Compaq 179740-001 - ProLiant - 3000 Quick reference guide

WHITEPAPER
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ECG073/0398
[March 1998]
Prepared By
Windows NT
Integration Team
Compaq Computer
Corporation
CONTENTS
Executive Summary 3
PCI Architecture 3
PCI Load Balancing 5
Performance Optimization
Using PCI Bus Balancing 5
Bus Balancing Rules 5
Example Configurations 6
PCI Bus Loading with
PCI Hot Plug 7
PCI Bus
Balancing Tools 9
System Management
Performance Monitor 10
Balancing Bus Use 10
PCI Bus Loading with
Redundant Controllers 10
Online Storage Controller
Recovery Option 10
Compaq Advanced Network
Control Utility 10
Future PCI Bus Loading
and Technical Summary 11
PCI Bus Balancing and Optimization on
Compaq ProLiant Servers
With the introduction of dual-peer PCI (Peripheral Component Interconnect) bus
architecture, Compaq recommends balancing the load between the two PCI buses to
achieve optimal performance on the server.
This white paper identifies the importance of PCI Bus Balancing and provides technical
configurations for achieving high performance and availability on bridged PCI buses
and dual-peer PCI bus architectures.
Additional Resources include:
PCI Bus Numbering in a Microsoft Windows NT

Environment, First Edition,
February, 1998 – Doc ID ECG024/0298.
Configuring the Compaq

ProLiant 5000 Server for Peak Performance, Fourth Edition,
July 1997 – Doc ID 679A/0697.
Implementing Online Storage Controller Recovery Option Under Windows NT

, July
1997 - Doc ID ECG066A/0797.
Compaq Advanced Network Error Correction Support using PCI Hot Plug with
Microsoft Windows NT

, August 1997 – Doc ID ECG057/0897.
Compaq Advanced Network Error Correction Support in a Microsoft
Windows NT

Server Environment, June 1996 – Part Number 353A/0696.
Advanced Network Fault Detection and Correction Feature for NetWare

, June 1996 –
Part Number 385A/0696.

WHITE PAPER (cont.)
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ECG073/0398
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NOTICE
The information in this publication is subject to change without notice.
COMPAQ COMPUTER CORPORATION SHALL NOT BE LIABLE FOR TECHNICAL
OR EDITORIAL ERRORS OR OMISSIONS CONTAINED HEREIN, NOR FOR
INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM THE
FURNISHING, PERFORMANCE, OR USE OF THIS MATERIAL.
This publication does not constitute an endorsement of the product or products that were tested.
The configuration or configurations tested or described may or may not be the only available
solution. This test is not a determination of product quality or correctness, nor does it ensure
compliance with any federal, state or local requirements. Compaq does not warrant products
other than its own strictly as stated in Compaq product warranties.
Product names mentioned herein may be trademarks and/or registered trademarks of their
respective companies.
Compaq, Contura, Deskpro, Fastart, Compaq Insight Manager, LTE, PageMarq, Systempro,
Systempro/LT, ProLiant, TwinTray, ROMPaq, LicensePaq, QVision, SLT, ProLinea, SmartStart,
NetFlex, DirectPlus, QuickFind, RemotePaq, BackPaq, TechPaq, SpeedPaq, QuickBack, PaqFax,
Presario, SilentCool, CompaqCare (design), Aero, SmartStation, MiniStation, and PaqRap,
registered United States Patent and Trademark Office.
Netelligent, Armada, Cruiser, Concerto, QuickChoice, ProSignia, Systempro/XL, Net1, LTE
Elite, Vocalyst, PageMate, SoftPaq, FirstPaq, SolutionPaq, EasyPoint, EZ Help, MaxLight,
MultiLock, QuickBlank, QuickLock, UltraView, Innovate logo, Wonder Tools logo in black/white
and color, and Compaq PC Card Solution logo are trademarks and/or service marks of Compaq
Computer Corporation.
Other product names mentioned herein may be trademarks and/or registered trademarks of their
respective companies.
Copyright ©1998 Compaq Computer Corporation. All rights reserved. Printed in the U.S.A.
Microsoft, Windows, Windows NT, Windows NT Server and Workstation, Microsoft SQL Server
for Windows NT are trademarks and/or registered trademarks of Microsoft Corporation.
PCI Bus Balancing and Optimization on Compaq
ProLiant Servers
First Edition (March 1998)
Document Number: ECG073/0398

