What Is Remote Storage?
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
What Is Remote Storage?
In this section
Common Scenarios for Remote Storage
Remote Storage Dependencies on or Interactions with Other Technologies
Remote Storage Logical Diagrams
Related Information
You can use Remote Storage to extend disk space on your server without adding more hard disks. Remote Storage automatically copies eligible files on your local volumes to a library of magnetic tapes or magneto-optical disks. Remote Storage then monitors the amount of space that is available on your local volumes.
When the amount of available space on a local volume falls below the level that you designate, Remote Storage automatically removes the content (data) from a sufficient number of eligible (or premigrated) files and migrates this content to an attached storage device, thus freeing up disk space on the volume. When data is removed from a file, the logical size of the file remains the same, and to the user, the file appears unchanged, but the physical size of the file is reduced to 1 KB. Content in other eligible files is not removed until more disk space is needed. When you need to open a file whose data has been removed, the data is automatically recalled from remote storage. To find more information about these processes, see “Remote Storage Logical Diagrams” in this section. See also “Remote Storage Terms and Definitions” and “Remote Storage Processes and Interactions” in “How Remote Storage Works.”
Remote Storage runs on Windows Server 2003, Enterprise Edition; Windows Server 2003, Datacenter Edition; and the 64-bit versions of these operating systems. Remote Storage is also available on Windows 2000 Server. However, Remote Storage is not installed by default. To install Remote Storage, you can select Remote Storage during Setup, or you can later manually install Remote Storage through Add or Remove Programs in Control Panel. You can only use Remote Storage to manage NTFS volumes.
Levels of data storage
Remote Storage data storage is hierarchical, with two defined levels. The upper level, called local storage, includes the NTFS disk volumes of the computer running Remote Storage. The lower level, called remote storage, includes the automated media library or stand-alone tape or disk drive that is connected to the server.
Remote Storage supports all SCSI-class 4-mm tape, 8-mm tape, digital linear tape (DLT), and magneto-optical devices that are supported by Removable Storage. (To find more information about Removable Storage, see “What Is Removable Storage?.” To find more information about the relationship between Remote Storage and Removable Storage, see “Remote Storage Processes and Interactions” in “How Remote Storage Works.”) Remote Storage does not support quarter-inch cartridge (QIC) tape libraries, rewritable compact disks (CD-RWs), or rewritable DVDs (DVD-RWs).
Retrieval of stored files
When you need to access a file on a volume managed by Remote Storage, you simply open the file as usual. If the data for the file is no longer on your local volume, Remote Storage recalls the data from a media library. Because this can take more time than usual, Remote Storage removes the data only from those files on your local volumes that you are least likely to need, based on criteria that you set.
Coordination with other tools
Remote Storage uses Removable Storage to access the applicable tapes that are contained in libraries. Remote Storage also works with Backup for data recovery, and with Task Scheduler to schedule file copy operations. For information about Removable Storage, see “Removable Storage Technical Reference.” For information about Backup, see “Backup Technical Reference.”
Remote Storage also provides certain data-recovery features, including the ability to generate multiple copies of data in remote storage.
Business Benefits
Remote Storage provides several significant business benefits, including the following:
A low-cost solution for archiving files that are seldom accessed, but should still be available.
A low-cost solution that enables virtual expansion of local storage space.
Transparent automatic access to data in remote storage.
Automation of the labor-intensive overhead associated with daily manual data-management operations.
Centralized sharing of remote storage devices for multiple volumes.
Note
- Using Remote Storage to copy files to remote storage is not the same as backing up your files. You should follow a regular schedule of data backups, including backing up the contents of the local volumes that Remote Storage manages. You should also back up the Remote Storage database and other program files that are located in the System32\RemoteStorage folder.
Note
Do not create File Replication service (FRS) replica sets on a volume that is managed by Remote Storage. In addition, do not add a volume to Remote Storage that contains directories that are part of an FRS replica set. Otherwise, you might severely impact system performance and possibly cause data loss within your media library.
FRS might need to periodically read every file in the replica set to send the file contents to another computer. This causes FRS to recall all files that Remote Storage has sent to secondary storage, which might take a long time (hours or days). If you use tape for your secondary storage, remember FRS recalls files in directory order rather than media order, so the excessive number of tape seeks performed by FRS will likely ruin the tapes and cause data loss.
