alternate paths in LV?

[Greta Blamire]

Is there a way to set up alternate paths in lvm, so that if a controller goes out the disk will automatically go to the next path and the other controller? I looked through all the lv commands but didn't see anything about this.

[Alan Riggs]

If dual paths exist to your disks (verify wth ioscan -fnC disk) then all that is necessary to add the "shadow" path is to extend your volume group to include the second device file.

ex: /dev/dsk/c1t5d0 & /dev/dsk/c4t5d0 are dual paths to the same disk.

vgcreate vg01 /dev/dsk/c1t5d0
vgextend vg01 /dev/dsk/c4t5d0

[CHRIS_ANORUO]

You can also tell LVM switch to a different controller at any time by entering, for example:
pvchange -s /dev/dsk/c4t5d0

[Rick Garland]

If setting up a new VG and wish to add alternate paths (assuming all other conditions have been met, i.e., the ioscan output) then you can do

vgcreate vg01 /dev/dsk/c1t0d0 /dev/dsk/c2t0d0

The disk device entry on the line will be the alternate path.

[Jimmy Rogers]

I just created a VG with a disk that has an alternate path and the alternate path was added by default with no further action by myself. Note, I did this in a hurry using SAM, results may vary from the command line.

[Sanjay_6]

Hi Greta,

The alternate path for a disk is added using vgextend.

vgcreate /dev/vg_name /dev/dsk/cxtydz
vgextend /dev/vg_name/dev/dsk/cXtYdZ

if /dev/dsk/cxtydz and /dev/dsk/cXtYdZ are the same disk but seen by two different path, if you do vgdisplay after the above commands, you can see the alternate link over there,

vgdisplay -v /dev/vg_name

Try this link,

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B2355-90672/B2355-90672_top.html&con=/hpux/onlinedocs/B2355-90672/00/00/33-con.html&toc=/hpux/onlinedocs/B2355-90672/00/00/33-toc.html&searchterms=link%7calternate&queryid=20020226-105601

Look at "Setting up alternate cables to a physical volume"

Hope this helps.

Regds