HP-UX Mass Storage Stack - Hardware Path Aliasing

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HP-UX Mass Storage Stack – Hardware

Path Aliasing

Technical white paper

Table of contents

Abstract.............................................................................................................................................. 2

ioscan command alias_path property..................................................................................................... 2

New scsimgr attributes ......................................................................................................................... 3

Valid hardware path alias names .......................................................................................................... 3

Default hardware path aliasing scheme.................................................................................................. 3

HBA objects .................................................................................................................................... 4

Target path objects........................................................................................................................... 4

Lunpath objects................................................................................................................................4

LUN objects..................................................................................................................................... 5

Enabling and disabling the default scheme ......................................................................................... 5

Setting hardware path aliases manually ................................................................................................. 5

Software requirements.......................................................................................................................... 7

Glossary............................................................................................................................................. 7

For more information.......................................................................................................................... 10

Send comments to HP......................................................................................................................... 10

Summary of content (10 pages)

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HP-UX Mass Storage Stack – Hardware Path Aliasing Technical white paper Table of contents Abstract.............................................................................................................................................. 2 ioscan command alias_path property..................................................................................................... 2 New scsimgr attributes ...........................................................................................................
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Abstract This document describes the Hardware Path Aliasing feature contained in the HP-UX 11i v3 Mass Storage subsystem. The hardware path name associated with mass storage objects is currently represented as a long string of numbers, and the forward slash (/) and period (.) delimiters. This name can be very long and difficult to remember. For example, a hardware path for a lunpath is 0/4/2/0.0x500508b300903331.0x16000000000000.
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New scsimgr attributes The following scsimgr attributes were introduced in the initial release of the hardware path aliasing feature: • hwp_abs_alias • hwp_comp_alias These new attributes are applicable for HBA, target path, lunpath, and LUN objects. Similar to existing scsimgr attributes, these attributes are managed with the scsimgr get_attr, set_attr, and save_attr commands. By default, these attributes values are set to NULL strings.
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# scsimgr save_attr -Cdisk -I1 -a hwp_abs_alias=mpt0 class instance hwpath alias disk 1 64000/0xfa00/0x0 mpt0 In this scenario where a user-defined alias path is conflicting with the alias created using the default scheme, the first object to register is assigned the given alias path and the alias of the other object that is assigned the same hwpath alias is set to NULL. # scsimgr save_attr -a hwp_alias_enable=default Value of attribute hwp_alias_enable saved successfully Then, reboot the system.
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3. The default hardware path alias is class instance # with no space between the two. For example, fcd1.tport1.disk2. This is a component alias because it comes after the HBA and target path in the hardware path and assumes both to already be aliased. LUN objects 1. The saved hwp_abs_alias value is used (if it exists) as the absolute alias. 2. The saved hwp_comp_alias value is used (if it exists) as the component alias. 3. The saved alias attribute is used (if it exists) as the component alias. 4.
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overwrite the aliases with the scsimgr save_attr or scsimgr set_attr command. If hwp_alias_enable is set to false (0), you have some flexibility in assigning aliases. For example, you might choose to set absolute aliases at the target path or lunpath level, instead of the HBA level in the default scheme.
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# scsimgr save_attr –H fcd0.MSA_36.0x401d00000000000 –a hwp_abs_alias=default A mass storage object can only have one hardware path alias attribute defined at a time. Therefore, if hwp_abs_alias is set for an object, the hwp_comp_alias is NULL and vice-versa. The use of the hwp_abs_alias and hwp_comp_alias attributes must be mutually exclusive.
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Hardware path A series of numbers representing the physical or virtualized location of a device. HBA Host Bus Adapter HBA hardware path Hardware path to an HBA. In the agile view of the I/O tree, the HBA hardware path has the following format: hba_path. HPA Hardware Path Aliasing I_T nexus As defined by the T10 SAM standard, a nexus between a SCSI initiator port and a SCSI target port. I_T_L nexus As defined by the T10 SAM standard, a nexus between a SCSI initiator port, a SCSI target port, and a LUN.
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The hardware path to a target path. In the agile view of the I/O tree, the target path hardware path has the following format: hba_path.Target port WWN or Target Id Virtual HBA Virtual Host Bus Adapter. With N_Port ID Virtualization (NPIV), you can assign multiple N_Port IDs to a single N_Port. This makes a single Fibre Channel port appear as multiple virtual ports, each having its own N_Port ID and virtual WWN. Virtual HBA hardware path Hardware path to a Virtual HBA.
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For more information To read more about HP-UX mass storage, go to http://www.hp.com/go/hpux-core-docs. Click on the HP-UX version you want. Then, scroll down to the White papers section. Send comments to HP HP welcomes your input. Please give us comments about this white paper, or suggestions for the mass storage or related documentation, through our technical documentation feedback website: http://www.hp.com/bizsupport/feedback/ww/webfeedback.