Common Scenarios for Remote Storage
Remote Storage is especially useful in the following scenarios.
(To find more information about the terms used in these scenarios, see “Remote Storage Terms and Definitions” in “How Remote Storage Works.” See also “Remote Storage Processes and Interactions” in the same topic.)
Conserving disk space on managed volumes
In this scenario, you want to ensure that disk space on the managed volume where your system files are located does not fall below a certain level because you are concerned that operating system efficiency will be severely compromised if this is allowed to happen.
Remote Storage initiates Automatic File Truncation whenever the level of free space on a managed volume becomes less than the specified Desired Free Space. Eligible premigrated files are truncated in order to create additional free space on this volume. The premigrated files are quickly identified and truncated, based on the last access date, and are moved to an attached storage device from which they can later be retrieved if necessary. Placeholders for these files are created and reside in local storage, and the files themselves appear unchanged to the user. Automatic File Truncation continues until the free space on the volume is greater than the Desired Free Space.
To find more information about this process, see “Remote Storage Logical Diagrams” later in this section.
Extending disk space on managed volumes
In this scenario, you want to make additional space available for new, more frequently accessed files, while retaining older, less frequently accessed files that you might need to access some time in the future.
By using Scheduled File Truncation, you can force the truncation of premigrated files. The premigrated files that meet the selection criteria are truncated, regardless of the available space on the managed volume. Premigrated files are checked to make sure that they have not been modified since they were premigrated. If a premigrated file has been modified, then the file is not considered premigrated and the file is returned to normal file status. Additionally, the data for the premigrated file in remote storage (called the “unnamed data attribute”) is marked as “deleted” to facilitate the reclaiming of space on the device.
With Scheduled File Truncation, you can manage disk space proactively. The action can be scheduled to reduce volume usage before a known volume-intensive event, such as the installation of a very large application.
To find more information about this process, see “Remote Storage Logical Diagrams” later in this section.
Generating multiple media copies of removable media
In this scenario, you want ensure that there exists one or more copies of your migrated files on different media in case the original storage medium (disk or tape) becomes unusable.
Media in remote storage are copied to protect data. Copies are updated at the same time as the original media are updated to ensure that a current copy of data is available.
Media copies are replicas that can be substituted for the original media. Data is migrated only to the original media, but can be recalled from either an original or a copy.
Copies are made before the original media are completely filled and are updated as the original is updated. When a media copy is complete, it can be removed from the library located with other media in the copy set, and a new media copy is started.
Remote Storage creates media copies only if a library has two or more available drives. Other media, for which copies cannot be made, must be protected by different means, such as strict physical or environmental safeguards. To replace an original with a copy, you must manually perform the action. You should uniquely identify media copies in order to avoid confusion among different versions.
When a media copy is used to replace damaged or lost remote storage media, Remote Storage automatically copies the media again to ensure a complete set of copies.
Replacing damaged removable media while Remote Storage is running
In this scenario, you want to ensure that when you replace a copy of your migrated files with another copy of the same files, Remote Storage will, at the same time, automatically generate additional copies on different media.
When a media copy is used to replace damaged or lost remote storage media, Remote Storage automatically copies the media again to ensure a complete set of copies.
Remote Storage creates media copies only if a library has two or more available drives. Other media, for which copies cannot be made, must be protected by different means, such as strict physical or environmental security. To replace an original with a copy, you must manually perform the action. You should uniquely identify media copies in order to avoid confusion among different versions.
Recovering from loss of Remote Storage metadata
In this scenario, you want to ensure that you can retrieve any metadata associated with your Remote Storage files.
Remote Storage metadata exists in files that can be protected by the primary backup system (Backup) for Windows Server 2003, Enterprise Edition and Windows Server 2003, Datacenter Edition. Windows Server 2003 file security ensures that only the account used by Remote Storage has access to the metadata. Therefore, the administrator must assign appropriate user rights to this account so that only certain individuals (or groups) have access to this metadata. Otherwise, the metadata might be at risk, and if deleted, would no longer be retrievable.
