scsi path change mirroring

[Peter Lachnitt]

Hello all,

I have to change a D330 with a D370 server.
The internal HD's are mirrored to an external
Hass-Tower. Now beginn's my problem, because
the D370 has an another scsi-hw-path for the external devices.
What is the best way to change the path ??
For the data-hd's i want to do:
umount /var/mqm
lvreduce -m 0 /dev/kal/mqm /dev/dsk/c1t15d0
vgreduce /dev/kal /dev/dsk/c1t15d0
Reboot with the new server and tehen
vgextend /dev/kal /dev/dsk/c4t15d0
..
..
But what is the best way for the vg00 ??

Thank's

Peter

[G. Vrijhoeven]

Hi Peter,

Since the hardware differs i would try to create an ignite tape and try to restore it on the D370.If that does not work well go for a clean install.

If the server is installed correct connect the external devices and use vgscan to import those vg's.

HTH,

Gideon

[Robert-Jan Goossens]

Peter,

The best way (if you have a tape device ) is ignite, create a ignite tape and boot/install from tape on the D370.

During the install you can change the VG00 conf in the advanced optins.

Hope this helps,
Robert-Jan

[Florian Heigl (new acc)]

The hardware path is not that relevant in LVM terms.
Create LVM-maps for the external vgs for safety, recover from ignite if possible.
Probably that's it, worst case would be importing via mapfiles.

(*thinking*)
simply do install the new server from ignite, shutdown, connect the HAS and boot up. There should nothing more to be done, I think. (I'm not complete awake, though :)

[Mark Grant]

Actually, as Florian has sort of saying in a tired kind of way :)

Why not just export the volume groups from one machine and import them on the other?

"vgexport -m mapfile -s vgwhatever"

ftp the mapfile to the new machine.

"vgimport -m mapfile -s vgwhatever"

It doesn't matter about the device names or anything.

[Michael Roeder]

Hi,

you could change the HW path, too, if it would make sense. So did i for a SG environment with one external jamaica storage.

Asuming on 1st machine
# ioscan -f | grep -e INTERFACE -e DEVICE | grep -v target | grep ext_bus
Class I H/W Path Driver S/W State H/W Type Description
============================================================================

ext_bus 3 8/8 c720 CLAIMED INTERFACE GSC add-on Fast/Wide SCSI Interface

and on 2nd
haley # ioscan -f | grep -e INTERFACE -e DEVICE | grep -v target | grep ext_bus
Class I H/W Path Driver S/W State H/W Type Description
============================================================================
ext_bus 0 8/8 c720 CLAIMED INTERFACE GSC add-on Fast/Wide SCSI Interface

the device files on machine 1 would be c1t.d.,
on machine 2 c4t.d.

Well, this can be changed with the help of
UXSGKBRC00005958
Title: Changing I/O Instance Numbers On A ServiceGuard Server

The document above also requires this document:
KBRC00004879
Title: How to change the instance numbers of ext_bus and dev files

To change from c1t.d. on machine 1 to c4t.d.,
you could vgexport all c1t.d. devices, change the HW path with
# ioscan -f | grep -e INTERFACE -e DEVICE | grep -v target | awk '{print $3, $1, $2}' > /newcfg

change (assuming the card is in slot 8/8)
8/8 ext_bus 1
to
8/8 ext_bus 4

do a
# init 1
# /sbin/ioinit -f /newcfg -r
The machine would reboot now.
Check the /etc/lvmtab.

Then you have to vgimport on c4t.d. all your disks from c1t.d. .
That should be the state on the D330 you would have on the D370, too.

But do a backup (full ignite) before, it is a potential risk.
You would need about 1/2 h for exporting, changing, rebooting and importing.

After that, you could shutdown the machine again, switch all of the disks in the correct configured slots on machine 2 (SCSI ID's must be the same for the adequate slot).

But, as i told before, think about the need of the same path's, it is more cosmetic.

But if nothing goes wrong, there wouldn't be any need to use the ignite.

A second possibility:
Try if your machine boots without the internal (boot) disks (bo alt).
Break (reduce) the mirror, vgexport the unneeded disk.
(Or simulate an error, draw the internal disks and boot them on the D370.
Let SAM vgimport on D370 this disk (specify options and mound directories). Do so for all disks (without mirror).
You would get 2 Machines with one set of disks, on D330 without mirror or with failed mirrors.
Reboot D370 when done.
Recreate mirrors after reboot (put further disks in). You can get a script for mirroring all of the disks automatically from me, but it will run some hours, depending on the size.

I hope i didn't forget anything

[Michael Roeder]

Correction for your config (i posted the output of my machine)

# ioscan -f | grep -e INTERFACE -e DEVICE | grep -v target | grep ext_bus
Class I H/W Path Driver S/W State H/W Type Description
============================================================================

ext_bus 1 8/8 c720 CLAIMED INTERFACE GSC add-on Fast/Wide SCSI Interface

and on 2nd
haley # ioscan -f | grep -e INTERFACE -e DEVICE | grep -v target | grep ext_bus
Class I H/W Path Driver S/W State H/W Type Description
============================================================================
ext_bus 4 8/8 c720 CLAIMED INTERFACE GSC add-on Fast/Wide SCSI Interface

the device files on machine 1 would be c1t.d.,
on machine 2 c4t.d