Data Storage in Exchange Server

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Updated : September 11, 2001

from Chapter 3, Microsoft Exchange 2000 Administrator's Pocket Consultant by William R. Stanek.

Exchange Server stores information in two places:

  • Active Directory data store

  • Exchange Server information store

On This Page

Working with the Active Directory Data Store
Using and Managing Exchange Server Services

Working with the Active Directory Data Store

The Active Directory data store contains all directory information for recipients as well as other important directory resources. Domain controllers maintain the data store in a file called NTDS.DIT. The location of this file is set when Active Directory is installed and must be on an NTFS (NT file system) drive formatted for use with Microsoft Windows 2000. You can also save directory data separately from the main data store. This is true for some public data, such as logon scripts.

Two key concepts to focus on when looking at Active Directory are

  • Multimaster replication

  • Global catalog servers

Using Multimaster Replication

Domain controllers replicate most changes to the data store by using multimaster replication, which allows any domain controller to process directory changes and replicate those changes to other domain controllers. Replication is handled automatically for key data types, including

  • Domain data Contains information about objects within a domain, such as users, groups, and contacts.

  • Configuration data Describes the topology of the directory and includes a list of important domain information.

  • Schema data Describes all objects and data types that can be stored in the data store.

Using Global Catalogs

Active Directory information is also made available through global catalogs. You use global catalogs during logon and for information searches. A domain controller designated as a global catalog stores a full replica of all objects in the data store (for its host domain).

By default, the first domain controller installed in a domain is designated as the global catalog. Consequently, if there is only one domain controller in the domain, the domain controller and the global catalog are on the same server. Otherwise, the global catalog is on the domain controller configured as such.

Information searches are one of the key uses of the global catalog. Searches in the global catalog are very efficient and can resolve most queries locally, thus reducing the network load and allowing for quicker responses.

Working with the Exchange Server Information Store

The Exchange information store contains mailbox and public folder data. To make the information store more manageable, Exchange 2000 Server allows you to organize the information store into multiple databases. You can then manage these databases individually or in logical groupings called storage groups.

Exchange Server uses transactions to control changes in storage groups. As with traditional databases, these transactions are recorded in a transaction log. Changes are then committed or rolled back based on the success of the transaction. In the case of failure, you can use the transaction log to restore the database. The facility that manages transactions is the Microsoft Exchange Information Store service (STORE.EXE).

When working with storage groups, you should keep the following in mind:

  • Each Exchange server can have up to 16 storage groups (with one of the storage groups being reserved for database recovery operations).

  • A single storage group can have up to 6 databases. Thus, the maximum number of databases that a single server can have is 96 (with 6 reserved for the recovery storage group).

Key concepts to focus on when looking at the Exchange information store and storage groups are

  • Exchange Database formats

  • Single-instance message storage

  • Files associated with storage groups

What Exchange Server Database Formats Are Available?

Exchange servers store databases in two files: a rich-text file with the .edb file extension and a streaming Internet content file with the .stm file extension. The .edb file contains message text and the .stm file contains attachments to these messages.

Because attachments are written in native format, there is no need to convert attachments to Exchange format (as was done in previous versions of Exchange). Exchange Server performs much better when reading and writing attachments in native format.

Two types of databases are available:

  • Private store databases Contain mailboxes

  • Public store databases Contain public folders

What Is Single-Instance Message Storage?

Exchange Server uses single-instance message storage on a per database basis. With this technique, a message that's sent to multiple mailboxes is

  • Stored once if all the mailboxes are in the same database

  • Copied once to each database that contains a target mailbox

Additionally, if the databases are in different storage groups, Exchange Server writes the message to each database as well as the transaction log set for each storage group. Thus, a message written to three databases that are in two different storage groups would use five times the disk space as a message written to a single database in a single storage group. To see this, consider the following example:

A 2-MB message is sent to all company employees. The mailboxes for these employees are in private stores A and B in storage group 1 and in private store C in storage group 2. Exchange Server writes the message to the transaction log in storage groups 1 and 2 and then writes to the private storage databases A, B, and C. So storing the original 2-MB messages requires 10 MB of disk space.

