HP-UX Mass Storage Stack - Hardware Path Aliasing

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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.
Some examples of manually assigning hardware path aliases are to incorporate the enclosure name
into the target path, lunpath, or lun hardware path alias, and to specify which disk is the system boot
or alternate boot disk.
Setting the hwp_abs_alias attribute replaces the entire hardware path with the attribute’s value. In
addition, all objects under the object having the attribute set inherit the absolute alias in their
alias_path property. For example, the following scsimgr command makes changes that you can
see in the ioscan command:
# scsimgr save_attr –H 0/3/1/0 –a hwp_abs_alias=fcd0
# ioscan –P alias_path
Class I H/W Path alias_path
==============================================================
fc 0 0/3/1/0 fcd0
tgtpath 36 0/3/1/0.0x207000c0ffd8bee1 fcd0.0x207000c0ffd8bee1
lunpath 1145 0/3/1/0.0x207000c0ffd8bee1.0x0 fcd0.0x207000c0ffd8bee1.0x0
lunpath 1146 0/3/1/0.0x207000c0ffd8bee1.0x401d00000000000
fcd0.0x207000c0ffd8bee1.0x401d00000000000
ctl 4 64000/0xfa00/0x1 N/A
disk 4175 64000/0xfa00/0x36a N/A
The target path and lunpath objects cannot have the hwp_abs_alias attribute assigned after their
HBA has had an absolute alias assigned. This is due to the distributive nature of an absolute alias.
Because the hardware path of the HBA (0/3/1/0) is aliased as fcd0, the target path and lunpath
objects also share that hardware path; you cannot assign an absolute alias to them. You can assign
the hwp_comp_alias attribute for these objects. For example, the following scsimgr command sets
the hwp_comp_alias for the target path (the hardware path alias may now be used as the
identifier) that you can see in the ioscan command:
# scsimgr save_attr –H fcd0.0x207000c0ffd8bee1 –a hwp_comp_alias=MSA_36
# ioscan –P alias_path
Class I H/W Path alias_path
==============================================================
fc 0 0/3/1/0 fcd0
tgtpath 36 0/3/1/0.0x207000c0ffd8bee1 fcd0.MSA_36
lunpath 1145 0/3/1/0.0x207000c0ffd8bee1.0x0 fcd0.MSA_36.0x0
lunpath 1146 0/3/1/0.0x207000c0ffd8bee1.0x401d00000000000
fcd0.MSA_36.0x401d00000000000
ctl 4 64000/0xfa00/0x1 N/A
disk 4175 64000/0xfa00/0x36a N/A
You can also set the lunpath hwp_comp_alias attribute as follows:
# scsimgr save_attr –H fcd0.MSA_36.0x401d00000000000 –a hwp_comp_alias=disk_4175
# ioscan –P alias_path
Class I H/W Path alias_path
==============================================================
fc 0 0/3/1/0 fcd0
tgtpath 36 0/3/1/0.0x207000c0ffd8bee1 fcd0.MSA_36
lunpath 1145 0/3/1/0.0x207000c0ffd8bee1.0x0 fcd0.MSA_36.0x0
lunpath 1146 0/3/1/0.0x207000c0ffd8bee1.0x401d00000000000
fcd0.MSA_36.disk_4175
ctl 4 64000/0xfa00/0x1 N/A
disk 4175 64000/0xfa00/0x36a N/A
If you try to set an absolute alias for a target path or lunpath that already has an absolute alias set for
its HBA, the following error message is displayed:
scsimgr: ERROR: Hardware path is already part of an alias
You must clear the absolute alias for the target path before setting the absolute alias for the HBA. To
clear a hardware path alias, set the attribute value to default with the scsimgr save_attr
command. For example: