ENTERPRISE

Exchange Server 2010 : Maintaining Reliability and Availability - Back Up Exchange

5/24/2011 3:42:51 PM
At the heart of Exchange lies the ability to retain and allow access to vast amounts of data. Emails get populated in user's mailboxes from both internal and external sources. Often, once an email is received from someone, the only copy exists in the recipient's mailbox. Inadvertently losing this data and not being able to recover it can cause many problems.

It's difficult to overstress the benefits of keeping backups of data for Exchange. Traditionally, it was important to keep backups not only for data recovery purposes, but also for the purpose of truncating transaction logs. If you went multiple days without a backup, you risked the possibility of transaction logs filling up the disk volume, which forced Exchange to shut down the access to those databases.

However, backup technology has evolved over the years and Exchange has kept pace with the changes in backup technology. With technology like volume snapshots, it no longer takes hours upon hours to back up databases in Exchange. In some instances in Exchange Server 2010, it may be wise to eliminate backups altogether and instead rely on data replication to meet your recovery goals.

1. Develop an Effective Backup Strategy

At the cornerstone of meeting your data recovery goals is the development of an effective backup strategy. Without a backup strategy in place, you won't understand what your backup requirements are or whether the backup tool you use fits those requirements. It's also important to lay out your recovery plans. When a disaster strikes and you have a limited time to react, it's important to be able to pull out your recovery plan and follow it with the assurance that it works.

To determine what your backup requirements are, you must first understand why you are backing up the data. Then you can determine what your goals are for recovery. And finally, you can decide how often you want to perform backups.

1.1. Understand the Reasons for Backups

There are many reasons that an organization would want to perform backups, such as the following:

  • To have the ability to restore an entire server from scratch

  • To have the capability of restoring a failed or damaged database

  • To maintain a copy of the mailboxes of people who recently left the organization

  • To recover messages that a user has deleted

You will need to determine which of these scenarios apply to your goals for recovery. For example, you may not want the capability to restore an entire server from backup if you are using DAGs for database availability. In this case, it might not be a big deal to install a new Mailbox server with a different name and enable a database copy on the server.

1.2. Determine Recoverability Goals

After you have an understanding of why you want to perform backups, you can start determining your goals for recovery. You will want to consider each scenario for which that the backup is maintained and determine how long you want to retain the data and how quickly you want to be able to restore the data. You will use these metrics to determine what your backup architecture will be. For example, you may decide to keep backups on site instead of shipping them offsite in order to meet your data recovery time objective.

Each scenario may have different recovery objectives. Table 1 demonstrates how recoverability goals can be different for each scenario.

Table 1. How Recoverability Goals Differ Between Scenarios
ScenarioData Retention GoalData Restoration Goal
Database becomes corruptRestored database must not be older than 1 dayMust have dial-tone service up within 1 hour and the database must be restored within 8 hours
Mailbox accidently deleted by administratorRestored data must be less than 3 days oldMailbox must be restored within 1 hour
User needs to recover a message that was deleted 30 days agoMust be able to restore messages for up to 60 daysMessage must be restored within 1 business day

The key is to determine the minimum and maximum lengths of time that backed up data must be kept and select a backup methodology that allows you to restore the data within your target restoration goal.

1.3. Decide on a Backup Schedule

When you know how frequently you must back up the data, you can more easily determine what your backup schedule should be. In keeping with the example described in Table 1, you can see that restored databases must not be older than one day. This means that databases need to be backed up daily.

Also from Table 1, you can see that the scenario requires you to be able to restore messages for up to 60 days. Therefore, you know that you must be able to keep 60 days of backups in order to meet this goal.

1.4. Consider Backup Alternatives in Exchange

It is worth mentioning the new school of thought about backups in Exchange Server 2010. The idea is that in some situations, backups may not need to be kept at all. In fact, Microsoft decided to use this approach when deploying Exchange Server 2010 internally and completely eliminated the cost of maintaining data backups.

The idea of using replication as an alternative to backups is met with mixed emotions by different people. In many organizations, backups are performed in a certain manner because that's the way they've always done it. In many ways, this consideration is less of a technical consideration and more of a psychological one. An environment where replication is used for backups is not the right solution for everyone. However, the following capabilities in Exchange Server 2010 fill in the gaps that backups have traditionally been used to fill.


