Example of a DASD configuration

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To see the device nodes of the prepared DASDs on the host, enter:
# lsdasd
Bus-ID     Status      Name      Device  Type  BlkSz  Size      Blocks
==============================================================================
0.0.7500   active      dasda     94:0    ECKD  4096   7043MB    1803060
0.0.7600   active      dasdb     94:4    ECKD  4096   7043MB    1803060
The udev-created by-path device node for device 0.0.7500 is /dev/disk/by-path/ccw-0.0.7500.
Define the devices:
<disk type="block" device="disk">
    <driver name="qemu" type="raw" cache="none" io="native" iothread="1"/>
    <source dev="/dev/disk/by-path/ccw-0.0.7500"/>
    <target dev="vda" bus="virtio"/>
    <address type="ccw" cssid="0xfe" ssid="0x0" devno="0x7500"/>
</disk>
<disk type="block" device="disk">
    <driver name="qemu" type="raw" cache="none" io="native" iothread="2"/>
    <source dev="/dev/disk/by-path/ccw-0.0.7600"/>
    <target dev="vdb" bus="virtio"/>
    <address type="ccw" cssid="0xfe" ssid="0x0" devno="0x7600"/>
</disk>

This example follows the policy to assign the host device number to the virtual server.

The virtual server sees the standard device nodes, which are of the form /dev/vd<x>, where <x> represents one or more letters. The mapping between a name and a certain device is not persistent across guest reboots. To see the current mapping between the standard device nodes and the udev-created by-path device nodes, enter:
[root@guest:] # ls /dev/disk/by-path -l
total 0
lrwxrwxrwx 1 root root  9 May 15:20 ccw-0.0.7500 -> ../../vda
lrwxrwxrwx 1 root root 10 May 17:09 ccw-0.0.7600 -> ../../vdb
The virtual server always sees the control unit type 3832. The control unit model indicates the device type, where 02 is a block device:
[root@guest:] # lscss
Device   Subchan.  DevType CU Type Use  PIM PAM POM  CHPIDs
----------------------------------------------------------------------
0.0.7500 0.0.0000  0000/00 3832/02 yes  80  80  ff   00000000 00000000
0.0.7600 0.0.0001  0000/00 3832/02 yes  80  80  ff   00000000 00000000