Intergraph Webscale User manual

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Based on technology from Valence™ Research, Inc.

User’s Guide

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Huntsville, AL

WebScale™ User’s Guide

Version 2.1

This document may not be reproduced or transmitted in any form or by any means,

electronic or mechanical, including photocopy, recording, or by any information storage

and retrieval system, without written permission from Intergraph Computer Systems,

Inc.

Specifications are subject to change without notice.

WebScale is a trademark of Intergraph Computer Systems, Inc.

Convoy Cluster and Valence are trademarks of Valence Research, Inc.

Windows NT is a registered trademark of Microsoft Corporation.

Please direct all correspondence to:

Intergraph Computer Systems, Inc.

Huntsville, Alabama 35894-0001

U.S.A.

1-800-345-4856

[email protected]

WELCOME TO WEBSCALE™

Thank you for selecting WebScale™ based on technology from Valence™ Research,

Inc. By clustering two or more Windows NT computers with WebScale, you will

dramatically enhance the availability of your Internet server applications, such as World

Wide Web, proxy, DNS, and FTP servers. At the same time, WebScale can help you to

scale your server’s performance to keep up with the ever-increasing demands of your

Internet-based clients. Best of all, WebScale provides a cost-effective solution that

works with all of your Internet-based services.

This User’s Guide explains what WebScale does and how it works to deliver high

availability and scalability for your Internet server applications. Step-by-step

instructions for installing and using WebScale help you to get your WebScale cluster up

and running quickly and easily. This guide also explains how to obtain technical

support if you have problems.

TABLE OF CONTENTS

WELCOME TO WEBSCALE™I

TABLE OF CONTENTS II

WHAT’S NEW IN VERSION 21

REMOVAL OF SINGLE NIC LIMITATIONS 1

REMOTE CLUSTER CONTROL 2

ENHANCED SESSION SUPPORT 2

PERFORMANCE ENHANCEMENTS 2

INTRODUCTION 4

ADVANTAGES OF USING WEBSCALE 5

OVERVIEW OF WEBSCALE’S SOFTWARE CONFIGURATION 7

DATABASE ACCESS WITHIN LOAD BALANCED SERVER APPLICATIONS 8

INSTALLATION AND CONFIGURATION 9

SYSTEM REQUIREMENTS 9

SINGLE NETWORK INTERFACE CARD LIMITATIONS 10

QUICK START GUIDE FOR WINDOWS NT EXPERTS 10

INSTALLATION 13

SETUP: CONFIGURING WEBSCALE’S PARAMETERS 19

SETTING UP THE WINDOWS NT BINDINGS 35

INSTALLING SOFTWARE UPGRADES 46

DISABLING AND REMOVING WEBSCALE 47

EXECUTION AND CONTROL 49

THEORY OF OPERATION 49

CLUSTER CONTROL 54

ERROR DETECTION AND HANDLING 59

EVENT LOGGING 60

TROUBLESHOOTING GUIDE 64

GLOSSARY OF TERMS 71

INDEX 75

WHAT’S NEW IN VERSION 2

WebScale™ Version 2, has exciting new features that make WebScale easier to install

and use. This version also incorporates several performance enhancements that take full

advantage of the latest, pipelined network drivers and adapter cards and ensure smooth

failover and failback behavior. The key changes are outlined in the following

subsections.

Removal of Single NIC Limitations

By default, WebScale now directs network traffic to the cluster NIC’s using a multicast

cluster MAC address instead of by using a non-multicast cluster MAC address. The

WebScale driver no longer instructs the NIC driver (via the Windows NT Registry) to

load the cluster MAC address into the NIC card at system startup. This has several

important benefits:

•Cluster hosts do not need two NIC cards to allow them to communicate with each

other. One cluster NIC can be used on each cluster host, and both the cluster’s

primary IP address and the dedicated IP address can be bound to this card via

WebScale.

•Cluster hosts now avoid the additional networking overhead associated with the

use of a single NIC card. In previous versions, all cluster hosts would receive

network traffic from outside the cluster that was intended for a particular host.

This overhead is now removed.

•WebScale now works properly with Ethernet switches, which require that all

switch ports have unique MAC addresses.

