Tape Capacity Differences Prevent Remote Storage from Making Media Copies (266011)

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256986 Description of the Microsoft Windows Registry

SYMPTOMS

When you attempt to make media copies of a Remote Storage Service (RSS) master media, you may receive the following administrator alert message:

[Messenger Service]
"Remote Storage cannot find a unit of free media of sufficient capacity. Please add a unit of [tape] media with a nominal (uncompressed) capacity of at least n.n GB."

This message is also contained in Removable Storage Manager (RSM) "Operator Requests" as an Inject Media operation. This occurs even if you have free media with what should be sufficient capacity in the free media pool or RSS media pool.

Note: The operator request has a life span of one hour. If the request goes unanswered, after one hour it is logged as "refused," and then the request is cancelled and reissued automatically.

CAUSE

When tapes are manufactured, the actual capacity and tolerance of each tape may vary plus or minus several or even hundreds of megabytes from its stated capacity, depending on the total stated capacity of the media. RSS is supposed to compensate for the slight differences in tape capacities by keeping a 5 percent tolerance zone of free space at the end of the tape. Under certain circumstances, RSS may fill the media master tape almost to 100 percent capacity.

To see if this is the case, look at the Free Space column under the Remote Storage Media icon. Instead of 5 percent free, there may be only a few megabytes of capacity left on the tape. Consequently, if RSM cannot find media of equal or greater capacity, RSS cannot perform the media copy operation.

RESOLUTION

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To work around the problem, use one of the following methods.

Method 1

Use larger capacity tape media (if available for your tape library) for media copy operations only to ensure that the copy media is always larger than the media master.

Method 2

RSM allows copy media that is up to 2 percent smaller than the original master media to be used for a copy. This default of 2 percent is configurable in the registry. However, because RSS may fill the master media completely, allowing RSM to pick a piece of media that is too small might cause the copy job to fail.

Use Registry Editor to define the new tolerance percentage.

Run Regedt32.exe to start Registry Editor.
Navigate to the following key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Remote_Storage_Subsystem\Parameters
Highlight the Parameters key, and then choose Add Value from the Edit menu.
Enter the value name MediaCopyTolerance using Data Type of REG_SZ.

Enter the value n (where n is between 2 and 5). By default, copy media capacity is allowed to be 2 percent smaller than the master, but it is strongly recommended that you do not use a value over 5.
Quit Registry Editor.
Shut down, and then restart the computer so that RSM can initialize using the new MediaCopyTolerance value.

Try to make another media copy, or complete the operator request if it is still present; see if RSM accepts, and then mount the free media and continue with the media copy.

Note Make sure that the tape device driver and firmware are updated to the latest versions.

MORE INFORMATION

You may experience media copy failures because the media copy (destination) tape capacity is too small. Should this occur, the following event message is posted in the Remote Storage Service log:

Event Type: Error
Event Source: Remote Storage
Event Category: Engine
Event ID: 2003
Description: An error occurred while Remote Storage was attempting to update copy set X for media RS-MYSERVER-1.
Physical end of the media has been reached. (0x810b0013).

This is an indication that the MediaCopyTolerance registry value is too large and should be reduced.

An indicator that a media copy operation has been unsuccessful is an incorrect date and time stamp in place of the copy version information. If an operation is unsuccessful, RSS does not update the stamp:

When a media copy job is performed for the first time on the media, the "last copy time" is initialized with zero.
Remote storage allocates the copy media. If the copy operation stops before completion, the copy time is not updated. Because it is the first time the job has been run, the time remains zero.
The user interface (UI) displays "zero time" as January 1, 1970 0:00 Greenwich mean time, which is zero for Microsoft Foundation Classes absolute time (CTime) class (which translates to December 31, 1969 16:00 Pacific time if the clock in your computer is set to Pacific time).

After a successful copy media operation, the copy version date and time will reflect the current master version date and time. If you perform a migrate operation to copy more files to the master media, the master version is more recent and the copy is no longer current. The copy version date and time will reflect the older version of the master from which you made the copy.

For additional information about creating media copies, click the following article number to view the article in the Microsoft Knowledge Base:

265487 How Remote Storage Creates Media Copies