topic Re: Alternate Paths in Operating System - HP-UX

Alternate Paths

Steve Massey_1 — Mon, 15 May 2000 13:14:07 GMT

I currently have and VG on 1 H/W path.
I want to add a additional alternate H/W path for redundancy.
Has anyone done this or have advice to offer

Thanks

Steve

Re: Alternate Paths

Navied Yousuf — Mon, 15 May 2000 14:21:55 GMT

Greetings,

You can use vgextend to create an alternate link. syntax is as follows.

#vgextend volume-group-name physical-volume-name

First you must find the alternate path for the physical volume already defined in your volume group via a primary path.
#vgextend /dev/vgxx /dev/dsk/cxtydz
where cxtydz refers to alternate path.
CAUTION: DON'T pvcreate the disk via alternate path, because you have already done via primary path.
NY

Re: Alternate Paths

CHRIS_ANORUO — Mon, 15 May 2000 14:43:28 GMT

Hello,

You can do that before ISL prompt.

Re: Alternate Paths

Steve White_1 — Mon, 15 May 2000 14:55:40 GMT

It is no problem to connect 2 SCSI controllers to provide an alternate path. You have to be careful with the controller's address, if they are on one continuous bus you will have to change the SCSI id on the second controller.

I would want the second controller to have the SCSI id = 6

Re: Alternate Paths

Dave Wherry — Tue, 16 May 2000 18:30:24 GMT

Do you have devices that are dual ported? You can't do alternate links with all disk devices. Typically you need some sort of array. You can't do it for internal disks or Jamaicas.
If you have a dual ported device and all the cables are connected, you can find the alternates using ioscan and then simply use vgextend to add them. They will automatically become alternates. Nothing special to do. Just check the vgextend man page.

Re: Alternate Paths

David Meidam — Tue, 16 May 2000 20:41:18 GMT

All the responses are right on. Assuming that you are on a jamaica, FCxx, xp, etc. alternate links are fine. You could also specify them alternate path in a vgcreate. The first device file you specify is the primary and the second device file becomes the alternate.

Re: Alternate Paths

Carlos Fernandez Riera — Wed, 17 May 2000 07:28:59 GMT

When we share to scsi cards between two boxes, Hp?s engenier uninstall internal resistors of both cards,and sets diferent SCSI ids to 7 and 6, because it is same bus.
you should install auto terminated cables too.