topic Re: Disk hardware address to device name mapping problem in Operating System - HP-UX

Disk hardware address to device name mapping problem

Shyam Moghe — Wed, 10 Mar 2010 15:33:35 GMT

Hi,

I would like to know if there is any way on HPUX IA 11.31 to initialize disks in expected order.

Problem details:
----------------
Here "0/6/0/0/0/0/4/0/0/0.0.0" is local disk, "255/1/0.0.0" is DVD-ROM and rest of the disks are san luns.

Currently the system is booted over ignite server for restore. In this restore environment I am seeing "255/1/0.0.0" is initialized with device /dev/dsk/c2t0d0 and san disk "0/7/0/0/0/0.22.1.255.0.0.0" with /dev/dsk/c1t0d0 device.
But when this client was up and running with full OS these mapping was exact reverse. Basically DVD "255/1/0.0.0" was getting initialized before san luns and it had device file /dev/dsk/c1t0d0 associated with it.

In restore environment, if I use mksf to forcefully initialize device for required HW address, then "ioscan -fnC disk" shows mapping correctly. But if I do "insf -eC disk", it again re-initializes with the wrong mapping.

Is there any way to restrict this mapping so that "insf -e" will not change it.

# ioscan -fnC disk
Class I H/W Path Driver S/W State H/W Type Description
=====================================================================
disk 0 0/6/0/0/0/0/4/0/0/0.0.0 sdisk CLAIMED DEVICE HP LOGICAL VOLUME
/dev/dsk/c0t0d0 /dev/rdsk/c0t0d0
/dev/dsk/c0t0d0s1 /dev/rdsk/c0t0d0s1
/dev/dsk/c0t0d0s2 /dev/rdsk/c0t0d0s2
/dev/dsk/c0t0d0s3 /dev/rdsk/c0t0d0s3
disk 1 0/7/0/0/0/0.22.1.255.0.0.0 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c1t0d0 /dev/rdsk/c1t0d0
disk 2 0/7/0/0/0/0.22.1.255.0.0.1 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c1t0d1 /dev/rdsk/c1t0d1
disk 3 0/7/0/0/0/0.22.1.255.0.0.2 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c1t0d2 /dev/rdsk/c1t0d2
disk 4 0/7/0/0/0/0.22.1.255.0.0.3 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c1t0d3 /dev/rdsk/c1t0d3
disk 5 0/7/0/0/0/0.22.1.255.0.0.4 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c1t0d4 /dev/rdsk/c1t0d4
disk 6 0/7/0/0/0/0.22.1.255.0.0.5 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c1t0d5 /dev/rdsk/c1t0d5
disk 7 0/7/0/0/0/0.22.1.255.0.0.6 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c1t0d6 /dev/rdsk/c1t0d6
disk 8 0/7/0/0/0/0.22.1.255.0.0.7 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c1t0d7 /dev/rdsk/c1t0d7
disk 20 255/1/0.0.0 sdisk CLAIMED DEVICE TEAC DVD-ROM DW-224EV
/dev/dsk/c2t0d0 /dev/rdsk/c2t0d0

Thanks.

Re: Disk hardware address to device name mapping problem

Torsten. — Wed, 10 Mar 2010 19:08:09 GMT

I assume in your first installation you added the SAN disks later, now they are present, hence you get this order.
Any problems with this?

BTW; why is your array loop connected?

Re: Disk hardware address to device name mapping problem

Shyam Moghe — Thu, 11 Mar 2010 06:10:40 GMT

I assume in your first installation you added the SAN disks later, now they are present, hence you get this order.
Any problems with this?
Yes, the SAN disks added later. But why did the DVD drive is not getting initialized before SAN disks. DVD drive is getting initialized with c2t0d0 instead of c1t0d0. And working client was giving c1t0d0 for DVD drive and other for SAN.
We need correct ordering as we do map original client device names to the one available in our restore environment. In this case mapping is failing because of reverse initialization.
Any idea?

BTW; why is your array loop connected?
I really did not get this question. Please can you clarify?

Thanks.

Re: Disk hardware address to device name mapping problem

Torsten. — Thu, 11 Mar 2010 06:18:43 GMT

The hardware path always decides - it is in numeric order, e.g.

