Abstract; Introduction; Raid Levels; Benchmark Description - Adaptec AHA-3985 Configurations

Abstract

This report summarizes the results of a performance comparison between Novell NetWare's
embedded volume mirroring configuration and Adaptec's AHA-3985 PCI RAID adapter. The
AHA-3985 provides performance and recovery time improvements through advanced fault-
tolerance functionality in a typical NetWare installation as measured by Ziff-Davis'
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NetBench version 3.01.

Introduction

In today's information intensive decision making process, information accuracy and
accessibility is essential. The failure of a file server, even temporarily, can critically impede
the successful operations of an organization. The solution to the availability problem is RAID
(Redundant Array of Inexpensive Disks). RAID employs a data redundancy scheme, so that
in the event of a hard disk failure, there is no interruption in data accessibility and no
information is lost. While the benefits of redundantly storing data is readily apparent in the
presence of a failure, system performance and flexibility during non-critical times must also
be considered when selecting a storage subsystem.

RAID Levels

Within every installation of NetWare, LAN administrators have the option of mirroring data
partitions such that in the event a drive fails, there is a complete copy of the data already
online. This is commonly known as RAID level 1 or mirroring. Adaptec's AHA-3985 PCI
RAID adapter fully supports RAID level 1 as well as the more advanced RAID level 5. RAID
5 is the striping of data across an array of drives with redundancy parity data spread across all
drives. It is this parity data that allows the system to reconstruct the data of a down drive
using only the data on the remaining drives. Because the data is striped across a number of
drives, total I/O throughput is improved, giving RAID 5 superior I/O performance.

Benchmark Description

Performance

To measure the performance levels of the different configurations, Ziff-Davis' NetBench
version 3.01 was set up using 20 client machines. The clients were arranged in 4 groups of 5
and connected to the server through a quad-port Ethernet adapter. (A complete listing of
hardware and software used in this benchmark report can be found in Appendix A.) From
NetBench, the Disk Mix test was selected as being representative of a real world situation.
The user's manual describes Disk Mix as ...
A NetBench 3.01 test that provides you with the primary measure of your
server's file I/O performance. The Disk Mix runs a series of tests based on
information gained from profiling actual applications. As a result, the Disk
Mix exercises your file server the way real users do, but much more
intensely.....
ECX Applications Engineering
Adaptec, Inc.
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January 3, 1996
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