•WebScale now works with network adapter cards that do not allow their MAC

addresses to be changed. (Only a few, low-end cards have this limitation.)

•WebScale’s internal (one per second) messages now introduce less network

overhead on the subnet since only the cluster hosts receive them. They were

previously broadcast to all hosts.

WebScale automatically handles the resolution of the cluster IP address to its associated

multicast cluster MAC address by the Address Resolution Protocol (ARP). However,

the use of a multicast MAC address may not be supported by the ARP implementation

on some routers. In this case, it is necessary to create a static ARP entry within the

router.

For backward compatibility, WebScale supports non-multicast cluster IP addresses that

were used in previous versions. The WebScale Setup dialog lets you select between

multicast and non-multicast addressing. Starting with version 2.1, you can use a unicast

MAC address with switches.

WebScale™ User’s Guide

Also new with version 2.1, WebScale now automatically generates the cluster MAC

address based on the cluster’s primary IP address. This simplifies installation and lets

you put multiple WebScale clusters on the same subnet without manually changing the

MAC address. When configuring your router, you can use the new webscale

ip2mac command to conveniently list the MAC address used for a given cluster IP

address.

Remote Cluster Control

WebScale’s cluster control program (webscale.exe) has been enhanced to let you start,

stop, and query the cluster from any networked Windows NT system. You can control

all cluster hosts with one command, or you can control them individually. The control

program has full password protection to prevent unauthorized access. When executed

on the cluster hosts, the control program operates in the same manner as it did in

previous versions.

Starting with version 2.1, you can now instruct WebScale to complete all outstanding

connections prior removing a host from the cluster or disabling traffic handling for port

rules using the webscale drainstop and webscale drain <port> commands.

This avoids disrupting service to clients when these cluster set changes need to be made.

Enhanced Session Support

Support for client sessions has been enhanced in version 2. If a server application (such

as a web server) maintains state information about a client session that spans multiple

TCP connections, it is important that all TCP connections for this client be directed to

the same cluster host. In previous versions of WebScale, you could optionally force this

behavior by setting the WebScale registry parameter ScaleSingleClient to 0. Otherwise,

WebScale would load balance TCP connections from a single client across the cluster to

maximize performance. Starting with version 2, you can invoke support for client

sessions, called client affinity, individually for each port range.

In addition, version 2 lets you optionally modify WebScale’s session support to direct

all client requests from a TCP/IP Class C address range to a single cluster host. This

feature ensures that clients which use multiple proxy servers to access the cluster will

have their TCP connections directed to the same cluster host. The use of multiple proxy

servers at the client’s site causes requests from a single client to appear to originate

from different systems. Assuming that all of the client’s proxy servers are located

within the same 256 host Class C address range, you can now ensure that client sessions

are properly handled with minimum impact on load distribution among the cluster hosts.

Performance Enhancements

Version 2 incorporates numerous internal performance enhancements to further

streamline WebScale’s actions and ensure that WebScale takes full advantage of the

WebScale™ User’s Guide

latest NDIS device drivers and NIC hardware. WebScale fully pipelines all packet

reception and transmission to the maximum extent supported by NDIS drivers and

protocol stacks. Also, WebScale’s load balancing mechanisms have been refined to

ensure the smoothest possible load transfers when cluster hosts enter and exit the cluster

and during recovery from subnet conditions.

WebScale™ User’s Guide

INTRODUCTION

WebScale™ Software is an innovative software product that enhances the availability

and scalability of Internet server applications, such as web servers, FTP servers, and

other mission-critical applications. A single Windows NT computer can only provide a

limited level of reliability and scalable performance. However, by combining the

resources of two or more Windows NT computers into a single cluster, WebScale

cluster can deliver the reliability and performance that web servers and other mission

critical applications need. The following diagram depicts a cluster with four host

computers, or servers, within the cluster:

Each host runs a separate copy of the desired server applications, such as web servers,

FTP, telnet, email, etc. For some services, such as web servers, a copy of the

application runs on all hosts within the cluster, and WebScale load-balances the

workload between them. For other services, such as email, only one copy of the service

handles the workload within the cluster. Instead of load balancing these services,

WebScale allows the network traffic to flow to one host, and it moves the traffic to

another host in case of failure.