1/...
2/...
...
255/...

Re: Disk hardware address to device name mapping problem

Shyam Moghe — Thu, 11 Mar 2010 10:20:12 GMT

But on original client it was like below.

Class I H/W Path Driver S/W State H/W Type Description
=====================================================================
disk 0 0/6/0/0/0/0/4/0/0/0.0.0 sdisk CLAIMED DEVICE HP LOGICAL VOLUME
/dev/dsk/c0t0d0 /dev/dsk/c0t0d0s2 /dev/rdsk/c0t0d0 /dev/rdsk/c0t0d0s2
/dev/dsk/c0t0d0s1 /dev/dsk/c0t0d0s3 /dev/rdsk/c0t0d0s1 /dev/rdsk/c0t0d0s3
disk 4 0/7/0/0/0/0.22.0.255.0.0.0 sdisk CLAIMED DEVICE DGC LUNZ
/dev/dsk/c2t0d0 /dev/rdsk/c2t0d0
disk 5 0/7/0/0/0/0.22.1.255.0.0.0 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c3t0d0 /dev/rdsk/c3t0d0
disk 9 0/7/0/0/0/0.22.1.255.0.0.1 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c3t0d1 /dev/rdsk/c3t0d1
disk 10 0/7/0/0/0/0.22.1.255.0.0.2 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c3t0d2 /dev/rdsk/c3t0d2
disk 11 0/7/0/0/0/0.22.1.255.0.0.3 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c3t0d3 /dev/rdsk/c3t0d3
disk 12 0/7/0/0/0/0.22.1.255.0.0.4 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c3t0d4 /dev/rdsk/c3t0d4
disk 13 0/7/0/0/0/0.22.1.255.0.0.5 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c3t0d5 /dev/rdsk/c3t0d5
disk 14 0/7/0/0/0/0.22.1.255.0.0.6 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c3t0d6 /dev/rdsk/c3t0d6
disk 15 0/7/0/0/0/0.22.1.255.0.0.7 sdisk CLAIMED DEVICE DGC RAID 0
/dev/dsk/c3t0d7 /dev/rdsk/c3t0d7
disk 2 255/1/0.0.0 sdisk CLAIMED DEVICE TEAC DVD-ROM DW-224EV
/dev/dsk/c1t0d0 /dev/rdsk/c1t0d0

Re: Disk hardware address to device name mapping problem

Torsten. — Thu, 11 Mar 2010 10:41:50 GMT

Well, the devices came later.

The existing device files will not change!

Still the hardware path decides about the order, example:

1. 1/... - first
2. 3/... - second

now you add something on 2/... - it will become the third.

If you do a new installation, the order will change.

Re: Disk hardware address to device name mapping problem

Shyam Moghe — Thu, 11 Mar 2010 14:14:37 GMT

Yes it is like that.
We removed san luns connection physically and rebooted the machine. "insf -eC disk" has shown the device <-> HW path mapping as original.
DVD 255/1/0.0.0 got device /dev/dsk/c1t0d0.

Then we connected san luns and it got mapped to /dev/dsk/c2t0d?

We are wondering is there any way to change HW <-> device mapping without removing physical connection (like we removed san lun and attached back.)
I know using mksf we can assgin device to hw path but running "insf -eC disk" command changes this back to default. Somehow we want to do persistent HW path to device file mapping.

Re: Disk hardware address to device name mapping problem

Torsten. — Thu, 11 Mar 2010 14:20:42 GMT

You may consider to play around with scsimgr or ioinit, but is it really this important for you? You need to do this every time you restore the system.

Re: Disk hardware address to device name mapping problem

Shyam Moghe — Thu, 11 Mar 2010 14:28:29 GMT

Unfortunately yes. The restore logic is dependent on this mapping.

Re: Disk hardware address to device name mapping problem

Torsten. — Thu, 11 Mar 2010 14:30:32 GMT

What "restore logic"?

For all the disks you should always keep an LVM mapfile, so you can easily do an vgimport to get the original LVM configuration back. In this case the disk device files doesn't matter at all.