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Baseline Performance for Mailbox Server (Using MAPI)

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This section provides baseline performance data on Exchange Server 2003 mailbox server under specific MAPI client loads. The key hardware criteria for a mailbox server are processor type and speed, memory size, network speed, and disk performance and configuration.

Note

Exchange 2000 Server scalability data is used as a basis for comparison. Load Simulator 2000 and Load Simulator 2003 are used to simulate Outlook 2000 and Outlook 2003 MAPI clients respectively. For more information about Load Simulator (LoadSim), see Exchange Server 2003 Performance Tools.

Hardware

The following table shows the hardware specifications used in the following scenarios:

  • Scenario 1: Exchange 2000 Server and Outlook 2000 Online versus Exchange Server 2003 and Outlook 2003 Online

  • Scenario 2: Exchange 2000 Server and Outlook 2003 Cached Exchange Mode versus Exchange Server 2003 and Outlook 2003 Cached Exchange Mode

Mailbox hardware configuration

Server type Processor type RAM Storage

Back-end server

Intel P4 Xeon 4 processors, 1.4 GHz (Hyper-Threading disabled)

4 GB

  • SAN with RAID0+1 for database volumes

  • 2 spindles of RAID1 for each transaction logs for each storage group

  • 8,000 users were spread evenly across 12 databases, in three storage groups with an average user mailbox size of 25 MB

Scenario 1: Exchange 2000 Server and Outlook 2000 Online vs. Exchange Server 2003 and Outlook 2003 Online

This scenario compares the load characteristics of Exchange 2000 Server and Outlook 2000 with Exchange Server 2003 and Outlook 2003. Load Simulator 2003 is used to generate the load. The following LoadSim configuration was used:

  • LoadSim Client Configuration

    • Intel P4 600 megahertz (MHz)

    • 512 MB RAM

    • Single Integrated Drive Electronics (IDE) disk

    • 1,000 LoadSim clients per computer

  • LoadSim Configuration   The following tables show the values that were used.

    Mailbox configuration settings

    Mailbox configuration Value

    Messages in Inbox

    100

    Message in Deleted Items

    1

    Number of new folders

    10

    Messages per new folder

    10

    Calendar Appointments

    25

    Number of Contacts

    128

    Average Message Size

    75 KB

    User action settings

    User actions per 8-hour day Value

    Send Mail

    12

    Messages Received/day

    208

    Messages Sent/day

    52

    Process Inbox

    12

    Browse Mail

    20

    Check Free/Busy

    1

    Request Meeting

    1.4

    Make Appointment

    2.8

    Browse Calendar

    6

    Journal Applications

    0

    Logoff

    0

    Browse Contacts

    0

    Create Contact

    0

    Distribution list settings

    Distribution lists Value

    Distribution lists per site

    100

    Minimum distribution list size

    2

    Average distribution list size

    10

    Maximum distribution list size

    20

The following table shows the results produced by the mailbox server in this scenario.

Mailbox server performance comparison

Server platform Windows 2000 SP3 Windows 2000 SP3 Windows Server 2003 Windows Server 2003

Exchange platform

Exchange 2000 Server SP3

Exchange Server 2003

Exchange Server 2003

Exchange Server 2003

Client platform

Windows XP, Outlook 2000 Online

Windows XP, Outlook 2003 Online

Windows XP, Outlook 2003 Online

Windows XP, Outlook 2003 Online

Hyper-Threading enabled?

No

No

No

Yes

Users

8,000

8,000

8,000

8,000

% Processor Time

75%

76%

75%

57%

Context Switches/sec

8,300

7,833

10,183

13,487

Local Delivery Rate

30

30

30

30

Network Usage (in Kbps)

3,154

1,594

1,604

1,613

DB Disk Transfers/sec

2,088

1,980

1,929

1,955

Log Writes/sec

377

314

353

398

Disk Bytes/sec (MB)

19.9

20.4

18.9

17.9

Database Cache Size

864

896

896

896

RPC Operations/sec

950

955

940

925

RPC Requests

7

8

8

7

Client Latency (ms)

96

100

95

105

Store Virtual Bytes

2,047

2,075

2,080

2,082

For more information about the performance counters used in this scenario, see Performance Counter Definitions.

