The Effect of Device Replacement on Agile Device Files

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Verifying if spoofing is supported
If spoofing is not supported, the host sees an increase in the number of target paths and lunpaths. You
can use the following command to print the number of target path and lunpath counts, and to
compare the count before and after the FRU is replaced:
1131 :/> scsimgr -p get_attr -a tp_cnt -a lpt_cnt all_ctlr
Effect of io_redirect_dsf or replace_wwid on pass-thru dsf
The scsimgr replace_wwid argument frees the existing minor number associated with the device
and assigns a new minor number. If pass-thru device files are configured, they continue to be
associated with the old minor number. At a later time when a new device is discovered, the freed up
minor number might be assigned to a new device and the pass-thru device files will point to a device
that might not be what the administrator expects. In this case, you must remove any pass-thru device
file.
Glossary
FRU
Field Replaceable Unit
Logical Unit (LU)
A configurable storage volume that processes and responds to SCSI commands. LU is represented by
a device special file on the host operating system.
LUN
A 64-bit identifier of the Logical Unit.
Spoofing
The ability to retain the original target WWN or LU WWID when a device is replaced.