HP-UX 11.31 restore to a new machine - WWN /dev/dsk/diskXXX behavior?

[aeronet]

Hi,

I have a brief question to a restore procedure of an HP-UX 11.31 machine with Fibre Channel disks and LVM.

Scenario:
1. The production machine crashs e.g. hardware failure etc...
2. A new machine delivered to the customer with a new FC HBA
3. I've restored the data of the crashed machine from backup

The question is:
Will be the /dev/dsk/diskXXX device names the same as before on the new machine because of the assigned volume groups / devices?

[Vivek_Pendse · Accepted solution]

Hi,

The device names depends upon the servers hw path, san sw domain id & storage ports.
If you have received the new server with the same cards inserted in the same as of old server, then every thing will be OK.
Secondly, you need to re-direct the LUNs on new WWNs of new server.
Although, you can restore ignite backup & further you can import vgs on new device files & mount the file systems.

Thanks,
Vivek

[aeronet]

Hi Vivek,

though, to the best of my knowledge, the multipath diskXXX device files are assigned with the UUID of the FC VDISK (EVA) and I think this diskXXX device files remain the same even with a new FC HBA.

Am I right about this?

Thanks in advance.

Andre

[Vivek_Pendse]

UUID for disk will not change, but the device file may changed. As you are swapping the server (not the lun from different SAN). As, the difference will come in ioscan o/p & lvmtab o/p.
So, you can use:
1. vgimport with map files by exporting vgs first.
or
2. # scsimgr replace_wwid â D /dev/rdisk/disk
3. # io_redirect_dsf -d /dev/disk/disk -n /dev/disk/disk

Hope, this help you.

Thanks,
Vivek

[Michael Leu]

As far as I know, in 11.31 the mapping from WWID/UUID to /dev/disk/diskXXX is stored in the kernel registry.

So a restore of the same OS image from Ignite to a new hardware _should_ keep the /dev/disk/diskXXX the same. Never tried this myself tho...

If you have to reinstall the OS from scratch, you can use ioinit(1M) to change the instance numbers so 'ioscan -P wwid -C disk' matches the previous config.

[Vivek_Pendse]

Hi,

As per 11.31, in persistent dsf, the matching of lun with dsf goes with WWID, physical location, lunpath for fibre channel for running system (not for recovered system on new hardware).

And, if you check ignite-ux admin guide at "Consistency of I/O Addressing":, then "Recovery with other hardware changes" --> all the pdsf will be renewed.

Thanks,
Vivek

[aeronet]

Re,

thank you for all your information.
I'll try to test it with two test machines in the next few days.

Andre