Step-by-Step Guide to Increasing the Exchange 2003 Private Mail Store Size on Windows Small Business Server 2003

Note
The information in this document applies to the Microsoft® Windows® Small Business Server 2003 server software with Service Pack 1 or to Windows Small Business Server 2003 R2 (Windows SBS). The intended audience for this document is administrators of Windows SBS.

Note
The skill level required to complete the steps in this document assumes a working knowledge of how to install, configure, and manage Microsoft Exchange Server 2003, and experience editing the registry.

Exchange Server 2003 creates and maintains a private mail store where all mailboxes and e-mail are kept. The size of the mail store determines how much storage space is available for all mailboxes and e-mail on your server. Service Pack 2 (SP2) for Exchange Server 2003 automatically increases your private mail store from 16 gigabytes (GB) to 18 GB. The service pack also enables you to increase your private mail store and your public folder store to 75 GB each. If you increase your stores beyond 18 GB, you must make sure that you have enough disk space for your database, prepare your server with the necessary hardware and software updates, and then edit the registry to set the new database size. This document takes you step-by-step through the process of increasing your private mail store size.

Before You Begin

Read this document completely before you begin to increase the private mail store size. Then analyze your situation and the requirements for your e-mail server. Although increasing the size of the private mail store may seem like the best way to increase storage capacity, it involves some trade-offs. When you increase the size of the private mail store, you must consider how to back up the mail store. You may find it easier to manage your private mail store if you implement retention policies that reduce the amount of data that needs to be stored.

If you decide to increase the size of your private mail store, you should calculate the disk space requirements for your increased store size and then prepare your server with any necessary hardware and software upgrades. Depending on your current configuration, you may need to purchase and install additional hardware and software to support the new store size.

Important

This paper contains information about editing the registry. Before you edit the registry, make a backup of the registry items that you intend to edit, and change only the ones that are discussed in this document. Make sure that you understand how to restore the registry if a problem occurs. For information about how to restore the registry, clickStart, click Run, type regedit.exe, click OK, and then search for the "Restore the Registry" Help topic.

Calculate the Disk-Space Requirements

Before you increase the size of your private mail store, calculate how much hard drive space is being used for all of the data on your server. This includes the private mail store, the public folder store, the transaction logs, and the other storage repositories on your server. You may find that significant amounts of storage are being used by the \\ServerName\Users and \\ServerName\ClientApps shared folders, the http://companyweb Web site, Windows Server Update Services, and any databases that your line-of-business applications are using. By calculating how much hard drive space is already being used, you can determine whether you need additional storage for Exchange, for users' files, or for all of your data that is stored on your server. You can then determine how much additional hard drive space you need for your private mail store.

You should consider the following five factors when you determine the hard drive space requirements:

• Available hard drive space. If your private mail store is going to grow, make sure you have enough hard drive space available. If you set the private mail store size greater than the amount of space that is available on the hard drive, Exchange will go offline when you have only 2 MB of unused hard disk drive space remaining. When this happens, either you must make the private mail store smaller by using the eseutil tool to defragment the store, or you must manually make room on the hard drive by deleting other files and folders.
  
• User mailbox quotas. The size of the private mail store is approximately equal to the global user mailbox quota multiplied by the number of user mailboxes. In many cases, you can make additional space available by managing the global and individual quotas, reducing mailbox size for non-essential employees and increasing it for mission-critical accounts. Calculate how much additional space you need by using the Calculation Worksheet that follows this list. If you increase quotas for some accounts to be more than the global quota, the actual private mail store size is larger.
  
• Room for growth. The size of your private mail store can grow either because you add more employees or because those employees are working with large, media-rich documents and e-mail attachments. It is easier to increase the private mail store size on existing hard disk drives than it is to purchase, install, and restore a database onto new hard disk drives. Therefore if you are purchasing new hard disk drives for your server, consider purchasing as much storage space as you can afford. This gives you room for growth in the future.
  
