Exchange Server 2003 Data Storage and Management

Understanding Exchange Server 2003 Data Storage

Exchange Server 2003 uses the Extensible Storage Engine (ESE) database structure to store data. Data can be stored separately for messages and for transactions:

A message that is created is first written to log files before it is written to the database files. From the log files, the transactions are sequentially written to a numbered file. Data in the log file is written to the database at a later stage.
Transaction log files are written to in a sequential order. Database files are written to in a random manner. They are also read in a random manner. Exchange Server 2003 automatically creates a new transaction log file when the current log file reaches 5 megabytes (MB) in size.

The transaction log files and database files should be located on disk systems that have the following characteristics:

The disk setup that you use for transaction log files and database files should provide the following:

You can use redundant array of independent drives (RAID) systems in Exchange Server 2003. There are software and hardware RAID implementations:

The commonly used RAID implementations in Exchange Server 2003 are listed here:

Disk mirroring provides almost the identical fault tolerance as disk striping with parity (RAID-5). Mirrored disks however provide better write performance because parity information is not written. On the other hand, disk striping with parity (RAID 5) typically presents better read performance because read operations are distributed across multiple drives.
Disk operations can continue when one of the mirrored disks in a mirror set fails. Data in this case is written to the remaining disk in the mirror set. Mirrored sets are twice as pricy as RAID 0 because you essentially need twice as much storage space as the data you have. For each disk you want to mirror, you need a second disk of the exact same size because data is written to two locations. This in turn leads to mirrored volumes having a high overhead.
A variation of RAID 1 is duplexing. With duplexing, a separate disk controller is used for each mirrored disk. Duplexing can further improve performance and increase fault tolerance.

A RAID-5 volume cannot be used for the boot partition or system partition. This is due to the operating system needing to load initially to start the RAID-5 volume. RAID-5 is slower than RAID 1 because of its calculation of parity information. This makes RAID 5 processor intensive. RAID-5 volumes however need less space for redundant data than what RAID 1 needs. RAID-5 works where data availability is essential.
It is recommended that you use a hardware-based RAID-5 implementation in an Exchange Server 2003 organization.

How to implement a Striped Volume (RAID 0)

  1. Open the Disk Management console
  2. Right-click the unallocated space on the disk where you want to create the volume, and select New Volume to launch the New Volume Wizard. Click Next.
  3. Select Striped on the Select Volume Type window. Click Next.
  4. On the Select Disks window, select the disk(s) to include in the striped volume, and the amount of space to be used. Remember that the total space on any disk equals the smallest free space on any chosen disk Click Next
  5. On the Assign Drive Letter or Path window, assign a drive letter or mount the volume to an empty NTFS folder. Click Next
  6. On the Format Volume window, select a format (NTFS) for the volume, or select the Do not format this volume option. Click Next
  7. The Completing the New Volume Wizard window displays the options you have selected.
  8. Click Finish to create the striped volume.

How to implement a Mirrored Volume (RAID 1)

  1. Open the Disk Management console
  2. Right-click the volume you wish to mirror, and select Add mirror to open the Add Mirror window.
  3. Select the disk you want to use for a mirror. Click Add Mirror to create the mirror.

How to break a Mirrored Volume

  1. Open the Disk Management console
  2. Right-click the mirrored volume you wish to break, and select Break Mirror from the shortcut menu.
  3. A message asking you to verify your actions is displayed. The message also warns you that the volumes will not be fault tolerant if you continue.
  4. Click Yes to continue
  5. The mirror breaks. The next accessible drive letter is allocated to the volume located on the secondary disk.

How to implement a RAID 5 Volume

  1. Open the Disk Management console
  2. Right-click the unallocated space on the disk where you want to create the RAID-5 volume, and select New Volume to launch the New Volume Wizard. Click Next.
  3. Select RAID-5 on the Select Volume Type window. Click Next.
  4. On the Select Disks window, select the disk(s) to include in the volume, and the amount of space to be used. Click Next
  5. On the Assign Drive Letter or Path window, assign a drive letter or mount the volume to an empty NTFS folder. Click Next
  6. On the Format Volume window, select a format (NTFS) for the RAID-5 volume, or select the Do not format this volume option. Click Next
  7. The Completing the New Volume Wizard window displays the options you have selected.
  8. Click Finish to create the RAID-5 volume

Understanding How Transaction Logs Protect Data

When you store transaction log files separately to database files, the following benefits are achieved:


Each storage groups has its own transaction log file. The Information Store is arranged into storage groups. A storage group is a group of separate databases which have a common set of transaction log files. It is these storage groups that contain the mailbox stores, public stores, or both of these stores

From the transaction log file, the information is saved to the database file of the storage group. A checkpoint file indicates which transaction log entries have since been written to the database file. The information is not deleted from the transaction log file at this stage. It is only deleted when a full online backup of all the databases in the storage group is performed.