WHITE PAPER (cont.)
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ECG073/0398
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EXECUTIVE SUMMARY
With the introduction of the Compaq ProLiant 5000 Server and its dual-peer PCI (Peripheral
Component Interconnect) bus architecture, Compaq recommended certain configurations to
balance the load between the two PCI buses and achieve optimal performance on the server.
Customers now question what load balancing means, how it affects server performance and what
to consider for future planning and implementation of PCI bus loading.
This white paper identifies the overall importance of PCI bus balancing and provides technical
configurations for achieving high performance and availability on bridged and dual-peer PCI bus
architectures. The supporting facts presented along with recommendations will assist system
administrators and network operators in attaining and maintaining this goal.
PCI ARCHITECTURE
Two basic architectures are used to connect the primary and secondary PCI bus to the host bus:
the dual-peer PCI bus or the bridged PCI bus. The dual-peer bus architecture, as shown in
Figure 1, provides two PCI buses independently linked to the host processor bus by means of two
Host-to-PCI Bridges. Since each PCI bus runs independently, it is possible to have two PCI bus
masters transferring data simultaneously thus producing more overall throughput. This is an
advantage with systems that have two or more high-bandwidth peripherals. Splitting these
peripherals between the two buses provides an uniformed load.
Slots
Host Bus
Host Bus
Memory
Secondary PCI Bus
Host-
Host-
to-PCI
to-PCI
PCI-to-EISA
EISA Bus
33 MB/s
133 MB/s 133 MB/s
Primary PCI Bus
540 MB/s
Bridge Bridge
Bridge
Slots
Slots
Processors
Figure 1: Dual-peer PCI architecture.
The bridged PCI architecture, as shown in Figure 2, requires all processed transactions on the
bridged PCI bus (the secondary bus) to go through the PCI-to-PCI Bridge to reach the primary
bus, then through the Host-to-PCI Bridge. In effect there is only one path to the host bus;
therefore, no load balancing is required on a system with this type of architecture.
NOTE: Table 1 lists the
Compaq ProLiant family of
servers that embody the
dual-peer PCI bus architecture.
NOTE: Table 1 lists the
Compaq ProLiant family of
servers that embody the bridged
PCI bus architecture.

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ECG073/0398
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PCI-to-PCI
Bridge
Processors Memory
Host Bus
Host-to-PCI
Bridge
PCI Bus
133 MB/s
PCI Bus 133 MB/s
Slots
Slots
Figure 2: Bridged PCI architecture.
Knowing what PCI bus specific slots are assigned can be difficult to determine; therefore, Table 1
lists the slots for Compaq PCI bridged and dual-peer PCI servers and which bus they populate.
Use this matrix to identify which slot is assigned to the primary or secondary bus.
For any servers not listed, refer to the server user guide for the slot information or the Compaq
and Microsoft Windows NT Frontline Partnership web site located at:
http://www.compaq.com/solutions/frontline/pciutils.html.
TABLE 1: PCI BUS TO SLOT NUMBER ASSIGNMENTS
Slot
Number Bridged PCI Bus Systems Dual-Peer PCI Bus Systems
ProLiant 2500 ProLiant 1200 ProLiant 1600 ProLiant 3000/
ProLiant 5500 ProLiant 5000 ProLiant 6000/ ProLiant 7000 ProLiant 6500
1 Secondary Secondary Secondary Primary Primary
2 Secondary Secondary Secondary Primary Secondary Primary
3 Secondary Secondary Secondary Primary Secondary Primary Secondary
4 Primary Primary Primary Primary Secondary Primary Secondary
5 Primary Primary Primary Secondary Primary Primary Secondary
6 Primary Primary Primary Secondary Primary Primary Secondary
7 Secondary Primary Secondary Secondary
8 Secondary Primary Secondary Secondary
9Secondary
10 Secondary
11 Secondary

