HP-UX Encrypted Volume and File System Performance and Tuning

Introduction

HP-UX Encrypted Volume and File System is an OS-based data encryption product. EVFS

transparently encrypts user process data as it is being written to a configured storage device, and

decrypts data that is read from the storage device. Data is encrypted using a symmetric volume

encryption key. The key is loaded into the kernel at volume configuration time and the EVFS kernel

module then uses the key to process outgoing and incoming data for encryption and decryption.

Because of EVFS kernel activity, there is an effect upon the CPU utilization of the system as data

transfer rates increase and decrease, and there is an effect upon system data throughput to and from

the storage device. These effects inspire the question: How does EVFS affect system performance?

The ultimate effect of EVFS upon the user performance experience is directly associated with

application design, file system features, system resources, and tuning. Depending upon these

variables, installing and configuring EVFS and encrypting a data stream may produce no perceived

performance degradation, but it also could noticeably and measurably affect these characteristics.

Therefore, there is no simple response to the question of how EVFS affects system performance. The

only accurate way to profile the performance impact is to install EVFS on a system and run the actual

application through it.

However, utilizing industry defacto benchmarks can provide guidance about how to quantify the CPU

and throughput effects of EVFS. But these metrics can only be a guide, because system variables

contribute significantly to the variation of each test case. Each system and test case will exhibit

unique performance characteristics based upon these variables.