HP-UX vPars and Integrity VM V6.3 Administrator Guide

• All the VSP storage available for use by a vPar or VM guest must meet support requirements
for the Integrity server and OS version that comprises the VSP. If the physical storage is not
supported by the VSP, it is not supported for use by a vPar or VM guest.
• All the VSP storage available for use by a vPar or VM guest must be connected with a supported
adapter and driver type. For more information about the list of supported types, see the HP-UX
vPars and Integrity VM Release Notes at http://www.hp.com/go/hpux-hpvm-docs.
If the physical storage is not connected with one of the supported adapter and driver types,
it cannot be used by a vPar or VM guest. Use the ioscan command to display the VSP storage
that is connected to adapters and drivers.
• Any VSP attachable device available for use by a vPar or VM guest must be supported by the
guest OS to which it is attached. If the physical device is not supported by the guest OS, the
device cannot be attached to the vPar or VM guest.
6.4.1.2 Storage performance
To meet the performance requirements of applications running in vPars and VM guests, consider
the potential performance of each type of storage device.
Different types of virtual media have different effects on the performance of the virtual device
because they communicate differently with the VSP to complete vPar or VM guest I/O operations.
To understand the effect of the virtual device type on potential performance, consider the vPar and
VM guest storage I/O stack illustrated in Figure 6 (page 67).
Figure 6 Storage I/O stack
Physical Media
Physical Adapter
Disk Drivers Layer Integrity VM Driver Passthrough layer Virtual Disk
Logical Volume Manager Layer
File Systems Layer
Virtual Lv Disk
Physical Media
Physical Adapter
HP-UX Interface DriverHP-UX Interface Driver
Physical Media
Physical Adapter
NPIV
Virtual File Disk
Attached Devices
HP-UX Interface Driver
VSP Driver Services
For a virtual I/O operation to be completed, the I/O has to travel round trip between the virtual
storage adapter and the VSP physical storage device. The longer the path is, the longer it takes
for virtual I/O to be completed. As shown in Figure 6 (page 67), a virtual I/O operation must
traverse each software layer in order, from where it originates to the physical media. For example,
a virtual I/O operation for a Virtual FileDisk must traverse any logical volume managers the file
system is on and the disk drivers that control the whole disk. Therefore, in general, the higher the
virtual media is in the VSP I/O stack, the slower it operates.
The simplified I/O stack in Figure 6 (page 67) does not completely illustrate all the choices that
can affect the performance.
6.4 Configuring vPar and VM guest storage 67