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PCI LOAD BALANCING
One key to procuring peak server performance is optimal configuration of the I/O (Input/Output)
subsystems. Because of architectural changes and enhancements incorporated into these systems,
careful consideration of load balancing must be given before the initial system setup and
configuration take place.
For example, the Intel Pentium Pro processor is optimized for performance using PCI peripherals.
The Compaq ProLiant servers that support dual-peer PCI bus architectures provide aggregate I/O
throughput capability as high as 267 MB/s. The dual-peer PCI bus architecture increases
configuration flexibility and allows higher levels of overall performance. However, attaining
peak performance requires careful evaluation of I/O loading across both PCI buses. This means
the administrator must carefully plan expansion slot usage for each device before initial
configuration, as well as plan for future expansion.
Performance Optimization Using PCI Bus Balancing
Bus balancing is achieved by balancing the I/O throughput on each bus, thus producing the
optimum performance on a system. However, not all PCI systems (i.e., bridged PCI systems)
achieve performance gains when implementing bus balancing; therefore, the customer has to
know when to balance the load on the system. Here are some brief recommendations. Detailed
configurations are described later in the document:
•For bridged architectures, load balancing is not required nor recommended. To obtain the
best performance on a bridged PCI system, the primary bus should be populated first.
•For dual-peer architectures load balancing is recommended. It could be helpful to split the
workload between buses when I/O throughput is high.
•For dual-peer architectures that have PCI Hot Plug slots, customers must consider the
trade-off between high availability and high performance. This is discussed in more detail
later in this document.
Bus Balancing Rules
Understanding how to balance the PCI load on a system can be confusing; therefore, some general
guidelines or rules for balancing bus traffic are provided:
1. When installing multiple network or array controllers, split the controllers between the buses.
2. If installing an "odd" number of controllers, for example, two NICs (Network Interface
Controller) and one drive array controller, split the two network controllers between the
buses. Network controllers consume more bandwidth than arraycontrollers do, so it is best to
split the workload between two buses if possible.
3. Avoid putting two network controllers together in the same bus unless both buses already
have a network controller installed. Note that it is better to have a system with one dual-port
NIC in each bus than to have two single-port NICs in each bus.

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Example Configurations
Table 2 explains where to place controllers to enable PCI bus balancing on Compaq ProLiant
servers that contain the dual-peer bus architecture. For example, a system configuration might
consist of one NIC and two drive array controllers (configuration #3 highlighted in Table 2). As
demands change and the system bandwidth needs to increase, the system administrator changes
the configuration to add another NIC to the system. As shown in configuration #4 (highlighted in
Table 2), the system administrator should place the new network controller on Bus X so the PCI
bus remains balanced.
TABLE 2: PCI BUS BALANCING IN A DUAL-PEER ARCHITECTURE
Config
#Device Type Bus X* Bus Y*
1 1 Network Interface Controller
1 Drive Array Controller Drive Array Controller Network Interface Controller
2 2 Network Interface Controllers
1 Drive Array Controller Network Interface Controller Drive Array Controller Network Interface Controller
31 Network Interface Controller
2 Drive Array Controllers Drive Array Controller Network Interface Controller Drive Array Controller
42 Network Interface Controllers
2 Drive Array Controllers Network Interface Controller Drive Array Controller Network Interface Controller Drive Array Controller
5 2 Network Interface Controllers
3 Drive Array Controllers Network Interface Controller 2 Drive Array Controllers Network Interface Controller Drive Array Controller
6 3 Network Interface Controllers
2 Drive Array Controllers 2 Network Interface Controllers Drive Array Controller
Optimal Preference:
1 DualPort Network Interface Controller
1 Drive Array Controller
Network Interface Controller
Drive Array Controller
Optimal Preference:
1 Network Interface Controller
1 Drive Array Controller
7 2 Network Interface Controllers
4 Drive Array Controllers Network Interface Controller 2 Drive Array Controllers Network Interface Controller 2 Drive Array Controllers
8 2 Network Interface Controllers
5 Drive Array Controllers Network Interface Controller 3 Drive Array Controllers Network Interface Controller 2 Drive Array Controllers
9 3 Network Interface Controller
4 Drive Array Controllers 2 Network Interface Controllers 2 Drive Array Controllers
Optimal Preference:
1 DualPort Network Interface Controller
2 Drive Array Controllers
Network Interface Controller
2 Drive Array Controllers
Optimal Preference:
1 Network Interface Controller
2 Drive Array Controllers
* Bus X and Y have no bearing to the primary and secondary bus. It could be either.