Note: Needing 10 MB of disk space to store a 2-MB message may sound like an awful lot of space, but remember the hidden savings. That 2-MB message may have been sent to 1000 employees, and without single-instance message storage, Exchange Server would use a whopping 2 GB of disk space.

What Files Are Associated with Storage Groups?

Each storage group on Exchange Server has several files associated with it. These files are

  • EDB.CHK A check file containing recovered file fragments

  • EDB.LOG A transaction log file for the storage group

  • RES1.LOG A reserved log file for the storage group

  • RES2.LOG A reserved log file for the storage group

  • TMP.EDB A temporary workspace for processing transactions

  • DBName .EDB Rich-text database files for individual databases

  • DBName .STM Streaming Internet content files for individual databases

To create a new storage group with a public store and a private store, you'll need about 50 MB of free disk space. The files required by the storage group use a minimum of 11 MB of disk space. The minimum disk space for private and public stores is 5 MB and 8 MB, respectively. Although the total disk space used is about 24 MB, you'll need the extra space during creation and for read/write operations.

Using and Managing Exchange Server Services

Each Exchange server in the organization relies on a set of services for routing messages, processing transactions, replicating data, and much more. To manage Exchange services, you'll use the Services node in the Computer Management console, which you start by completing the following steps.

  1. Choose Start, choose Programs, choose Administrative Tools, and then select Computer Management. Or in the Administrative Tools folder, select Computer Management.

  2. Right-click the Computer Management entry in the console tree, and on the shortcut menu, select Connect To Another Computer. You can now choose the Exchange server whose services you want to manage.

  3. Expand the Services And Applications node by clicking the plus sign (+) next to it, and then choose Services.

Figure 3-3 shows the Services view in the Computer Manage console. The key fields of this window are used as follows:

  • Name The name of the service.

  • Description A short description of the service and its purpose.

  • Status The status of the service as started, paused, or stopped. (Stopped is indicated by a blank entry.)

  • Startup The startup setting for the service.

    Note: Automatic services are started at bootup. Manual services are started by users or other services. Disabled services are turned off and can't be started.

  • Account Run Under The account the service logs on as. The default in most cases is the local system account.


    Figure 3-3: . Use the Services node of the Computer Management window to manage Exchange Server services.

Using Core Exchange Server Services

Table 3-1 provides a summary of the services essential to normal Exchange operations. Note that the services that are available on a particular Exchange server depend on its configuration. Still, there is a core set of services that you'll find on most Exchange servers.

Table 3-1. Core Exchange Server Services



Distributed Transaction Coordinator

Coordinates transactions that are distributed across multiple databases, message queues, and file systems.

Event Log

Logs event informational, warning, and error messages issued by Exchange Server and other applications.

Internet Information Services (IIS) Admin Service

Allows you to administer the Exchange HTTP virtual server in the IIS snap-in.

Microsoft Exchange Event

Monitors folders and generates events for Exchange 5.5 applications.

Microsoft Exchange Internet Message Access Protocol (IMAP4)

Provides Microsoft Exchange IMAP4 services.

Microsoft Exchange Information Store

Manages Microsoft Exchange Information storage.

Microsoft Exchange Message Transfer Agent (MTA) Stacks

Provides Microsoft Exchange X.400 services.

Microsoft Exchange POP3

Provides Microsoft Exchange POP3 services.

Microsoft Exchange Routing Engine

Processes Microsoft Exchange message routing and link state information.

Microsoft Exchange Site Replication Service

Replicates Exchange information within the organization.

Microsoft Exchange System Attendant

Monitors Microsoft Exchange and provides essential services.

Network News Transport Protocol (NNTP)

Transports newsgroup messages across the network.

Simple Mail Transport Protocol (SMTP)

Transports e-mail across the network.

World Wide Web Publishing Service

Provides HTTP services for Microsoft Exchange Server and Internet Information Services.

Starting, Stopping, and Pausing Exchange Server Services

As an administrator, you'll often have to start, stop, or pause Exchange services. You manage Exchange services through the Computer Management console or through System Manager.

To start, stop, or pause services in the Computer Management console, follow these steps.

