Understanding where DASD configuration resides

Actually, I had wrote that article before a long time ago even before I opened that blog, And after series of extensive improvements I’m glad to publish it.
This article was wrriten in order to clarify how to manage dasd devices on SUSE zLinux SLES  on its many releases..

SUSE configuration locations:

  • Configured via parameters line in /etc/zipl.conf

Kernel parameter line “dasd=…” option.
parameters = “root=/dev/disk/by-path/ccw-0.0.322b-part1 dasd=322b,322f TERM=dumb”
– Requires that you run “zipl” after making changes to /etc/zipl.conf

  • Every Dasd device represented by corresponding configuration file

/etc/sysconfig/hwcfg-dasd-bus-ccw-0.0.*
– Example:

/etc/sysconfig/hardware/hwcfg-dasd-bus-ccw-0.0.0200

Example of configuring new dasd with 0200 device number

format the dasd from zVM:

cpfmtxa 0200 as perm

Login as root to the zlinux server and type

#> lscss

you shuold see in the output an Appropriate line with 0200 device number and you will see that this device is not online.

now we would like to bring that device online with

#> dasd_configure 0.0.200 1

or

#> chccwdev -e 0.0.200

Check that disk is using the DIAG module for access:

#> lsdasd
0.0.0201(ECKD) at ( 94:  0) is dasda      : active at blocksize 4096, 601020
blocks, 2347 MB
0.0.0200(DIAG) at ( 94:  4) is dasdb      : active at blocksize 512, 2048000
blocks, 1000 MB

Now, what’s left is to format it from linux

dasdfmt -b 4096 -y -f /dev/dasdb

then edit /etc/zipl.conf 

parameters = "root=/dev/dasda dasd=100-101,300-301,102-103,200 TERM=dumb"

*What is DIAG (or diagnose instruction)
The diagnose instruction is what some other platforms refer to as “hipervisor call”
so it allows the virtual mchine to request some service from the hipervisor.
One such diagnose instruction that z/VM implements is for high-level disk I/O

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Posted in z/VM, zlinux

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