• Disaster recovery. If a disaster strikes but your server has insufficient space available, it can be difficult to restore your private mail store. To avoid this, a good guideline is to reserve an amount of space that is equal to the private mail store size plus ten percent. For example, if you estimate that your private mail store will grow to a maximum size of 30 GB, make sure that you have at least 33 GB (30 GB + 10%) of unused space on your hard drive. This way, you can defragment the private mail store offline. If this amount of additional storage is not available, you may have to copy your private mail store onto your server over the network (or buy and install additional hard drives) before you can begin disaster-recovery procedures.
  
• Backup and restore restrictions. Larger stores take more time to back up and to restore. It is recommended that you increase the private mail store size by only 5-10 GB at a time and that you monitor the length of time needed to back up the store each night. If the backup takes too long, you can choose whether to start the backup earlier, to switch to a different backup medium (for example, from tape to removable hard disk drives), to buy faster hard disk drives and drive controllers, or to move other data files onto a server that is running a separate backup program. With additional storage needs, you may require multiple tapes to complete a backup, which in turn requires either that you have a multi-tape backup device or that someone is available to change the tapes. Use the following table to help you calculate the total hard drive space that you need for your server.
  

 

Calculation Worksheet
Available hard disk drive space
Number of users
Current mailbox quota
Total space required by mailboxes
Room for growth (Optional)
Total database size
Disaster recovery (Optional)
Total hard disk drive space needed

Prepare Your Server

Before you increase the size of the private mail store, complete the following steps:

• Install and configure any additional hard drives that you may need,
  
• Uninstall Exchange Intelligent Message Filter v1 (if it is installed).
  
• Bring your server up to date with the necessary service packs.
  
• Back up your server, including the Exchange stores and the system state.
  

These steps prepare your server so that it will properly use the increased store size. You must also ensure that you do not run out of disk space after you make the changes. You should allow enough space to defragment an Exchange store with the eseutil tool and to restore individual mailboxes with the exmerge tool, if you need to. For more information about eseutil, see Article 328804, "How to defragment Exchange databases," at the Microsoft Knowledge Base (http://go.microsoft.com/fwlink/?LinkID=67333). For more information about exmerge, see the online Help for Exchange Server 2003.

Install and configure any additional hard disk drives that you may need. After you decide on the new size for your private mail store, decide whether you have enough disk space for the new store size. You may need to purchase and install new hard drives. These drives must be available on the server and not network-attached storage or shared folders on other servers.

If you need to add several hard drives to support your storage requirements, consider purchasing an additional server for your non–Windows SBS applications. You can then move your applications and related data to the new server, leaving room for the private mail store on your server that is running Windows SBS. You can also move some of your Windows SBS data folders to other hard drives or RAID arrays on the server that is running Windows SBS. For more information about how to move data folders, see "Moving Data Folders for Windows Small Business Server 2003" at the Microsoft Web Site (http://go.microsoft.com/fwlink/?LinkID=65117).

Uninstall Exchange Intelligent Message Filter v1. If you are running Exchange Intelligent Message Filter (IMF) v1 on Exchange Server 2003, you need to uninstall it before you install SP2 for Exchange Server 2003. SP2 for Exchange Server 2003 contains IMF v2, which does not work with v1 when it is installed on the same server. For more information about using IMF v2, see "Exchange Intelligent Message Filter" at the Microsoft Web site (http://go.microsoft.com/fwlink/?LinkID=65118).

Bring your server up to date with the necessary service packs. If your server is running Windows SBS 2003, you must obtain and install both SP1 for Windows SBS and SP2 for Exchange Server 2003. To install SP1 for Windows SBS 2003, see "Microsoft Windows Small Business Server 2003 Service Pack 1 (SP1)" at the Microsoft Web site(http://go.microsoft.com/fwlink/?LinkID=46690). To install SP2 for Exchange Server 2003, see "Exchange Server 2003 Service Pack 2" at the Microsoft Web site(http://go.microsoft.com/fwlink/?LinkID=65119).