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PCI BUS LOADING WITH PCI HOT PLUG
For servers with PCI Hot Plug slots on a single bus, customers must pay close attention to
requirements for availability and determine whether a trade-off is needed between high
availability and high performance. Consider the following scenarios:
Configuration 1
For high availability and high performance, place the active controllers in the hot-plug slots, with
the standby controllers in the non-hot-plug slots. This splits the load so that a single NIC and
array controller is on each bus, as shown in Table 3.
This configuration provides moderately high availability along with high performance. However
since the standby network controller (#4) is in a non-hot-plug slot, if it were to fail replacing the
controller would require shutting down the server. The active NIC (#3), on the other hand, is still
available and in a hot-plug slot thus allowing the system administrator time to replace the failed
NIC (#4) during non-peak hours, when access to the server is at a minimum.
This configuration uses the minimum number of PCI hot-plug slots while providing redundancy
to controllers. It also enables hot replacement of the primary devices (active) in the event that
any of the active controllers should fail.
TABLE 3: HIGH AVAILABILITY AND HIGH PERFORMANCE
#Device Type PCI Hot Plug Slot Non-PCI HotPlug Slot
1 SMART 2/P Drive Array (Active) XXXXXX
2 SMART 2/P Drive Array (Standby) XXXXXX
3 NetFlex-3/P Controller (Active) XXXXXX
4 NetFlex-3/P Controller (Standby) XXXXXX
Configuration 2
If high availability is a primary concern, place all four controllers (active and standby) in the
hot-plug slots as shown in Table 4. Even though this configuration breaks rule number three in
the "Bus Balancing Rules" section, having two network controllers on the same bus does not
impact performance since the second NIC is in standby mode and therefore generates minimal
traffic on the bus.
This configuration works well for high availability because the I/O traffic emitted here is not
enough to saturate the PCI bus; therefore, there is no bottleneck to slow I/O traffic. If only two
NICs and two drive array controllers are needed, as in Table 4, both drive arrays and network
controllers could be placed on same bus without receiving any performance degradation.
TABLE 4: HIGHER AVAILABILITY AND HIGH PERFORMANCE
#Device Type PCI Hot Plug Slot Non-PCI HotPlug Slot
1 SMART 2/P Drive Array (Active) XXXXXX
2 SMART 2/P Drive Array (Standby) XXXXXX
3 NetFlex-3/P Controller (Active) XXXXXX
4 NetFlex-3/P Controller (Standby) XXXXXX

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Configuration 3
When the configuration consists of an additional stand-alone device, for example, a network
controller pair plus a single network controller, the active NIC should be on separate bus. If, on
the other hand, the customer has an arraycontroller pair plus a single arraycontroller, the active
array controllers should be on the same bus for best performance. Placing the stand-alone array
controller in a hot-plug slot provides similar performance to placing it in the non-hot-plug slot.
Since the performance is similar, using a hot-plug slot provides additional availability.
Table 5 displays a configuration using an additional stand-alone NIC. Placing the stand-alone
NIC in a non-hot-plug slot provides the best performance, as this configuration splits the active
NICs between buses. If availability is of greater concern than performance, place the stand-alone
NIC in a hot-plug slot.
TABLE 5: HIGH AVAILABILITY FOR ADDITIONAL STAND-ALONE DEVICES
#Device Type PCI Hot Plug Slot Non-PCI HotPlug Slot
1 SMART 2/P Drive Array (Active) XXXXXX
2 SMART 2/P Drive Array (Standby) XXXXXX
3 NetFlex-3/P Controller (Active) XXXXXX
4 NetFlex-3/P Controller (Standby) XXXXXX
5 NetFlex-3/P Controller (Stand-alone) XXXXXX
Configuration 4
For multiple pairs of network controllers, the same general guidelines apply. The customer must
evaluate the importance of availability and weigh that against any potential non-optimal
performance configurations.
Configuration 4 offers better availability than Configuration 3. Performance is optimal and a
higher level of availability is achieved. In the third configuration, if the standby network
controller failed, no network users would have access to any resources on that server while the
system administrator shuts down the system to replace the failed controller.
NOTE: A controller pair is
defined as two Compaq NICs that
are configured so that network
connectivity is maintained, even if
a connection is lost or a
controller fails. For more
information, refer to the white
paper "The Compaq Advanced
Network Error Correction
Support in a Microsoft Windows
NT Server Environment."

