Question & Answer
Question
I noticed that starting with VIOS 3.1.1, there is meant to be an increased number of NPIVs per FC port i.e. increase from 64 to 255.
"An increased number of NPIVs allowed per Fibre Channel port on the 32 GB Fibre Channel HBA. The current limit is 64, and more NPIVs per port will provide better utilization, density, and efficiency."
I was left wondering if this increase is expected to be available without configuration or not?
Cause
Looking at my VIOS 3.1.1.10 system, lsnports still reported 64 and not 255. However, I'm using 16GB FC adapters not 32GB.
$ ioslevel
3.1.1.10
$ lsnports
name physloc fabric tports aports swwpns awwpns
fcs0 U78C9.001.WZS00BP-P1-C12-T1 1 64 62 3088 3080
fcs1 U78C9.001.WZS00BP-P1-C12-T2 1 64 61 3088 3077
fcs2 U78C9.001.WZS00BP-P1-C6-T1 1 64 64 3088 3086
fcs3 U78C9.001.WZS00BP-P1-C6-T2 1 64 64 3088 3086
In the past, on older VIOS versions, I was aware of an (unsupported) way to increase this value that required us to modify a "hidden" ODM attribute, max_npivs i.e.
$ oem_setup_env
# chdev -l fcs0 -a max_npivs=128-P
fcs0 changed
# exit
$ shutdown -restart
After reboot:
$ lsnports
name physloc fabric tports aports swwpns awwpns
fcs0 U2C4E.001.DBJ8765-P2-C5-T1 1 128 127 2048 2045
fcs1 U2C4E.001.DBJ8765-P2-C5-T2 0 64 64 2048 2048
Answer
In talking with the development support team I was informed that the default max value for max_npivs is still 64, for compliance with older supported HBAs (NPIV capable).
#define DEFAULT_MAX_NPIVS 64
And, when you use 16 Gbps or lesser adapters, the maximum limit of 64 still applies. To enable the new maximum value for a 32Gbps adapter, the below action is required:
$ chdev -dev fcs# -perm -attr max_npivs=255
$ shutdown -restart
This change is supported with 32 Gbps FC adapters. The action above is not dependent on the VIOS level 2.2.6.x or 3.1.x.
Note that there is also a known defect 1074787 LSNPORTS TPORTS VALUE MAY CHANGE UNEXPECTEDLY ON VIOS.
APAR IJ12857 72M (3.1.0.21)
APAR IJ12914 72Q (3.1.1.0)
APAR IJ12861 61r (2.2.6.41)
https://www-01.ibm.com/support/docview.wss?uid=isg1IJ12857
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Modified date:
20 October 2021
UID
ibm15692526