Server Failure

Add mailbox servers to a DAG and replicate copies of the databases to other servers.


Disk Failure

Place each database and transaction log folder on the same physical disk. Add the mailbox server to a DAG and ensure that at least three copies of the database exist in the DAG.


Database Corruption

Enable transaction log replay lag on the database copies in the DAG. This allows you to recover the database without the transaction log that caused the corruption.


Single Message Recovery

Exchange now has single-item recovery built in. You just need to enable it and specify how long you want to keep deleted messages for.


Mailbox Recovery

Exchange maintains a copy of deleted mailboxes for 30 days by default. This time is adjustable if you need to retain deleted mailboxes for longer periods of time.


Site Failure

Instead of using off-site backups, consider stretching your DAG across sites for site resiliency.

If you decide to implement database replication as a replacement for traditional backups, you should keep the following recommendations in mind:

  • Make sure that you have at least three copies of your databases replicated inside a DAG.

  • Implement lagged database copies if you frequently experience logical corruption of your mailboxes due to third-party applications.

  • Enable circular logging on your databases to ensure that transaction logs are truncated.

  • Make sure that you implement your architecture in a way that allows you to sleep peacefully at night. If you're constantly worried that you may lose all three copies of the database, implement additional database copies and maybe even place one or two of the copies in a different site.

2.2. Perform Backups with the Windows Server Backup Tool

When the Windows Server Backup Tool came out in Windows Server 2008, support for native Exchange backups was removed. This capability is now back. Exchange Server 2010 installs a service called Microsoft Exchange Server Extension for Windows Server Backup. This service provides Windows Server Backup with the ability to make Volume Shadow Copy backups that are Exchange-aware. Having this capability out of the box in Windows Server 2008 is a good thing, but there are limitations to using Windows Server Backup for Exchange backups:

  • Only full volumes can be backed up. You cannot make a backup of the Exchange database and transaction log files independently. Instead, the Exchange data is backed up when you back up the volume that the data lives on. Because of this, both the transaction logs and the database file for a given mailbox server database need to be available in the same backup set in order to restore the data.

  • Backups cannot be taken remotely. Backups must be initiated on the server either manually or via a scheduled task.

  • In order for transaction logs to be truncated, only full backups must be taken.

  • Single databases cannot be restored. When you perform a restore, all the databases that were backed up in the backup job are restored.

  • You can only back up active copies of the databases. Passive copies cannot be backed up with Windows Server Backup.

2.2.1. Install Windows Server Backup

Windows Server Backup exists as an installable feature in Windows Server 2008. To install Windows Server Backup and the command-line backup tools, run the following command from a command prompt:

ServerManagerCmd -i Backup-Features

2.2. Perform a One-Time Manual Backup

To perform a one-time backup manually with Windows Server Backup, use the following steps. These steps may vary slightly if you are using Windows Server 2008 to perform the backup.

  1. Open Windows Server Backup by choosing Start => All Programs => Administrative Tools => Windows Server Backup.

  2. In the Actions pane on the right, select the task Backup Once. This launches the Backup Once wizard.

  3. On the Backup Options screen of the wizard, select Different Options and click the Next button.

  4. On the Select Backup Configuration screen, select Full Server to back up the entire server or select Custom to choose which volumes you want to back up.

    In this example, we're only going to back up the volumes that contain Exchange databases. So choose Custom and click Next.

  5. On the Select Items For Backup screen, click the Add Items button to add a volume to the backup list. This opens the Select Items dialog box.

    In the Select Items dialog box, check the box next to the volumes that contain the databases that you want to back up. After you have chosen your volumes, click OK to close the dialog box. Then click the Advanced Settings button.

  6. In the Advanced Settings dialog box, select the VSS Settings tab. Choose the option VSS Full Backup and click OK. Only full VSS backups are supported when you are using the Windows Server Backup tool to back up Exchange data.

    Back in the Backup Once wizard, click Next.

  7. On the Specify Destination Type screen, select Local Drives to store the backup on a local disk or select Remote Shared Folder to store the backup on a network share.

    In this example, we are going to store the backup on a local disk. Select Local Drives and click Next.

