The Effect of Device Replacement on Agile Device Files

6
LUN path : lunpath11
Class = lunpath
Instance = 11
Hardware path = 0/1/0/0.0x500508b3009097f9.0x4001000000000000
SCSI transport protocol = fibre_channel
State = UNOPEN
Last Open or Close state = AUTH_FAILED
LUN path : lunpath12
Class = lunpath
Instance = 12
Hardware path = 0/1/0/0.0x500508b3009097f1.0x4001000000000000
SCSI transport protocol = fibre_channel
State = UNOPEN
Last Open or Close state = AUTH_FAILED
Field Replaceable Units
Tape failures often result in FRU replacement. The FRU exchange replaces the target and the LU. A
replaced target has a new Target World Wide Name and a new LU name (WWID).
To minimize the effect of the FRU exchange to the application, devices often spoof the Port World
Wide Name of the replaced target and the WWID of the replaced LU. The following table shows
how FRU exchange and spoofing effects the identifiers:
Target WWN Not
Spoofed
LUN WWID Not
Spoofed
Target WWN Spoofed
LUN WWID Not
Spoofed
Target WWN Not
Spoofed
LUN WWID Spoofed
Target WWN Spoofed
LUN WWID Spoofed
• New lunpath and new
LUN
• New DSF created
• Use
io_redirect_dsf to
redirect I/O from the
old DSF to the new DSF.
• Authentication failure
• N/A
• Run scsimgr
replace_wwid to
authenticate
• New lunpath
• No change to the DSF
• Use rmsf –H
lunpath to clean the
lunpath in the NO_HW
state.
• No change detected
on the host.
Application can
continue to use the
existing DSF.
• N/A
• N/A
This remainder of this section shows the FRU replacement scenarios and their effect on device special
files. Figure 4 shows an original configuration.