New FC adapter port queue depth tuning
cggibbo 270000TMUJ Comments (4) Visits (13678)
# fcstat –D fcs0
FIBRE CHANNEL STATISTICS REPORT: fcs0
FC SCSI Adapter Driver Queue Statistics
Number of active commands: 0
High water mark of active commands: 17
Number of pending commands: 0
High water mark of pending commands: 1
Number of commands in the Adapter Driver Held off queue: 0
High water mark of number of commands in the Adapter Driver Held off queue: 0
The –D is a new option on fcstat, not yet documented in the man pages.
Set num_cmd_elems to >= high water mark of active commands or the default, whichever is greater.
# chdev –l fcs0 –a num_cmd_elems=4096 –a max_
; requires a reboot
Thanks to Dan Braden (IBM ATS) for this tip.