  8. On the Select Backup Destination screen, select the volume that you want to store the backup on from the Backup Destination drop-down list. Only volumes that have enough free space are displayed in the list.

    Click Next to continue.

  9. At the Confirmation screen, verify that the backup settings are accurate and click the Backup button to begin the backup.

    While the backup is running, you can safely close the Backup Once wizard by clicking the Close button. This does not stop the backup.

  10. When the backup is complete, click Close to close the Backup Once wizard if you haven't done so already.

2.3. Perform Automated Backups

In addition to performing manual backups, you can set up scheduled backups that occur in an automated fashion through Windows Server Backup. To set up scheduled automated backups, use the following steps. These steps may vary slightly if you are backing up a server that is using Windows Server 2008 R2.

  1. Open Windows Server Backup by choosing Start => All Programs => Administrative Tools => Windows Server Backup.

  2. In the Actions pane on the right, select the task Backup Schedule. This launches the Backup Schedule wizard.

  3. On the Getting Started screen of the wizard, click Next.

  4. In the Select Backup Configuration dialog box, select Full Server to back up the entire server or select Custom to choose which volumes you want to back up.

    In this example, we're only going to back up the volumes that contain Exchange databases. So choose Custom and click Next.

  5. On the Select Backup Items screen, the list of volumes on the server is presented. Check the box next to the volumes that contain the databases that you want to back up. Then click Next to continue.

  6. On the Specify Backup Time screen, select Once A Day to back up Exchange only one time each day. From the Select Time Of Day drop-down list, select the time that you want to start the backups.

    You also have the option of selecting More Than Once A Day if you want to back up Exchange multiple times throughout the day.

    After you have selected your backup schedule, click Next.

  7. On the Select Destination Disk screen, place a check mark next to the disks that you want to store your backups on. If you want to use disks that are local to the server, click the Show All Available Disks button. By default, only external disks are shown. Click Next to continue.

    Note that the disk you selected will be formatted and dedicated for storing backups. If you see a dialog box that warns you about this, click the Yes button to continue. You will lose the data on this disk if you click Yes, so ensure that you really want to dedicate the disk for backups.

  8. At the Label Destination Disk screen, view the labels that are designated for your backup disks. You can physically write this name on the disk or record it on paper to ensure that you know what disk corresponds to which label. Click Next to continue.

  9. At the Confirmation screen, verify that the backup settings are accurate and click the Finish button to complete the process and prepare your disks.

  10. At the Summary screen, view the results of the scheduled backup and click Close to close the Backup Schedule wizard. If you previously had a mounted volume and used that disk as your backup location, the volume will no longer be available.

Other  
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  •  Exchange Server 2010 : Utilize the Availability Options for Servers Based on Role (part 2) - Increase Mailbox Database Availability
  •  Exchange Server 2010 : Utilize the Availability Options for Servers Based on Role (part 1) - Load-Balance Client Access Servers
  •  Exchange Server 2010 : Track Exchange Performance (part 2) - Test the Performance Limitations in a Lab
  •  Exchange Server 2010 : Track Exchange Performance (part 1) - Use the Performance Tools Available
  •  Exchange Server 2010 : Keep Exchange Healthy (part 2) - Verify Exchange Server Health
  •  Exchange Server 2010 : Keep Exchange Healthy (part 1) - Ensure That Mail Flows Freely
  •  Programming WCF Services : Queued Services - Instance Management
  •  Programming WCF Services : Queued Services - Transactions
  •  Exchange Server 2010 : Implementing Client Access and Hub Transport Servers - Test Cmdlets for CAS and Hub Transport Servers
  •  Exchange Server 2010 : Implementing Client Access and Hub Transport Servers - Installing the Hub Transport Server
  •  Exchange Server 2010 : Implementing Client Access and Hub Transport Servers - Transport Pipeline
  •  Exchange Server 2010 : Implementing Client Access and Hub Transport Servers - Understanding the Hub Transport Server
  •  Implementing Client Access and Hub Transport Servers : Installing the Client Access Server
  •  Implementing Client Access and Hub Transport Servers : Understanding the Client Access Server (part 2)
  •  Implementing Client Access and Hub Transport Servers : Understanding the Client Access Server (part 1)
  •  SharePoint 2010 : Implementing and Managing In Place Records
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