If your server is running Windows SBS 2003 R2, you do not need to install additional software. Windows SBS 2003 R2 includes SP2 for Exchange Server 2003.

Back up your server, including the Exchange stores and the system state. You should test the backup by recovering a single e-mail message or by restoring a user's mailbox to verify that the backup is working properly. For more information, see "Backing Up and Restoring Windows Small Business Server 2003" at the Microsoft Web site(http://go.microsoft.com/fwlink/?LinkID=49916).

Process Steps for Increasing the Size of the Private Mail Store

To increase the size of the private mail store, complete the following steps:

1. Set the private mail store size, buffer size, and database check time.
   
2. Set the global mailbox quota.
   
3. Dismount and then remount the Exchange database.
   

Step 1: Set the private mail store size, buffer size, and database check time

When you increase the size of the private mail store, you must create three new registry entries: Database Size Limit in GB, Database Size Buffer in Percentage, and Database Size Check Start Time in Hours From Midnight. These three entries work together to set the size of the mail store and to post warning events in the Application Log when the store nears capacity.

Note

When you install Windows SBS, Exchange creates individual registry entries for the private mail store and public folder store, and it appends the Active Directory GUID (globally unique identifier) of the Exchange server to the registry entries. Rather than referring to the full names of the registry entries throughout these instructions, the term is shortened to Private-GUID and Public-GUID as appropriate. When you work with the registry, make changes to the appropriate registry entry.

Caution

SP2 for Exchange Server 2003 does not ensure that your private mail store size change is valid. You can lose data if you set the private store size larger than your actual hard drive space or if you set user mailbox quotas so that the total quota size exceeds your private mail store size. Use the Calculation Worksheet earlier in this document to make sure that you do not exceed any physical or logical limits on your drives or databases.

To set the size of the private mail store

1. Click Start, click Run, type regedit, and then click OK. Regedit starts.
2. Browse to HKEY_LOCAL_MACHINE/ System/ CurrentControlSet/ Services/ MSExchangeIS/ ServerName, where ServerName is the name of your server that is running Windows SBS.
3. To modify the private mail store size, right-click the Private-GUID folder, click New, and then click DWORD Value.
4. Type Database Size Limit in GB, and then press ENTER.
5. Right-click the new entry and then click Modify.
6. In the Base field, click Decimal. In the Value data text box, type a number between 1 and 75. This is the new maximum size of your database in gigabytes.
7. Click OK.
8. Close Regedit.

Next, set the database buffer size so that Exchange posts warning events in the Application Log when the private mail store is nearing its maximum capacity. This way, you can respond by telling users to clean out their mailboxes, by increasing capacity with additional hard disk drives, or by increasing the private mail store size.
To set the size of the buffer

1. Click Start, click Run, type regedit, and then click OK. Regedit starts.
2. Browse to HKEY_LOCAL_MACHINE/ System/ CurrentControlSet/ Services/ MSExchangeIS/ ServerName, where ServerName is the name of your server that is running Windows SBS.
3. To set a buffer size for the private mail store, right-click the Private-GUID folder, click New, and then click DWORD Value.
4. Type Database Size Buffer in Percentage, and press ENTER.
5. Right-click the new value and then click Modify.
6. In the Base field, click Decimal. In the Value data text box, type a number between 1 and 100. A value of 10, for example, results in warning events being logged when the database has 10 percent capacity remaining.
7. Click OK.
8. Close Regedit.

Lastly, set the time when Exchange checks the private mail store size to see if it exceeds the buffer limit.

Note
It is recommended that you set the time to occur during regular business hours so that you can respond to the low storage space before the Exchange mail store goes offline.