Processor

Exchange 2000 Server SP3 and Exchange Server 2003 show comparable levels of processor performance. The 8,000-user Exchange 2000 Server SP3 test reaches 75 percent processor usage, and the Exchange Server 2003 test reaches 76 percent processor usage. Both tests show similar workloads (950 RPC Operations/sec to 955, with the same Local Delivery Rate).

The table above shows that Windows 2000 Advanced Server with SP3 and Windows Server 2003, perform comparably in terms of processor usage when running Exchange Server 2003. However, Windows Server 2003 has key memory manager optimizations that significantly reduce virtual memory fragmentation, which is not shown in the table.

Exchange Server 2003 takes advantage of Intel Hyper-Threading Technology to increase server scalability by 25 percent. This table shows that processor use is reduced by 25 percent (from 76 percent to 57 percent) when the same test is run with Hyper-Threading enabled. The benefit of Hyper-Threading is the same for Cached Exchange Mode client scenarios.

Memory

The Exchange store memory footprint of Exchange Server 2003 is approximately the same as that of Exchange 2000 Server. With the increase in Database Cache Size (896 MB compared to 864 MB) in Exchange Server 2003 and performance improvements in Jet, random Exchange store disk I/O operations can be reduced by up to 10 percent.

Disk Usage

Exchange Server 2003 produces 10 percent fewer Exchange database disk I/O operations than Exchange 2000 Server SP3. Because of the increase in Database Cache Size (896 MB compared to 864 MB) in Exchange Server 2003, random Exchange database disk I/O operations can be reduced by up to 10 percent.

Network Usage

Exchange Server 2003 and Outlook 2003 can reduce network bandwidth when compared to Exchange 2000 Server and Outlook 2000 by up to 50 percent. This 8,000-user test shows that Exchange 2000 Server and Outlook 2000 use 3,154 Kbps, and Exchange Server 2003 and Outlook 2003 use approximately half the bandwidth at 1,594 Kbps. Because of the compression technology implemented in Exchange Server 2003 and Outlook 2003, the network bandwidth required to host a particular number of users is significantly less than that of Exchange 2000 Server and Outlook 2000. Many performance optimizations were implemented in Exchange Server 2003 so this compression would not detract from the scalability of the server. In effect, the reduction of bytes over the wire is free in terms of server CPU usage.

Scenario 2: Exchange 2000 Server and Outlook 2003 Cached Exchange Mode vs. Exchange Server 2003 and Outlook 2003 Cached Exchange Mode

This test compares the load characteristics of Exchange 2000 Server and Outlook 2003 with Exchange Server 2003 and Outlook 2003 in a Cached Exchange Mode client scenario. LoadSim 2003 is used to generate the load.

  • LoadSim Client Configuration

    • Intel P4 600 MHz

    • 512 MB RAM

    • Single IDE disk

    • 1,000 LoadSim clients per computer

  • LoadSim Configuration   The following tables show the values that were used.

    Mailbox configuration settings

    Mailbox configuration Value

    Messages in Inbox

    100

    Message in Deleted Items

    1

    Number of new folders

    10

    Messages per new folder

    10

    Calendar Appointments

    25

    Number of Contacts

    128

    Average Message Size

    75 KB

    User action settings

    User actions per eight-hour day Value

    Send Mail

    7

    Messages Received/day

    161.90

    Messages Sent/day

    44.12

    Process Inbox

    20

    Browse Mail

    0

    Check Free/Busy

    4

    Request Meeting

    2

    Make Appointment

    4

    Browse Calendar

    1

    Journal Applications

    0

    Logoff

    3

    Browse Contacts

    0

    Create Contact

    0

    User action settings

    Distribution lists Value

    Distribution lists per site

    100

    Minimum distribution lists size

    2

    Average distribution lists size

    10

    Maximum distribution lists size

    20

The following table shows the results produced by the mailbox server in this scenario.

