Logical units and target ports on Xiotech ISE systems
On Xiotech ISE systems, logical units (LUs) are enumerated devices that have the same characteristics as logical unit numbers (LUNs).
LUNs
An Xiotech ISE logical unit is referred to as a volume. Xiotech ISE volumes are enumerated devices that all share identical characteristics.
A single Xiotech ISE volume can potentially consume the entire capacity that is allocated for Storwize® V3700 storage pools, but it cannot exceed the Storwize V3700 2 TB LUN size limit. Any LUN that is 2 TB or larger is truncated to 2 TB, and a warning message is generated for each path to the LUN.
LUN IDs
LUNs that are exported by Xiotech ISE systems are guaranteed to be unique. They are created with a combination of serial numbers and counters along with a standard IEEE registered extended format.
LUN creation and deletion
Xiotech ISE LUNs are created and deleted by using either the Xiotech ISE Storage Management GUI or CLI. LUNs are formatted to all zeros at creation.
When a new LUN is created, the Xiotech ISE system begins a background zeroing process. If a read operation comes in to an area that has not been processed yet, the system returns zeros as a read response. This is the normal procedure. If a previous LUN with data was in that storage area, it is zeroed out. If a non-zeroed-out area gets read, the system returns zeros if it has not been written to yet.
LUN presentation on Xiotech ISE systems
- LUNs can be presented to one or more selected hosts.
- Configuration is easier if you create one host name for the Storwize V3700.
- No individual LUN volume on the Xiotech ISE system can exceed 2 TB in size.
- For the managed reliability features to be effective on the Xiotech ISE system, use either RAID 1 or RAID 5 when you create volumes.
- The write-back and write-through cache options are available depending on the performance requirements on each individual LUN. Generally, write-back caching provides the best performance.
- Although either Linux or Windows can be used, Linux is recommended for volumes that are intended for use on the Storwize V3700.
- On the Xiotech
ISE system,
create a single host name for the Storwize V3700 and
assign all Storwize V3700 host
bus adapter (HBA) ports to that host name as shown in Table 1.
Table 1. Host information for Xiotech ISE Name Operating system type HBA ports Mapping SVC_Cluster Linux 500507680130535F 5005076801305555 500507680140535F 5005076801405555
Volume01 (lun:1) Volume02 (lun:2)
- When you create new volumes that are intended for use on the Storwize V3700, assign them to the host name that is used to represent the Storwize V3700.
Special LUNs
The Xiotech ISE storage system does not use a special LUN. Storage can be presented by using any valid LUN, including 0.
Target ports on Xiotech ISE systems
ISE1 example:
ISE1 WWNN: 20:00:00:14:c3:67:3f:c4
MRC1 WWPN: 20:00:00:14:c3:67:3f:c4
MRC2 WWPN: 20:00:00:14:c3:67:3f:c5
ISE2 example:
ISE2 WWNN: 20:00:00:1F:93:10:31:78
MRC1 Port 1 WWPN: 20:00:00:1F:93:10:31:78
MRC1 Port 2 WWPN: 20:00:00:1F:93:10:31:79
MRC1 Port 3 WWPN: 20:00:00:1F:93:10:31:7A
MRC1 Port 4 WWPN: 20:00:00:1F:93:10:31:7B
MRC2 Port 5 WWPN: 20:00:00:1F:93:10:31:7C
MRC2 Port 6 WWPN: 20:00:00:1F:93:10:31:7D
MRC2 Port 7 WWPN: 20:00:00:1F:93:10:31:7E
MRC2 Port 8 WWPN: 20:00:00:1F:93:10:31:7F
LU access model
The Xiotech ISE system has no specific ownership of any LUN by any module. Because data is striped over all disks in a DataPac, performance is generally unaffected by the choice of a target port.
LU grouping
The Xiotech ISE system does not use LU grouping; all LUNs are independent entities.
LU preferred access port
There are no preferred access ports for the Xiotech ISE system.
Detecting ownership
Ownership is not relevant to the Xiotech ISE system.