  1. Right-click the Computer Management entry in the console tree, and on the shortcut menu, select Connect To Another Computer. You can now choose the Exchange server whose services you want to manage.

  2. Expand the Services And Applications node by clicking the plus sign (+) next to it, and then choose Services.

  3. Right-click the service you want to manipulate, and then select Start, Stop, or Pause as appropriate. You can also choose Restart to have Windows stop and then start the service after a brief pause. Also, if you pause a service, you can use the Resume option to resume normal operation.

    Tip When services that are set to start automatically fail, the status is listed as blank and you'll usually receive notification in a pop-up window. Service failures can also be logged to the system's event logs. In Windows 2000, you can configure actions to handle service failure automatically. For example, you could have Windows 2000 attempt to restart the service for you. See the section of this chapter entitled "Configuring Service Recovery" for details.

Several of the Exchange services are used to manage the Exchange virtual servers. These services are

  • Microsoft Exchange IMAP4 for the IMAP4 virtual server

  • Microsoft Exchange POP3 for the POP3 virtual server

  • NNTP for the NNTP virtual server

  • SMTP for the SMTP virtual server

If you start, stop, or pause these services in the Computer Management console, you're managing the related virtual server as well. You can also use System Manager to perform these tasks. To do that, complete the following steps.

  1. In System Manager, access the Servers node within the administrative or routing group you want to manage. Typically, you would expand Administrative Groups, First Administrative Group, and then the Servers node.

  2. In the console tree, select the Exchange server you want to manage, and then double-click Protocols. You should now see a list of protocols installed on the server.

  3. The Protocol folder stores related virtual servers. For example, the IMAP4 folder stores the Default IMAP4 virtual server and any other IMAP4 virtual servers you've created.

  4. Right-click the virtual server you want to start, stop, or pause, and then on the shortcut menu, select Start, Stop, or Pause as appropriate.

Configuring Service Startup

Essential Exchange services are configured to start automatically and normally shouldn't be configured with another startup option. That said, if you're troubleshooting a problem, you may want a service to start manually. You may also want to disable a service so that its related virtual servers don't start. For example, if you move the POP3 virtual servers to a new server for load balancing, you may want to disable the Microsoft Exchange POP3 service on the original Exchange server. In this way, the POP3 service isn't used, but it could be turned on if necessary (without having to reinstall POP3 support).

You configure service startup by completing the following steps.

  1. In the Computer Management console, connect to the Exchange server whose services you want to manage.

  2. Expand the Services And Applications node by clicking the plus sign (+) next to it, and then choose Services.

  3. Right-click the service you want to configure, and then choose Properties.

  4. In the General tab, use the Startup Type selection list to choose a startup option, as shown in Figure 3-4. Select Automatic to start services at bootup. Select Manual to allow services to be started manually. Select Disabled to turn off services.

  5. Click OK.


    Figure 3-4: . For troubleshooting, you may want to change the service startup option in the Properties dialog box.

Configuring Service Recovery

You can configure Windows services to take specific actions when a service fails. For example, you could attempt to restart the service or reboot the server. To configure recovery options for a service, follow these steps.

  1. In the Computer Management console, connect to the computer whose services you want to manage.

  2. Expand the Services And Applications node by clicking the plus sign (+) next to it, and then choose Services.

  3. Right-click the service you want to configure, and then choose Properties.

    Select the Recovery tab, as shown in Figure 3-5. You can now configure recovery options for the first, second, and subsequent recovery attempts. The available options are

    • Take No Action

    • Restart The Service

    • Run A File

    • Reboot The Computer

  4. Configure other options based on your previously selected recovery options. If you elected to restart the service, you'll need to specify the restart delay. After stopping the service, Windows 2000 waits for the specified delay period before trying to start the service. In most cases a delay of 1–2 minutes should be sufficient.

  5. Click OK.


    Figure 3-5: . By using the Recovery tab in the Properties dialog box, you can configure services to automatically recover in case of failure.

When you configure recovery options for critical services, you may want to try to restart the service on the first and second attempts and then reboot the server on the third attempt.

from Microsoft Exchange 2000 Administrator's Pocket Consultant by William R. Stanek. Copyright © 1999 Microsoft Corporation.

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