Data Storage and Management

Remote Storage–Aware Products

Because Remote Storage manages data transparently for applications and users, there is no absolute requirement that other applications running on NTFS be Remote Storage–aware, that they contain specific code to recognize that Remote Storage is running. However, products that regularly open many files might cause a great deal of data to be recalled and reduce the benefits provided by Remote Storage. For best results, use Remote Storage-aware applications.

Important

Although the features included with Windows 2000 are Remote Storage–aware, many other applications are not and may result in time-outs or runaway recalls. In all cases, it is best to check with your ISV to see if they provide a version that is Remote Storage-aware.

Backup Programs

A Remote Storage–aware backup product must have the following abilities:

A guarantee that a full backup of the file is kept. The backup product must understand the difference between backing up the placeholder and the full data of the file, and must keep the full backup copy.
Backup a placeholder (reparse point) correctly.
Use of the FILE_FLAG_OPEN_BACKUP_SEMANTICS parameter when opening a file to back it up.
Understanding and proper use of FILE_FLAG_OPEN_NO_RECALL.

Backup applications that open placeholders to read and copy without using the FILE_FLAG_OPEN_BACKUP_SEMANTICS parameter cause the data for the file to be recalled. If these products are performing a full system backup, all placeholders are replaced with recalled data.

Remote Storage relies on the primary backup to protect placeholder data. The administrator must be aware of when placeholder backups occur. Specifically, if the backup rotations are used, the administrator must know when the primary backup databases contain a complete copy of the data and when they contain placeholder data.

Backup applications that are Backup-enabled protect placeholder data and do not cause recalls.

Antivirus Programs

Antivirus programs typically open files to check for infection by viruses. These products cause migrated data to be recalled. Remote Storage–aware antivirus programs can operate in one of the following manners:

Detect placeholders and skip the check on such files. This assumes that the data was checked by the scanner before being premigrated. This might be risky since Remote Storage manages the unnamed data stream and does not manage named data streams. Since data in remote storage remains unchanged, the check for a virus is unnecessary.
Open the file with the FILE_OPEN_NO_RECALL parameter. This allows the scanner to check the unnamed data stream using local storage without recalling the data. This assumes a linear search of the file data, which might not always be the case.
Don't update the last access date/time.

Document Management Programs

Many document management products open the data that they are managing, scan for key data, and then store references in additional files or alternate data streams leaving the original data unchanged. A document management product that is Remote Storage–aware opens placeholders with the FILE_OPEN_NO_RECALL parameter allowing the migrated unnamed data to be read but not recalled.

In addition, once the index files are generated, some document management products provide a file viewer much like Windows Explorer. As a Remote Storage-unaware product opens each file, it experiences synchronous recalls of each file and any associated delay. The Remote Storage-aware product indicates which files are migrated, and allows the user to issue asynchronous recalls of the data, while exhibiting improved performance.

Policies for managing files of the document management system exclude index files and other special files so they are quickly accessible to the document management system.

Note

The Indexing Service that is included with Windows 2000 is Remote Storage-aware.