WebScale clusters together several computers running server applications that use the

TCP/IP networking protocol. WebScale allows all of the machines in the cluster to be

addressed by the same set of cluster IP addresses (while maintaining their existing

addressability using unique, dedicated IP addresses). WebScale distributes incoming

client requests in the form of TCP/IP traffic across the hosts.

To scale server performance WebScale can load-balance the incoming TCP/IP traffic

WebScale™ User’s Guide

across all the hosts in the cluster. In this case, a copy of the server application runs on

all of the load-balanced hosts, and the load is partitioned among the hosts; the load

percentage to be handled by each host can be tailored as necessary. Hosts can be

dynamically added to the cluster as necessary to handle increased load. WebScale can

also direct all traffic to a designated single host, called the default host.

WebScale manages the TCP/IP traffic as necessary to maintain high availability for

server applications. When a host fails or goes offline, WebScale automatically

reconfigures the cluster to direct client requests to the remaining computers. For load-

balanced applications, the load is automatically redistributed among the surviving

computers. Applications with a single server have their traffic redirected to a specific

host. Connections to the failed or offline host are lost. Once the necessary maintenance

is completed, the offline computer can transparently rejoin the cluster and regain its

share of the workload.

Advantages of Using WebScale

WebScale installs as a standard Windows NT networking driver on two or more

Ethernet or FDDI connected computers. Once installed, it operates in a fully

transparent manner to both server applications and to TCP/IP clients worldwide.

WebScale’s simple and elegant approach to clustering server applications lets users

employ off-the-shelf software components, such as existing WWW, FTP, or proxy

servers and other popular Internet applications. WebScale enhances fault-tolerance and

scales performance transparently to the TCP/IP protocol, to server applications, and to

clients.

WebScale gives the user flexible, fine-grained control over its operations. It lets the

system administrator configure load balanced (also called multi-server) and single-

server network traffic handling parameters for individual TCP/UDP ports and for

sequential groups of ports (called port ranges). In addition, individual servers can be

commanded to dynamically (i.e., without re-booting the server) leave and join the

cluster by issuing simple commands. Cluster parameters also can be modified without

bringing down the cluster.

WebScale’s approach to load balancing TCP/IP connections is superior to using a

round-robin domain name server (DNS) because:

•the same server IP addresses are used across the cluster,

•a round-robin DNS does not provide fault tolerance (it blindly directs traffic to

failed servers),

•WebScale’s load balancing has finer granularity (per-client request vs. per-DNS

query from the client),

•each client benefits from WebScale’s load balancing since its requests are

distributed across the cluster,

WebScale™ User’s Guide

•WebScale allows finer control over the load distribution among the servers by

designating load percentages to be assigned for the servers (the next version of

WebScale will provide dynamic load balancing according to the measured server

load).

WebScale’s implementation in software that is distributed across the cluster hosts has

several advantages over the use of centralized, hardware-based solutions for distributing

TCP/IP requests within a cluster. First, it avoids introducing a single point of failure

that can disrupt operations. Second, WebScale’s performance tracks the constantly

improving performance of the systems on which it runs. Hardware-based solutions

have fixed performance limits with limited lifetimes.

WebScale’s fully distributed architecture also has advantages in comparison to other

software solutions, which redirect incoming IP packets to load balance traffic among the

cluster hosts. WebScale imposes significantly less overhead because it does not modify

and retransmit packets. It also can respond faster to system outages and rebalance the

load within a few seconds.

WebScale™ User’s Guide

Overview of WebScale’s Software Configuration

WebScale runs as a Windows NT networking driver and its operations are transparent to

the TCP/IP networking stack. The above diagram shows the relationship between

WebScale and the other software components in a typical configuration of a WebScale

Server:

To ensure maximum network performance, WebScale normally uses a second network

interface card (NIC) to handle cluster traffic, while other network traffic to the server

goes through a separate NIC. However, a second network card is not required.