WHITE PAPER (cont.)
9
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If controller #5 fails in Configuration 4, network traffic would be "switched" or routed over to the
standby controller (#6), creating a slight decrease in performance because the bus is no longer
balanced. To eliminate the performance degradation, manually switch controller #3 to standby
mode and controller #4 to active mode, thus achieving a balanced load again. For details on how
to manually switch controllers using this utility, refer to the following white papers online at:
http://www.compaq.com/support/techpubs/index.html.
•Compaq Advanced Network Error Correction Support using PCI Hot Plug with Microsoft
Windows NT
•Advanced Network Fault Detection and Correction Feature for NetWare
Another benefit in using this configuration is that if a controller fails, the system administrator
can schedule downtime during non-business hours to replace the failed NIC. Once the
administrator, however, replaces the failed controller, the original controller should be switched
back to being the active controller.
The only limitation in this configuration is that one of the active network controllers is located in
a non-hot plug slot and therefore cannot be replaced while the system is running.
TABLE 6: HIGH AVAILABILITY FOR MULTIPLE NETWORK PAIRS
#Device Type PCI Hot Plug Slot Non-PCI HotPlug Slot
1 SMART 2/P Drive Array (Active) XXXXXX
2 SMART 2/P Drive Array (Standby) XXXXXX
3 NetFlex-3/P Controller (Active) XXXXXX
4 NetFlex-3/P Controller (Standby) XXXXXX
5 NetFlex-3/P Controller (Active) XXXXXX
6 NetFlex-3/P Controller (Standby) XXXXXX
PCI Hot Plug Balancing Review
Overall, the key to balancing the PCI bus is keeping the amount of data traffic on each bus
balanced. Use the following list of guidelines as a review for PCI Hot Plug bus balancing.
•When adding new controllers, keep the system balanced (see Table 2 for detailed
information).
•Evaluate the importance of high availability and weigh that against any potential non-optimal
performance configurations.
•If a controller fails, rebalancing of the system might be necessary to keep performance
optimal.
PCI BUS BALANCING TOOLS
Compaq offers a variety of helpful tools to assist in keeping the PCI busload balanced on Compaq
servers. Some tools specifically help users optimize their system containing PCI technology. A
brief description of each tool is provided.