The concept of a soft recovery and hard recovery is illustrated below:

If the disk you are using for the transaction log files fails and the disk storing the databases are still online, no storage group data needs to be restored. You cannot though replay any transactions that are recorded to log files and not to the database files on disk.

Storage Technologies used with Exchange Server 2003

The different storage technologies that can be used with Exchange Server 2003 are listed below. The storage technology that you choose will be determined by the size of your Exchange Server 2003 organization

Managing Storage and Storage Groups

A few best practices for configuring storage groups and databases are summarized here:

Additional Storage groups would need to be created under the following conditions:

How to create storage groups

  1. Click Start, All Programs, Microsoft Exchange, and then select Exchange System Manager.
  2. Exchange System Manager opens.
  3. In the left pane, right-click the Exchange server and select New and then Storage Group from the shortcut menu.
  4. In the Properties dialog box which opens, in the Name textbox, provide a name for the new storage group. This is the name that will appear in Exchange System Manager and in the Active Directory Users And Computers management console.
  5. In the Transaction log location box, provide the location for storing the transaction logs. Click the Browse button to navigate to the location.
  6. In the System path location box, provide the location for storing temporary files. Click the Browse button to navigate to the location.
  7. In the Log file prefix box, the specific log file prefix is automatically assigned by the Exchange server.
  8. Enable the Zero out deleted database pages checkbox to have all deleted data removed from the drive.
  9. The Enable circular logging checkbox should not be enabled.
  10. Click OK.

How to add mailbox stores to a storage group

  1. Click Start, All Programs, Microsoft Exchange, and then select Exchange System Manager.
  2. Exchange System Manager opens.
  3. In the left pane, right-click the storage group container and select New and then Mailbox Store from the shortcut menu.
  4. On the General tab, provide the following information:
    • Database name
    • Default public store
    • Offline address list to use
    • Enable message archiving
    • Specify whether clients support S/MIME signatures.
    • Specify whether plain-text should be displayed in fixed-sized font.
  5. On the Database tab, provide the following information:
    • Provide the location for the EDB database.
    • Provide the location for the STM database.
  6. On the Limits tab, provide the following information:
    • Specify the message storage limit.
    • Specify the deleted items policy.
    • Specify the deleted mailbox policy.
  7. On the Full-Text Indexing tab, provide the following information:
    • Specify the frequency at which the full-text index is updated/rebuilt.
  8. On the Details tab, provide the following information:
    • Specify which configuration information needs to be manually inputted by administrators.
  9. On the Policies tab, provide the following information:
    • Specify the system mailbox store policies for the mailbox store.

How to delete mailbox stores

  1. Click Start, All Programs, Microsoft Exchange, and then select Exchange System Manager.
  2. Exchange System Manager opens next.
  3. Expand the Administrative Groups node, the administrative group, Servers node, the server, and then Storage Groups.
  4. Right-click the store that you want to remove and then click Delete.
  5. Click Yes to delete the store.
  6. Click OK.
  7. Proceed to manually delete the associated database files.

How to create a public store and associate it with the public folder tree

  1. Click Start, All Programs, Microsoft Exchange, and then select Exchange System Manager.
  2. Exchange System Manager opens.
  3. In the left pane, right-click the storage group and select New and then Public Store from the shortcut menu.
  4. Provide a name for the public store.
  5. Click the Browse button to associate the public store with the public folder tree.
  6. In the Available Public Folder Trees list, select the public folder tree.
  7. Click OK.
  8. Click OK to create the public store.
  9. Click Yes to mount the database

How to delete public folder stores

  1. Open Exchange System Manager.
  2. Expand the Administrative Groups node, the administrative group, Servers node, the server, and then Storage Groups.
  3. Right-click the public folder store and then select Dismount from the shortcut menu.
  4. Click Yes to dismount the store the public folder store.
  5. Right-click the public folder store and select Delete from the shortcut menu.
  6. Click Yes to delete the public folder store.
  7. A message appears, stating that another public folder store has to be selected for the server's system folders. Click OK.
  8. Select the appropriate public folder store for the system folders and click OK.
  9. Proceed to manually delete the database files.
  10. Right-click the mailbox store and select Dismount from the shortcut menu.
  11. Click Yes to dismount the store the mailbox store.
  12. Right-click the mailbox store and select Delete from the shortcut menu.
  13. Click Yes to delete mailbox store.
  14. Click OK.


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