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In VIOS, a virtual SCSI server adapter is recognized as a vhostX device:
8.2.2. VIOS configuration and HMC enhancements
No additional configuration in the IBM i client partition is necessary. In VIOS, however, a new
object must be created for each open storage LUN that will be virtualized to IBM i: a virtual
target SCSI device, or vtscsiX. A vtscsiX device makes a storage object in VIOS available to IBM
i as a standard DDxxx disk unit. There are three types of VIOS storage objects that can be
virtualized to IBM i:
•
Physical disk units or volumes (hdiskX), which are open storage LUNs in this case
•
Logical volumes (hdX and other)
•
Files in a directory
For both simplicity and performance reasons, it is recommended to virtualize open storage
LUNs to IBM i directly as physical devices (hdiskX), and not through the use of logical
volumes or files. (See section 9.2 for a detailed performance discussion.) A vtscsiX device links
a LUN available in VIOS (hdiskX) to a specific virtual SCSI adapter (vhostX). In turn, the virtual
SCSI adapter in VIOS is already connected to a client SCSI adapter in the IBM i client partition.
Thus, the hdiskX LUN is made available to IBM i through a vtscsiX device. What IBM i storage
management recognizes as a DDxxx disk unit is not the open storage LUN itself, but the
corresponding vtscsiX device. The vtscsiX device correctly reports the parameters of the LUN,
such as size, to the virtual storage code in IBM i, which in turn passes them on to storage
management.
Multiple vtscsiX devices, corresponding to multiple open storage LUNs, can be linked to a single
vhostX virtual SCSI server adapter and made available to IBM i. Up to 16 LUNs can be
virtualized to IBM i through a single virtual SCSI connection. Each LUN typically uses multiple
physical disk arms in the open storage subsystem. If more than 16 LUNs are required in an IBM i
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