WebScale™ User’s Guide

Database Access within Load balanced Server Applications

Some server applications access a database that is updated by client requests. When

these applications are load balanced in the cluster, these updates need to be properly

synchronized. Each server can use independent copies of databases residing within

their individual servers, which are merged offline as necessary. Alternatively, the

clustered servers can share access to a separate, networked database server, as shown in

the diagram below. A combination of these approaches can also be used. For example,

web pages can be replicated among all clustered servers to ensure fast access and

complete fault tolerance. However, database requests should be forwarded to a shared

database server to synchronize updates from multiple web servers. Some mission-

critical applications may require the use of highly available database engines to ensure

complete fault tolerance for the service. Over the next five years, clustered database

software will be deployed to deliver highly available and scalable database access

within the cluster.

For more information on how WebScale achieves fault-tolerance and scalability, please

consult the section Theory of Operation.

WebScale™ User’s Guide

INSTALLATION AND CONFIGURATION

To install and fully configure WebScale for use, please follow the instructions in the

following sections for all Windows NT systems that you plan to use in the cluster.

System Requirements Hardware and software requirements for

running WebScale

Quick Start Guide Abbreviated installation instructions for

Windows NT experts

Installation How to obtain and install WebScale on your

Windows NT system

Setup Detailed, step-by-step instructions for setting

WebScale’s parameters

Setting Windows NT

Bindings Detailed, step-by-step instructions for setting

the correct Windows NT bindings

Installing Software

Upgrades How to install upgrades to your WebScale

Disabling and Removing How to temporarily disable or to remove

WebScale

System Requirements

WebScale is designed to work as a standard networking device driver under the

Windows NT 4.0 Server or Workstation operating system. Since WebScale is designed

to provide clustering support for TCP/IP-based server applications, the Windows NT

TCP/IP protocol must be installed in order to take advantage of WebScale’s

functionality. The current version of WebScale operates on FDDI or Ethernet based

local area networks within the cluster. It has been tested on 10 Mbps, 100 Mbps, and

gigabit Ethernet networks with a wide variety of network adapter cards.

WebScale consumes less than 1.2MB of hard-drive space and occupies between 250KB

and 4MB of RAM during operation using the default parameters, depending on the

network load. The parameters can be modified to allow up to 15MB memory to be

used. Typical memory usage ranges between 500KB to 1MB.

For optimum cluster performance, a dedicated network interface card (NIC) should be

installed to handle cluster traffic. In this configuration, one card will carry all of the

usual networking traffic destined to the server as an individual computer on the

network, while the other one will handle the networking traffic addressed to the server

as part of WebScale cluster. If multicast cluster MAC addressing is disabled, it is still

possible to use WebScale with a single NIC in the system, but this will limit overall

performance and networking functionality within the cluster itself; please refer to the

Single network interface card limitations topic for more details.

WebScale™ User’s Guide

If you are using a router to connect your cluster to its clients, be sure that the router has

its proxy ARP support enabled. (This allows the router to map the cluster’s primary IP

address and other multi-homed addresses to the corresponding MAC address.) If your

router does not route to the cluster with proxy ARP support enabled, you also can create

a static ARP entry in the router. Cisco routers require a static ARP entry because they

do not support proxy ARP for multicast MAC addresses.

Single Network Interface Card Limitations

Note: The limitations described in this section apply only when multicast cluster MAC

address support is disabled. Starting with Version 2, a multicast cluster MAC address is

used by default for cluster operations. For backward compatibility with previous

versions, you can disable the use of multicast cluster MAC addressing in the WebScale

Setup dialog. In this case, please carefully read the limitations described below.

If you disable multicast support, you should install a dedicated network interface card

(NIC) to handle cluster traffic in order to achieve optimum performance and the full

range of networking functionality. Although it is possible to have a successful cluster

installation with only one NIC, there are two limitations to this approach:

•Computers within the cluster will not be able to communicate among themselves

with any networking protocol, not just TCP/IP. This can be a special problem if

one or more of the clustered servers also act as primary and backup domain

controllers.

•Networking traffic destined to individual servers within the cluster will generate

additional networking overhead for all machines in the cluster.

These limitations may not be important for many installations. If the computers within

the cluster are only accessed from outside the cluster (i.e., there are no intra-cluster

communications) and non-cluster communications are infrequent (for example short

nightly updates of the web server content to individual computers in the cluster), the use

of a single networking card should be sufficient. Also, it is always possible to test and

demo WebScale using a single network card prior to installing additional cards for

operational purposes.