To set the time for checking the size of the private mail store

1. Click Start, click Run, type regedit, and then click OK. Regedit starts.
2. Browse to HKEY_LOCAL_MACHINE/ System/ CurrentControlSet/ Services/ MSExchangeIS/ ServerName, where ServerName is the name of your server that is running Windows SBS.
3. To set a check time for the private mail store, right-click the Private-GUID folder, click New, and then click DWORD Value.
4. Type Database Size Check Start Time in Hours From Midnight, and then press ENTER.
5. Right-click the new entry, and then click Modify.
6. In the Base field, click Decimal. In the Value data text box, type a number between 0 and 23. A value of 10, for example, means that Exchange Server checks the private mail store size 10 hours after midnight (10:00 A.M.). Click OK.
7. Close Regedit.

Step 2: Set the global mailbox quota

You can set mailbox quotas either for all mailboxes on the server or for an individual mailbox. To set the default mailbox quota for all mailboxes on the server, complete the following procedure.
To set the global mailbox quota

1. Click Start, and then click Server Management.
2. Click Advanced Management, click First Organization (Exchange), click Servers, click SERVER, click ServerName, where ServerName is the name of your server that is running Windows SBS, and then click First Storage Group. Note that after you click First Organization (Exchange), it changes to the name of your server that is running Windows SBS.
3. Right-click Mailbox Store (SERVER), and then click Properties.
4. Click the Limits tab.
5. Select Issue warning at (KB), and then type the new warning value in kilobytes (KB).
6. Click Prohibit send at (KB), and then type the new mailbox send limit in kilobytes.
7. Select Prohibit send and receive at (KB), and then type the new mailbox limit for all functions in kilobytes. The Prohibit send and receive value should be the new mailbox quota for each mailbox.
8. Click OK.
9. Close the Server Management console.

You can also set quotas for individual mailboxes. This is not recommended as a general practice, because it is easy to lose track of which mailboxes have been modified and how your maximum database size has been affected. If you need to change the quota for an individual mailbox, complete the following procedure.
To set an individual mailbox quota

1. Click Start, click Server Management, and then click Users.
2. Right-click a user name, and then click Properties.
3. Click the Exchange General tab, and then click Storage Limits.
4. In the Storage Limits section, clear the Use mailbox store defaults check box.
5. Select Issue warning at (KB), and then type the new warning value in kilobytes.
6. Select Prohibit send at (KB), and then type the new mailbox send limit in kilobytes.
7. Select Prohibit send and receive at (KB), and then type the new mailbox limit for all functions in kilobytes. The Prohibit send and receive value should be the new mailbox quota for each mailbox.
8. Click OK.
9. Close the User console.

Step 3: Dismount and then remount the Exchange database

You must dismount and then remount the Exchange database for your registry changes to take effect.

Important
When you dismount the database, the users cannot access Exchange (including Outlook, Outlook Web Access, and Outlook Mobile Access) until you remount the database. You should dismount and remount the database when the disruption is least likely to affect the users.

To dismount and then remount the Exchange database

1. Click Start, and then click Server Management.
2. Click Advanced Management, click First Organization (Exchange), click Servers, click SERVER, click ServerName, where ServerName is the name of your server, and then click First Storage Group. Note that after you click First Organization (Exchange), it changes to the name of your server that is running Windows SBS.
3. Right-click Mailbox Store (SERVER), and then click Dismount store. When the alert appears, click Yes.
4. When the database has been dismounted, right-click Mailbox Store (SERVER), and then click Mount store. When the success dialog appears, click OK.
5. Close the Server Management console.

After you remount the database, the size of your new private mail store appears in the Application Log in Event ID #1216. When the buffer limit for the mail store size is reached, Event ID #9688 appears in the Application Log. If the limit is exceeded, the Exchange database is dismounted and Event ID #9690 appears in the Application Log. Rebooting the machine or restarting the ExchangeIS service does not remount the database. Instead, you must increase the database size in the registry, defragment the database, or make more room available on the hard disk drive.