Max Number of EMC LUNs that could be visible on a HPUX Host

[agupt1]

What is the Max Number of EMC LUNs that could be presented to a HPUX Host.

I am presenting the LUNs from the DMX and the HPUX version is 11i v1 and 11i v2.

Also would like to know what is the LUN limit in case the HPUX Hosts are in a MC- Service Guard Cluster

Thanks in advance for the responses.

[Uwe Zessin]

HP-UX uses Volume Set Addressing (VSA) mode. I don't remember exactly how large the LUN address field is - I think it can address up to 16384 LUNs.

You need to tell the storage array to use VSA, too and then the EMC box defines the address limit.

[Stephen Kebbell]

Hi,

just to confirm what Uwe says: VSA must be enabled on the Symmetrix Front-End (FA) Port where you are presenting the Devices.

To check this, run
symcfg -sid list -FA -p -v

Then you will see at the end "Fibre Specific Flags", and a bunch of settings.
Volume_Set_Addressing should be set to Enabled. If it is disabled, you will only be able to address 7 LUNs.
If it needs to be changed, you will have to get in touch with EMC, as you will probably have to unmap all existing devices from that port so you can switch the VSA mode on.

We have over 60 DMX devices mapped to a host (actually an MC/SG Cluster) on one FA-Pair, no problems yet.

Regards,
Stephen

[Uwe Zessin]

Stephen,
does that mean the setting is on the array's front-end port and applies to all attached hosts rather than the DEC/Compaq's style which applies to WWNs (supplied via HSG-connections or EVA-Host entries)?

[agupt1]

Thanks for your reply Guys. We already have VSA set on the Symm FA Ports.

But looking at the Host Connectivity Guide for HPUX, I get the following information

LUNs Per Symm Port : 2048 ( DMX 3)
LUNs Per Server : 16834
LUNS Per HBA :
for HA : 320
for Non HA 512

We already have a MCSG cluster and it has more than 500 devices assigned to it.

Therefore I am trying to make sense out of what is documented and what I see...

Please send in your comments...

Amit

[Duncan Edmonstone]

EMC's data is way out of date here. Look at this whitepaper:

http://docs.hp.com/en/7154/Max_LUN_whitepaper_v11.23.pdf

As you can see the values you are reporting are for 11.00.

Of course in these cases you need to go with something that both HP and EMC support. THe WP above contains the HP acknowledged supported maximums. I'd ask EMC if what they have provided is really their most up-to-date information.

HTH

Duncan

[Stephen Kebbell]

Uwe, to answer your question:
I think you can set the OS on a WWN-per-WWN basis, similar to the SET CONNECTION command on the HSG80. It involves setting the port to heterogeneous mode, too. But I'm not sure what side-effects this could have. I think it would involve being VERY careful when mapping devices to those frond-end ports, so you don't end up with a LUN-Number higher than 7. Our EMC engineer recommended we don't go that route. With VSA Mode set, the Device Mapping function in EMC Control Center automatically recognises this, and increments the vbus and target numbers accordingly when you map devices - so for the 8th device it would set it as vbus=0,target=1,LUN=0

The DMX can have so many frond-end ports that you can separate them on an OS basis. Although in our setup, only HP-UX Hosts are currently usng the DMX

Regards,
Stephen