Best Practices for Integrity Virtual Machines

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Flexibility vs. Performance
The various mass storage options for Virtual Machines each have a unique set of benefits. Virtual
hard disks using files on the VM Host provides flexibility in sharing physical storage and the
convenience of managing files on a UNIX system. Mapping a virtual hard drive directly to an entire
physical disk (or LUN) provides the best performance, eliminating the overhead of moving I/O
transactions through the volume management subsystem and/or file system on the VM Host. Logical
volumes, as virtual hard disks, do offer better sharing than physical disks and better performance than
files. Partitions (created with idisk) perform almost as well as disks, but are difficult to use. Figure
4 illustrates the general tradeoffs between the various storage options.
Figure 4 – Defining virtual hard disks using files, logical volumes, or physical disks
present tradeoffs in convenience and performance
File
Logical
Volume
Disk
or LUN
Performance
Convenience and Sharing
File
Logical
Volume
Disk
or LUN
Performance
Convenience and Sharing
File
Logical
Volume
Disk
or LUN
Performance
Convenience and Sharing