HP Integrity VM Accelerated Virtual I/O Overview

Better Storage Error Reporting
HP-UX 11iv3 SCSI stack provides enhanced error information on IO failures such as media errors and
deferred errors. Host AVIO propagates this information to the guest. For example, when an IO to the
host backing store fails with deferred error, this error is propagated to the guest.
Better Storage Management and Diagnosability
The scsimgr utility in HP-UX 11iv3 Guests provides fine-grained management and tuning capabilities
as well as enhanced diagnostics for storage devices. Refer to scismgr whitepaper and man page for
further details.
AVIO storage has extensive statistics and traces for both the guest and host components. It supports a
unified driver trace mechanism that can be used to trace exception events from both the host and the
guest in a single trace buffer. The events are stored chronologically which is useful to track down
problems at the point in time and the component in the host or guest where the problem originated.
The Integrity VM 4.0 Storage Best Practices section below covers tuning that may be performed on the
host and guest to optimize performance.
Support for LUNs greater than 2 TB in size
Integrity VM 4.0 supports LUNs larger than 2 TB subject to guest OS constraints. While 11iv3 guest
can use the larger LUNs, HP-UX 11iv2 will restrict the usage to 2 TB.
Large Logical Volumes
HP-UX 11iv3 LVM supports a maximum of 256 TB logical volumes, allowing for large logical volumes
to be used as guest disks. Note that the maximum LUN size supported by a guest’s operating system
may be smaller than the maximum logical volume size in the host.
Integrity VM 4.0 Storage Best Practices
This section describes tuning recommendations for storage on Integrity VM 4.0 to provide better
manageability and performance.
HP-UX 11iv3 guests
AVIO storage provides much better throughput with lower CPU utilization for guests with multiple
virtual CPUs. For example, AVIO provides up to 60% throughput improvement with 65% CPU
reduction for 4 KB and 8 KB IOs on a guest configured with 4 virtual CPUs.
It is recommended that customers reconfigure their storage across multiple AVIO storage adapters up
to the number of virtual CPUs in the guest to take advantage of the increased performance. Note that
this reconfiguration of guest HBAs should not impact any guest applications as long as persistent DSFs
are used.
Labeling Raw Disk Backing Stores
The scsimgr utility provides the capability to label disks. Using this feature, Integrity VM administrators
can set device identifiers on raw disk backing stores to to associate host disks with guests.
scsimgr set_devid “disk_label” -D /dev/rdisk/disk49