Hardware paths changed when the SAN switches are changed.

[Thayanidhi]

Hi,
Three hp-ux servers were connected to IBM SAN (ESS) through single IBM SAN switch(model: 2109/F16). Now SAN Admin want to replace the switch with dual switch for redundancy. After connecting the switches, all the hardware path to SAN disks are changed and new device files are created,
Resulting the VG did not activate. SAN Admin claims there is no configuration
in the switch and are identical/transparent. I also tried to connect the
new switch as it was in the old switch (single switch config, with same cables connected to same port), but still the hardware paths different. Now the only way to bring back the VG is, vgexport and vgimport. Is there any special procedure to replace SAN switch in hp-ux environment? Is hp-ux to be reconfigured whenever the SAN switch is replaced? See eg. below
The old hardware paths were: 1/0/2/0/0.1.16.0.36.0.0
The new hardware path is: 1/0/2/0/0.1.0.0.36.0.0
The fifth octect from right is changed. I believe it is port number where the IBM
ESS connected to. If I change the cable the path also changes.
Both switch configuration is same. But the old switch port was 16,17,18,19.
In the new switches it is port number (i.e. 0 -15).
I connected back to old switch in the same old way.
Can some one explain this number changes eventhough same model
switch is installed?

Thanks in advance.

T.Thayanidh

[Eugeny Brychkov]

If it would be brocade (or OEMed brocade) switch I would say that you're replacing 1GB switch with 2GB one. 1GB switch is having its ports coded as 0x10+port # (thus port 0 is 16 decimal) but 2GB switch has port coded = port # (thus port 0 is 0 decimal). You can not replace brocade 1GB switch with 2GB without path/device file change. If you do replace, then vgexport VGs with map files first, and after change vgimport them.
The general procedure when doing such work is to:
1. check if replacement is applicable - if new switch or topology can substitute old. If not, then develop additional procedures to recover after replacement;
2. configure NEW switch FIRST and only then connect it to the SAN
Eugeny

[Thayanidhi]

Hi,

Both old/new switches are identical. even the firmware level is same.
Why the hardware path show as 16+port# in the old switch,
Port# in the new switch.

Thanks in Advance.

TT

[Eugeny Brychkov]

Then something in configuration is different. Get into switches and compare configurations
Eugeny

[Thayanidhi]

Hi Eugeny Brychkov,

Both switches having same configuration 100%, Except wwn nombers.
I never configured any wwn numbers in hp-ux.

Thanks in Advance

T.Thayanidhi

[Eugeny Brychkov]

I do not know this switch, but here's one more idea - if this switch is expandable (there's possibility to connect some of these switches and form one switch with, let's say, 64 ports) then this switch may have dip switch or again setting which sets switch port numbers range (0-15, 16-31, etc)
Eugeny

[Thayanidhi]

That's one valid point! Let me check up with IBM engineer.

Thanks in advance

TT

[Peter Mattei · Accepted solution]

Well, your 2109 F16 is a Brocade 3800 2Gbit switch. HP sells it as HP SAN switch 2/16.
Find the IBM install guide on ftp://service.boulder.ibm.com/storage/san/2109f16/2109-F16_Installation_Service.pdf

>> You do have a difference in your two switches: Your new switch has the Core PID parm set!
This will change the addressing format! Therefore your area_id changed from 16 to 0.

You just need to set the Core PID to 0.

Find some mor info in the attached doc.

Cheers
Peter

[Thayanidhi]

Hi Peter,

Your attachement look like corrupted, Can you please tell me how to set the
core PID in the SAN Switch (IBM-2109-F16)

Thanks in Advance

T.Thayanidhi

[Eugeny Brychkov]

At the switch FOS prompt type 'configure' command, then answer 'yes' for 'fabric parameters' and press enter key until will see 'Core Switch PID Format:'. Change this value
Eugeny

[Ron Singler]

I have migrated some HP-UX boxes before and we had ensure that the domains from the old switch to the new switch we the same. We also plugged the systems into the exact same blade and port # on the new switch. We did not have to change the VGs in anyway by doing this.