qeth group devices

6.10 LPAR mode z/VM guest

The qeth device driver requires three I/O subchannels for each HiperSockets CHPID or OSA-Express CHPID in QDIO mode. One subchannel is for control reads, one for control writes, and the third is for data.

The qeth device driver uses the QDIO protocol to communicate with the HiperSockets and OSA-Express adapter (see Figure 1).

Figure 1. I/O subchannel interface
This graphic is described in the surrounding text.
The three device bus-IDs that correspond to the subchannel triplet are grouped as one qeth group device. The following rules apply for the device bus-IDs:
read
no specific rules.
write
must be the device bus-ID of the read subchannel plus one.
data
can be any free device bus-ID on the same CHPID.

You can configure different triplets of device bus-IDs on the same CHPID differently. For example, if you have two triplets on the same CHPID they can have different attribute values for priority queueing.