a map with all of the volumes that you intend to manage with the system.
  2. Link the WWPN for all node ports in the system into the map. Each system node port WWPN is recognized as a separate host by XIV® Nextra™ systems.

LUN presentation on IBM XIV Type Number 2810 systems

IBM® XIV® Storage System Type Number 2810 LUNs are presented to the system interface by using the following rules:
  • LUNs can be presented to one or more selected hosts or clusters.
  • Clusters are collections of hosts.
To present IBM® XIV® Storage System Type Number 2810 LUNs to the system, complete the following steps:
  1. Use the IBM® XIV® Storage System GUI to create an IBM® XIV® Storage System cluster for the system.
  2. Create a host for each node in the system.
  3. Add a port to each host that you created in step 2. You must add a port for each port on the corresponding node.
  4. Map volumes to the cluster that you created in step 1.

Target ports on XIV Nextra systems

XIV® Nextra™ systems are single-rack systems. All XIV® Nextra™ WWNNs include zeros as the last two hexadecimal digits. In the following example, WWNN 2000001738279E00 is IEEE extended; the WWNNs that start with the number 1 are IEEE 48 bit:
WWNN 2000001738279E00 
WWPN 1000001738279E13 
WWPN 1000001738279E10 
WWPN 1000001738279E11 
WWPN 1000001738279E12

Target ports on IBM XIV Type Number 2810 systems

IBM® XIV® Storage System Type Number 2810 systems are multi-rack systems, but only single racks are supported. All IBM® XIV® Storage System Type Number 2810 WWNNs include zeros as the last four hexadecimal digits, as shown in the following example: 
WWNN 5001738000030000
WWPN 5001738000030153
WWPN 5001738000030121
Parent topic: Configuring IBM XIV Storage System models