NEC PathManager

Chapter 3 Functions of NEC Storage PathManager

of their number. For other logical units, the paths will be displayed in the order of priority. If not

specifically set, this display order will be applied.

- s1: Paths will be displayed in the order of their number.

- s2: Paths will be displayed in the order of priority.

The following image shows a display example when the -s1 option is used.

C:\>spscmd -getlun -s1

*** LogicalUnit #0 ***

> 0: Priority=2, PathNumber=4:0:0:0

1: Priority=1, PathNumber=5:0:1:0

*** LogicalUnit #1 ***

X 0: Priority=1, PathNumber=4:0:0:1

> 1: Priority=2, PathNumber=5:0:1:1

+++ LogicalUnit #2 +++ [round robin]

@ 0: Priority=1, PathNumber=4:0:0:2

> 1: Priority=2, PathNumber=5:0:1:2

C:\>

As seen in the above image, the paths are displayed in the order of their number for the logical unit #2.

3.2 Path control

Path control is a function to specify the state of each path managed by NEC Storage PathManager. Use an

spscmd to use this function. Path priority, which becomes important when controlling the paths, will be

described first. Then spscmd options to be used in path control will be desc ribed.

.2.1 P

ath priority

3.2

Path priority is assigned to each path in each logical unit and is used to specify the order of path s to be

used in the respective logical units. Priority is expressed as an integer between 1 and 254 and is uniquely

determined in each logical unit. Priority becomes higher as the number becomes lar ger.

Path priority is mainly used to determine which path is to be used as an alternative in case of failures in the

path currently being used. Therefore, the path with the highe st priority will be first used. However, when

failures occur in this path, then the path with the second highest priority will be used.

When loads are dynamically distributed (in the round robin method), path priority is used to dete rmine the

order of multiple paths to be used in dynamic load balancing. This means that the paths will be used in the

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