Windows Vista : Recovering Data (part 1) - Dealing with minor data loss

Vista offers support for data protection at three levels:

• Level 1 relates to minor data losses, for example, losing a single document or image on a PC.

• Level 2 relates to more comprehensive losses, but once again, losses focused on data and documents.

• Level 3 relates to major losses such as the loss of an entire system and its recovery.

The protection discussed in Level 1, Volume Shadow Copy, is available to three editions of Vista: Business, Enterprise, and Ultimate, and is an integral part of the operating system. The protection in Level 2 relies on the standard backup and restore tool contained within most editions of Windows Vista, Automatic Backup. Note that Automatic Backup is not included in the Starter Edition. The protection in Level 3 relies on Vista's Complete PC Backup tool which is also only available in the Business, Enterprise, or Ultimate editions of Vista.

1. Level 1: Dealing with minor data loss

The beauty of Level 1 protection within Vista is that it is focused on self-service and rarely involves the help desk after Vista users have learned how the feature works. With the release of Windows Server 2003, Microsoft introduced a new technology called the Volume Shadow Copy Service (VSS). Shadow copies or disk snapshots, as they are commonly referred to, are one of the major reasons why people implement shared storage. Shared storage systems — storage area networks (SAN) or network-attached storage (NAS) — include built-in technologies that support the capability of maintaining multiple concurrent copies of data. Among other things, these copies are used for backups (backing up a copy is much simpler than backing up live data because all files are closed) and restores (through special interfaces, users can even restore their own files). But the construction of these features is a complex task. Manufacturers have to basically design systems that will tell a running application to freeze all requests for data input and output for the time it takes to create the snapshot. This was a costly undertaking at best. Even worse, because most organizations implement heterogeneous solutions, they don't necessarily use the same drivers for backups as for undeletes. This is often a cause of instability.

By building snapshots into Windows, Microsoft has provided both VSS engines for its own applications (Exchange, Active Directory, and SQL Server) and a single standard set of APIs for application developers to write their own VSS engines, taking the onus away from the shared storage hardware manufacturer. In addition, VSS virtually eliminates the impact of data usage on backups and allows organizations to make data available in different formats for development and stress-testing purposes.

But, what's most impressive with VSS is what it can do for users. VSS automatically takes a snapshot of the files located in any shared folder where the service has been enabled. These snapshots include an image of the folder's contents at a given point in time. Depending on the space that you make available (each VSS snapshot is 100MB in size), you can have up to 64 different snapshots of a disk volume in Windows Server 2003 and much more in 2008. Because Microsoft has also made a client component of VSS — the Previous Versions client — available along with the VSS, users can have access to these snapshots. After it is implemented, users can recover almost any lost file by themselves, at the privacy of their own desk, without having to bother anyone and without the embarrassment of having to tell someone they've lost a file once again. The shadow copy service is designed to assist in the process of recovering previous versions of files without having to resort to backups. In this way, VSS is like an "undelete" utility.

In Windows Vista, VSS is on by default and takes snapshots of the entire contents of a disk on a regular basis. In addition, the snapshots have been reduced in size because only incremental changes are captured. Therefore, all data is protected while there is free space on a disk.

In Vista, the maximum size allocated to VSS is set to a value of 30 percent of free space or 15 percent of the overall size of the volume — whichever is less. This maximum size is static. It will not change when more or less free space is available, nor will it change after the size of the volume has been adjusted. However, you actually can manually adjust the size of this storage area by using the VSSAdmin tool from an elevated command prompt. For example, the command to increase the maximum storage size to 15GB on drive C: would be:

VSSAdmin Resize ShadowStorage /For=C: /On=C: /MaxSize=15GB

Use this command with care since in most cases, the default settings are appropriate.

To access VSS snapshots, you must use the Previous Versions tab on the Properties sheet of either a local disk, a local file folder, or a local file (see Figure 1). The Previous Versions client is installed by default in Vista and Windows Server 2008. However in XP and Windows Server 2003, you must deploy the Previous Versions client since it is not included in these operating systems. When you use the Previous Versions client, three options are available:

• Open: You can view the contents of the disk, folder, or file at the time of the snapshot.

• Copy: You can create a copy of the disk, folder, or file from the time of the snapshot.

• Restore: You can restore the copy of the disk, folder, or file to an alternate or the same location.

Users can access help information from directly within the Properties page by clicking on the How do I use previous versions? When users restore older versions of their documents, they must be careful to not overwrite the actual version unless of course, that is their goal.

This feature is a boon to you as system administrator because it cuts down your workload. All you really need to do is ensure that users are familiar with the Previous Versions tab in the Properties sheet of the items they create. Then, you may never have to address a lost document ever again.

Figure 1. Using Previous Versions to access backup copies of user data