WHITE PAPER (cont.)
10
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System Management Performance Monitor
Compaq offers Windows NT Performance Monitor Add-On Enhancement Tools toaid in theeasy
installation and removal ofObjectsand Object Countersfor theCompaq EISA and PCI Buses,
Power Supplyand NetFlex-3 Controllers.
TheSystem Management Performance Monitor, specifically, addsseveral System Management
ObjectstotheWindowsNT Performance Monitor. Thesecountersincludeitemsconcerning the
EISA Bus, PCI Bus, and Power Supply. Thesecounters requireCompaq Support Software
Version 1.21Aor later for Microsoft WindowsNT and Compaq Insight Manager 3.30 or later.
Thesetoolsareavailableon theCompaq Resource Paq for Microsoft WindowsNT. Toobtain a
copyoftheCompaq Resource Paq, gototheCompaq Microsoft FrontlinePartnership page
located on thewebat:
//www.compaq.com/solutions/frontline
Once theSystem Management Performance Monitor utilityisinstalled, viewthecounter data
collected bythedriversthrough thePerformance Monitor Utilityincluded with Microsoft
Windows NT.
Balancing Bus Use
Compaq Insight Manager supports bus usemeasurements on each PCI bus and on theEISA bus.
Thebususemeasurement toolsprovidea good waytocheck theI/Oconfiguration toensurethat
peripheralsareproperlybalanced across thetwoPCI buses. An indication ofunbalanced bususe
impliesthat thesystem might need tobereconfigured tooptimizeperformance. Refer toCompaq
Insight Manager documentation for moreinformation about using thesetools.
PCI BUSLOADINGWITH REDUNDANT CONTROLLERS
Compaq hasoffered manyinnovativesolutionstoreducing network downtimeon Compaq server
networks. Someofthesesolutionsinclude:
•OnlineStorageController RecoveryOption
•Compaq Advanced Network Control Utility
Online Storage ControllerRecoveryOption
TheCompaq OnlineStorageController RecoveryOption providesredundancyat themass storage
controller level bymerging twoSMART-2 controllers intoa controller pair. In such a pair, one
controller isactive, and theother remainsin standby mode. Should a problem occur with the
activecontroller, thedevice driver switchestraffictothestandbycontroller without loss ofdata or
interruption ofservice. Acompletedescription ofthisfault tolerance featurecan befound in the
whitepaper called Implementing Online Storage ControllerRecovery in WindowsNT, July 1997
– Doc ID 066A/0797.
Compaq Advanced Network Control Utility
TheCompaq Advanced Network Control Utilityisa network-monitoring tool that allowsa user to
install, uninstall, configureand monitor NetFlex-3 controllers. ThisutilityalsodisplaysPCI bus
number assignments, bustypeand slot numbersassociated with each device.
NOTE: Compaq Insight
Manager also monitors PCI bus
utilization on SCO UNIX and
Novell NetWare servers.
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WHITE PAPER (cont.)
11
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Acompletedescription ofall thecapabilitiesand featuresofthisutilityaredocumented in the
utilityHelp File, and in thewhitepaperCompaq Advanced Network ErrorCorrection Support
using PCI Hot Plug with Microsoft Windows NT, August 1997 – Doc ID ECG057/0897. This
whitepaper isavailableon theCompaq Resource Paq for WindowsNT.
Toobtain a copyoftheCompaq Resource Paq, gototheCompaq Microsoft FrontlinePartnership
pagelocated on thewebat:
//www.compaq.com/solutions/frontline
FUTUREPCI BUSLOADINGAND TECHNICAL SUMMARY
Compaq’sfirst server using PCI technologycontained a singlePCI bus. Ashort timelater,
Compaq introduced thedual-peer PCI busarchitecturehaving twoPCI busesindependently
linked tothehost processor bus, thusproviding thecapabilityofmoreI/Othroughput on the
server. As technologymovesforward, thenatural progression for PCI architecturecould moveto
three or morebuses. Thesamebusbalancing rulesdiscussed in thisdocument applytofuturebus
architectures.
Thekeyfor futurePCI busloading istobalance thesystem todaywhileplaning ahead for
tomorrow. It isimportant toremember toweigh thecurrent performance needsalong with future
performance requirements. For thisreason, trytochoosethebest performance configuration for
thecurrent server, and at thesametimeallowenough room in theconfiguration tofulfill growth
and increasing capacityrequirements. For instance, a server configuration currentlyconsistsof
onenetwork controller, yet planning for futurecapacityrequirementsdictatestheaddition oftwo
moreNICstotheserver. In thiscase, thenetwork administrator should purchasea dual-port NIC
tomeet thenewcapacityrequirementsand initiateredundancyon thisserver.
Beforemaking anymodifications, evaluateall ofthecurrent network server configurationsfirst.
Theserver configuration might not need tochange; therefore, thesystem administrator might not
havetoreconfigureall ofthemachinesifthePCI busesarecurrentlybalanced.
Aquestion toask is- "DoI need toreconfigureall ofmysystemstomakesurethePCI busesare
balanced?"Ifyour system consistsofjust a fewdevices(onenetwork controller and onedisk
arraycontroller), then thetotal PCI busbandwidth thedeviceswill usewill besmall compared to
theI/Othroughput capabilitiesofthePCI bus. In thiscase, therewould benosignificant
performance difference whether thecontrollerswereon thesamebusor split between buses. If
thesystem isusing multipledisk and network controllersand you need toimprovethe
performance ofyour system, then balancing thePCI buseson your system might improvethe
overall performance ofyour system.