Chapter 9 Setting The Multipaths; Multipath Configuration Using Pv-Links - Fujitsu ETERNUS AF Configuration Manual

Chapter 9
Setting the Multipaths
Three types of multipath configurations are available for the connection between the ETERNUS AF/DX and an
HP-UX server:"PV-Links", "Native Multipaths", and VxVM's "DMP".
This chapter explains how to set up the HP-UX default "PV-Links" or "Native Multipaths". Refer to the Syman-
tec Corp. documentation for VxVM's "DMP" details.
9.1

Multipath Configuration Using PV-Links

"PV-Links" is a Logical Volume Manager (LVM) function that is available for all HP-UX versions.
LVM for HP-UX supplies PV-Links as a standard function for configuring paths in a redundant configuration
(path failover function).
PV-Links is set by including multiple paths connected to one physical volume in one volume group.
Only one of the paths will be set as the Active path, with the other paths being made Standby paths.
However, load on the system may be better balanced by spreading the server accesses over multiple Active
paths.
PV-Links are only available for LVM configurations.
When using PV-Links, note the following:
Confirm that the PV-Links paths have identical target IDs.
•
For a direct connection, confirm that the PV-Links paths have identical target IDs. Confirm that the PV-Links
paths have identical target IDs, by checking the ETERNUS AF/DX CA port settings for each PV-Link path and
comparing the target IDs.
When set correctly, the device files for all paths that connect to a given ETERNUS AF/DX LUN should all be
the same after the "t" part of the name (e.g. "/dev/dsk/c4t0d0" g "0d0").
• Disable Native Multipaths when HP-UX11iv3 is used.
For HP-UX11iv3, Native Multipaths are enabled by default. To enable PV-Links equivalent operation, the
Native Multipaths must be disabled.
Native Multipaths are disabled by setting the "leg_mpath_enable" parameter to "false" and using Legacy
DSF for access.
Native Multipaths are always enabled when using Persistent DSF access.
Reference
-
Device special file type
Legacy DSF
Persistent DSF
FUJITSU Storage ETERNUS AF, ETERNUS DX Configuration Guide -Server Connection- (Fibre Channel) for HP-UX
Example device special file
/dev/dsk/c4t0d0
/dev/rdsk/c4t0d0
/dev/disk/disk25
/dev/rdisk/disk25
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