Peter,

Actually we observed this behavior as far back as SLES10 SP3.  We started using 
persistent device names and forgot about it.

The documentation for this is in the release notes.  From the release notes: 

  Installation using Persistent Device names
    If you plan to add additional storage devices to your system after the OS
    installation, we strongly recommend to use persistent device names for all
    storage devices during installation. The installer by default uses the
    kernel device names.

There is additional information in the SLES11 device driver manual on the 
developerworks site.
>From the Device Drivers, Features, and Commands manual
SC34-2595-01

(from page 35)
autodetect
causes the DASD device driver to allocate device names and the
corresponding minor numbers to all DASD devices and set them online
during the boot process. See “DASD naming scheme” on page 31 for the
naming scheme.
The device names are assigned in order of ascending subchannel numbers.
Auto-detection can yield confusing results if you change your I/O
configuration and reboot, or if you are running as a guest operating system
in VM because the devices might appear with different names and minor
numbers after rebooting.

What may have changed is how dasd= is specified and/or how it works.  It is 
different between the SLES10 and SLES11 manuals.

Ron Foster




________________________________________
From: Linux on 390 Port [LINUX-390@VM.MARIST.EDU] On Behalf Of Peter E. Abresch 
Jr.   - at Pepco [peabre...@pepco.com]
Sent: Thursday, September 29, 2011 9:59 AM
To: LINUX-390@VM.MARIST.EDU
Subject: DASD assignment different between SLES10 and SLES11

Under SLES10, we see the following:

0.0.0150(ECKD) at ( 94:  0) is dasda      : active at blocksize 4096,
600840 blocks, 2347 MB
0.0.0151(ECKD) at ( 94:  4) is dasdb      : active at blocksize 4096,
600840 blocks, 2347 MB
0.0.0152(ECKD) at ( 94:  8) is dasdc      : active at blocksize 4096,
600840 blocks, 2347 MB
0.0.0153(ECKD) at ( 94: 12) is dasdd      : active at blocksize 4096,
600840 blocks, 2347 MB
0.0.0154(ECKD) at ( 94: 16) is dasde      : active at blocksize 4096,
600840 blocks, 2347 MB
0.0.015f(ECKD) at ( 94: 60) is dasdp      : active at blocksize 4096,
150840 blocks, 589 MB

Notice that 0.0.015f is dasdp


Under SLES11, we see the following:

Bus-ID     Status      Name      Device  Type  BlkSz  Size      Blocks
==============================================================================
0.0.0150   active      dasda     94:0    ECKD  4096   2347MB    600840
0.0.0151   active      dasdb     94:4    ECKD  4096   2347MB    600840
0.0.0152   active      dasdc     94:8    ECKD  4096   2347MB    600840
0.0.0155   active      dasdd     94:12   ECKD  4096   2347MB    600840
0.0.0156   active      dasde     94:16   ECKD  4096   2347MB    600840
0.0.015f   active      dasdf     94:20   ECKD  4096   589MB     150840

Notice that 0.0.015f is dasdf rather than dasdp. How can I insure that
0.0.015f is always dasdp?

I read that this behavior had change but naturally now that I need this
doc, I cannot find it anywhere. I do not remember where I read it. Errrr.

Can anyone point me in the right direction? Thanks as always.

Peter

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