The topic Setting Up the Windows NT Bindings contains special instructions for

setting up WebScale on computer with a single network interface card. When using a

single NIC, you later can add a second NIC later and follow the instructions in the

subsection for multiple network interface cards.

Quick Start Guide for Windows NT Experts

The following guide lets Windows NT experts quickly install and configure WebScale

for use. This guide assumes that you are familiar with installing network adapter cards

and driver software for Windows NT systems. For more detailed, step-by-step

WebScale™ User’s Guide

instructions, please refer to the Installation section.

Before installing WebScale, be sure to read the section System Requirements.

Have the following items ready:

•The websNNN.exe file that contains the WebScale distribution. This file can be

obtained from Intergraph Computer Systems, Inc. The NNN encodes the version

number of the distribution; for example, webs10b.exe is the Beta release of

WebScale.

•The cluster’s full Internet name that you plan to use, such as, cluster.your-

company.com.

•The IP address that you plan to use for the cluster. This cluster IP address will be

used on all hosts in the cluster.

•The current IP address for each host in the cluster. This dedicated IP address is

unique to each host and is used for network traffic other than that to be serviced

by the cluster as a whole, such as, telnet sessions with individual hosts.

•(Optional) A license key from Intergraph Computer Systems. If you are

installing WebScale for evaluation purposes, no license key is needed.

•(Optional) A second network adapter card to handle the cluster’s network traffic.

You can use your existing adapter cards to run WebScale; please see the section

Single Network Interface Card Limitations. The second adapter is called

cluster adapter, and the host’s original adapter card is called the dedicated

adapter. If you have a single adapter card, it will serve both purposes.

To install and configure WebScale, please follow these steps for each host to be used in

your WebScale cluster:

æIf you are using a router to send network traffic directly to the cluster, be sure that

the router has its “proxy ARP” functionality enabled. See System

Requirements for details.

æIf you are using multiple adapter cards, install the second network adapter card.

æUnpack the WebScale distribution by running websNNN.exe.

æStart the Windows NT Network setup dialog.

æInstall WebScale as a new adapter; use the WebScale distribution files when

prompted for a disk. This will install two networking objects, a WebScale Virtual

NIC adapter and a WebScale Driver protocol.

⇒When installation completes, the WebScale Setup dialog will automatically start.

(You can also run this dialog by highlighting the WebScale Virtual NIC adapter and

clicking on the Properties button.)

WebScale™ User’s Guide

æFill out the requested cluster, host, and licensing information in the dialog and

click on the Apply button to make use of the features enabled by your license key.

æCreate port rules to specify how you want WebScale to handle network traffic for

specific TCP and/or UDP ports. Refer to the Port Rules section for more details.

æClick on the OK button to complete the WebScale Setup dialog.

æSelect the Bindings tab in the Windows NT Network dialog and view the bindings

for all protocols.

æBind the WebScale Driver protocol to the WebScale Virtual NIC adapter and to the

cluster adapter.

æUnbind the WebScale Driver protocol from the dedicated adapter (unless you are

using a single adapter, in which case you should leave the adapter bound).

æBind the TCP/IP protocol and the WINS Client protocol to the WebScale Virtual

NIC adapter.

æBind the TCP/IP protocol and the WINS Client protocol to the dedicated adapter

(unless you are using a single adapter, in which case you should unbind the

adapter).

æUnbind the TCP/IP protocol and the WINS Client protocol from the cluster adapter.

It will already be unbound if you have a single adapter.

æMove the WebScale Virtual NIC adapter below the dedicated adapter in the list of

adapters for the TCP/IP protocol and the WINS Client protocols.

æClose the Network setup dialog.

æRestart the computer.

After installation has been completed on all hosts in the cluster, you can control cluster

operations using the webscale.exe control program, which is described in the

Execution and Control section.

If you should need to disable the WebScale driver after installation:

æUnbind the WebScale Driver from all hardware adapters.

æUnbind the TCP/IP protocol and the WINS Client protocol from the WebScale

Virtual NIC adapter.

æBind the TCP/IP protocol and the WINS Client protocol to the hardware adapters

as desired.

WebScale™ User’s Guide

Installation

WebScale must be installed and configured on every Windows NT computer (called a

host) that will be part of a cluster. Please follow these steps to install WebScale on each

host: