Alternate Link - MirrorDisk/UX

[Alzhy]

Thanks thus far to those that have responded. Again, I am sure we've 2 physical disks here - and this is an N-Class (rp7400). What I am not sure though is if the N-Class's 2 internal disks are multi-ported.

I am still wondering whay we have this config - c2t6d0 being marked on the root VG as an alternate link even if ioscan shows c2t6d0 as a separate physical disk.
Any more ideas?

[Mark Greene_1]

In addition to the lvlnboot, try this:

lifls -Cl /dev/dsk/c2t6d0

If that returns something like this:

volume ISL10 data size 7984 directory size 8 99/10/28 15:23:53
filename type start size implement created
===============================================================
ISL -12800 584 240 0 99/10/28 15:23:53
AUTO -12289 824 1 0 99/10/28 15:23:53
HPUX -12928 832 800 0 99/10/28 15:23:53
PAD -12290 1632 1700 0 99/10/28 15:23:54
LABEL BIN 3336 8 0 02/05/28 10:08:10

They the disk has the boot information on it. What might have been done is the disk setup to be a mirror of the primary boot disk, but instead of being activated as a mirror copy, it was setup as an alternate link. Whether by accident or design, I cannot say.

You big issue here is that you cannot see what is on the drive. What you can try, if you've the time and opportunity, is to boot from it if it's been setup to be a boot disk.

Power down your system. Remove the primary boot drive. Power-up the system. Interrupt the boot process and interact with the ISL. Scan for boot paths to confirm that the ISL sees the disk. If so, select that boot path and see if the system comes up. If it does, take a look at what is on the drive, and how old it is.

If that doesn't work, power the system back down, replace the boot drive, and bring it back up. You can then remove the alternage link and use the drive as a mirror disk.

HTH
mark

[Animesh Chakraborty]

"I've 2 N-Classes with 2 18G internal disks, one I did not install, the other I installed and did bootdisk Mirroring using MirrorDisk/UX."

Can you give us the mirroring steps you followed for boot disk mirrioring?

Thanks
Animesh

[Todd McDaniel_1]

All:

Please forgive me for digging up an old post...but I am curious for your answer.

Did you have a second disk or merely an alternate path along a different controller?

[Alzhy]

Subsequent reboots fixed this strange problem.. And yes indeed on this N-Class, the two are distinct physical disks..

I was relatively "RE-Acclimatizing" back then and getting familair with HP-9000 environments. Now that I've almost a year's worth of experience with more current HP OS, software and HW (and getting better at that)... I can deduce (theorize?) the following:

c2t6d0 probably was a DD copy of the primary OS some time back. hence, it was being treated as an alternate link or PV link...


But I could be wrong...

[G. Vrijhoeven]

Hi Nelson,

We once did this deleberately in a lab on a server that had no alternate link just to see if we could get it working. What we did was a dd from one disk to the other.
When you do a pvcreate LVM writes a "unique" number to the disk to id it. When you do a dd from the entire disk to a second disk this id is copied. When you do a vgextend LVM will think it is an alternate link since the numbers match.

HTH,

Gideon

[Alzhy]

Aha! so the theory is correct!
Thanks!