Exchange 2000 Server/Exchange Server 2003 Cached Mode comparison

Server platform Windows 2000 SP3 Windows 2000 SP3

Exchange platform

Exchange 2000 Server SP3

Exchange Server 2003

Client platform

Windows XP, Outlook 2003 Cached Exchange Mode

Windows XP, Outlook 2003 Cached Exchange Mode

Hyper-Threading enabled?

No

No

Users

8,000

8,000

% Processor Time

64%

57%

Context Switches/sec

7,981

6,488

Local Delivery Rate

23

23

Network Usage (in Kbps)

3,613

1,765

DB Disk Transfers/sec

1,496

1,355

Log Writes/sec

304

315

Disk Bytes/sec (MB)

17.7

16.2

Database Cache Size

896

864

RPC Operations/sec

1,205

1,193

RPC Requests

8

7

Store Virtual Bytes

2,016

2,076

For more information about the performance counters used in this scenario, see Performance Counter Definitions.

Note

Results of the Outlook 2003 online tests and the Outlook 2003 Cached Exchange Mode tests are not comparable. The user profile and user actions are quite different. For specific performance data about Outlook 2003, see Client Network Traffic with Exchange Server 2003.

Processor

In this test, processor performance of Cached Exchange Mode MAPI clients on Exchange Server 2003 is approximately 10 percent better than Exchange 2000 Server SP3. The 8,000-user Exchange 2000 Server SP3 test reaches 64 percent processor usage, and the Exchange Server 2003 test reaches 57 percent processor usage. Both tests show similar workloads (1,193 RPC Operations/sec compared to 1,205, with the same Local Delivery Rate). Exchange 2003 Server is optimized for Outlook 2003 Cached Exchange Mode clients.

Memory

The Exchange store memory footprint of Exchange Server 2003 is approximately the same as that of Exchange 2000 Server. With the increase in Database Cache Size (896 MB compared to 864 MB) on Exchange Server 2003 and performance improvements in Jet, the random Exchange database disk I/O operations can be reduced by up to 10 percent.

Disk Usage

Exchange 2003 produces 10 percent fewer Exchange database disk I/O operations than Exchange 2000 Server SP3. Because of the increase in the size of the database cache (896 MB compared to 864 MB) in Exchange Server 2003, the random Exchange database disk I/O operations can be reduced by up to 10 percent.

Network Usage

Exchange Server 2003 and Outlook 2003 can reduce the network bandwidth when compared to Exchange 2000 Server and Outlook 2003 by up to 50 percent. This 8,000-user test shows Exchange 2000 Server and Outlook 2003 uses 3,613 Kbps, and the Exchange Server 2003 and Outlook 2003 test uses approximately half the bandwidth at 1,765 Kbps. Because of the compression technology implemented in Exchange Server 2003 and Outlook 2003, the network bandwidth required to host a particular number of users is significantly less than that of Exchange 2000 Server and Outlook 2003. Many performance optimizations were implemented in Exchange Server 2003 so this compression would not detract from the scalability of the server. In effect, the reduction of bytes over the wire is free in terms of server CPU usage.

Mailbox Scalability Guidelines

When you design a mailbox server, consider the following recommendations.

  • A back-end mailbox server hosting many MAPI connections scales well on 4-processor servers.

  • Generally, one processor for every 1,000 users is a good guideline for all but the heaviest of mail users. For more information on processor requirements, see Calculate Your Server Size.

  • Exchange Server uses a maximum of 3 GB of memory. To increase performance, increase memory up to 4 GB to reduce the paging to disk.