Selecting the Appropriate Storage Medium: Two Different Scenarios
As part of deciding whether or not to use Remote Storage, it is important to select the appropriate storage medium. Remote Storage supports magnetic tape and optical discs as media.
The following section compares the advantages and disadvantages of using magnetic tape or optical discs for your remote storage media and then presents two different scenarios as examples of the decision-making process.
Advantages of Using Magnetic Tape
The advantages of using magnetic tape include:
Magnetic tape drives and media are less expensive than optical disc changers and media.
Magnetic tape drives and media take up less room per megabyte than optical changers and associated media.
Magnetic tapes are available in several different sizes.
Disadvantages of Using Magnetic Tape
The disadvantages of using magnetic tape include:
A magnetic tape changer takes longer to recall files that have been migrated to Remote Storage. (Magnetic tapes are sequential access media. Depending on the location of a file on the tape, it can take longer to recall a file.)
The shelf life of magnetic tapes is substantially shorter than that of optical discs.
Files in Remote Storage cannot be recalled while a media copy to magnetic tape is in progress.
Magnetic tapes require the following special environmental considerations:
Backup media lasts longer in cool, humidity-controlled locations.
Backup media must be stored in an area free of magnetic fields, such as those near the backs of computer terminals and analog telephone equipment.
Advantages of Using Optical Media
The advantages of using optical media include:
Optical disc changers recall files from Remote Storage faster than magnetic tape changers. (Optical discs are random access media. Regardless of where the files exist on a disc, discs enable faster seek times while recalling files.)
Optical media has a longer shelf life than magnetic tape.
Files in Remote Storage can be recalled while a media copy is in progress.
Optical discs do not require special environmental considerations.
Disadvantages of Using Optical Media
The disadvantages of optical media include:
Optical disc changers and media are more expensive than magnetic tape drives and media.
Optical disc changers and media take up more room per megabyte than tape changers and associated media.
Optical media are available in fewer different sizes.
The following scenarios provide examples of when tape or optical media might be appropriate for an organization.
Magnetic Tape Scenario
You are a network administrator at an urgent care medical facility. One of your responsibilities is to maintain the health records of patients who are treated in your facility. A typical patient is treated and released without the need for follow-up care. The patient files are not likely to be recalled from Remote Storage, and recalling these files quickly is not necessary. You decide to use magnetic tape as the most cost-effective storage solution for your organization.
Optical Disc Scenario
Your role in the IT department of a large insurance company is to archive vast amounts of customer information. It is extremely important that this information be readily accessible and that the media on which the information is stored have as long a shelf life as possible. You decide to use optical media as the most practical storage solution for your organization.
Remote Storage Dependencies on or Interactions with Other Technologies
Remote Storage depends on, or interacts with, the following technologies:
Microsoft Management Console
Removable Storage
Backup (or similar, non-Microsoft data-management programs)
Win32 tape and disk management APIs
Media libraries
The registry
Event Viewer
Windows Explorer
Windows security
NTFS
Task Scheduler
Microsoft Systems Management Server (SMS)
Active Directory
To find more information about this topic, see “Remote Storage Architecture” in “How Remote Storage Works.”
Remote Storage Logical Diagrams
The following figures show how files are migrated to, and later recalled from, remote storage.
In the first figure, files on a user’s hard drive are premigrated when their unnamed data attributes are copied to an attached storage device. These files are now eligible for truncation.
Remote Storage Logical Diagram - Files Are Premigrated
.gif "Files Are Premigrated")
In the second figure, the files that have been premigrated are automatically truncated and then migrated to an attached storage device when the level of available space on the hard drive falls below the Desired Free Space.
Remote Storage Logical Diagram - Files Are Truncated and Migrated
.gif "Files Are Truncated and Migrated")
In the third figure, the files are recalled from the attached storage device when the user accesses the files on the hard drive. The files on the hard drive appear unchanged to the user, even though the data was removed during Step 2.
.gif "User Recalls Migrated Files")
Related Information
The following resources contain additional information that is relevant to this section.
Resource Kit Tools Help in the Tools and Settings Collection.
Command-Line References in the Tools and Settings Collection.