Logical units and target ports on FlashSystem systems

For FlashSystem™, logical units are enumerated devices that have the same characteristics as LUNs.

LUNs

The FlashSystem™ system has a maximum LUN size of 40 TB.

The FlashSystem™ system can export 512 LUNs to the Lenovo Storage V series system, which is the Lenovo Storage V series limit. Lenovo Storage V series supports greater than 2 TB LUNs.

LUN IDs

The FlashSystem™ system identifies exported logical units through SCSI identification descriptor type 3. The 64-bit NAA IEEE Registered Extended Identifier (NAA=6) for the logical unit is in the form 6-OUI-VSID. For example, the model 9840-AE1 IEEE company ID is 005076 (IBM). The remaining part of the company ID is a vendor-specific ID.

 # lsmdisk 121
id 121
name mdisk121
status online
mode managed
mdisk_grp_id 8
mdisk_grp_name texan2
capacity 50.0GB
quorum_index 
block_size 512
controller_name texan2
ctrl_type 4
ctrl_WWNN 500507605EBFECC0
controller_id 19
path_count 32
max_path_count 32
ctrl_LUN_# 000000000000000D
UID 6005076001810000000000001900001b00000000000000000000000000000000
preferred_WWPN 
active_WWPN many
fast_write_state empty
raid_status 
raid_level 
redundancy
strip_size 
spare_goal
spare_protection_min
balanced 
tier generic_hdd
slow_write_priority
fabric_type fc
site_id 
site_name 
 #

Configuration, logical drives, and hosts

Use the default settings unless you need to use specific values. The FlashSystem™ wizard provides a default storage pool from which the volumes can be provisioned. If you are using the command-line interface (CLI), enter the following command:

svctask mkarray -level raid0/5

A storage pool is provisioned automatically from which the volumes can be provisioned and presented to the system.

Generally, it is best to provide a few large LUNs to the system (4 or 8) from the available capacity.

For more information, see the following Redbooks publication:

http://www.redbooks.ibm.com/redbooks.nsf/redbookabstracts/tips1079.html?Open&c4#contents

LUN presentation

LUNs are exported through the available FC ports of the FlashSystem™ storage system. Do not use the default open mapping unless the system has guaranteed sole access to the FlashSystem™. Use explicit host masking for the LUNs. Explicit is the preferred and safest method. See the information about the FlashSystem™ command:

svctask chsystem -openaccess off

Special LUNs

There are no special considerations for logical unit numbering. LUN 0 can be exported where necessary.

Target ports

An FlashSystem™ storage system can have a total of 16 8 GB Fibre Channel ports.

The following example shows the Fibre Channel ports on a controller:

 # lscontroller
id controller_name ctrl_s/n             vendor_id            product_id_low       product_id_high
19 texan2          000060400000-0000-0  IBM                  FlashSys             tem-9840

# lscontroller 19
id 19
controller_name texan2
WWNN 500507605EBFECC0
mdisk_link_count 15
max_mdisk_link_count 512
degraded no
vendor_id IBM
product_id_low FlashSys
product_id_high tem-9840
product_revision 1103
ctrl_s/n 000060400000-0000-0 
allow_quorum yes
fabric_type fc
site_id 
site_name 
WWPN 500507605EBFECE4
path_count 120
max_path_count 4096
WWPN 500507605EBFECC4
path_count 120
max_path_count 4096
WWPN 500507605EBFECD4
path_count 120
max_path_count 4096
WWPN 500507605EBFECF4
path_count 120
max_path_count 409
 #

Model 9840-AE1 WWNN and WWPN settings display as shown in the following example:

5005076SSSSSSSPP
5                  -   IEEE 803.2  ID NAA format,
005076       -   IEEE unique VSID for IBM. (common with SVC)
SSSSSS      -   unique vendor-supplied serial number for the device. 
PP              -  vendor specific code used to identify specific ports 
WWNN 500507605EBFF2C0 
WWPN 500507605EBFF2E1 
WWPN 500507605EBFF2D1 
WWPN 500507605EBFF2C1 
WWPN 500507605EBFF2F1

LU access model

All systems are Active/Active. To avoid an outage from system failure, cross connect the ports across Fibre Channel switches. Because all FlashSystem™ storage systems are equal in priority, you gain no benefit by using an exclusive set for a specific LU.

LU preferred access port

No access ports are preferred on the FlashSystem™ system because all ports are Active/Active across all systems.

Detecting Ownership

Detecting ownership does not apply to FlashSystem™ storage arrays.

Logical units and target ports on FlashSystem™ systems