Microsoft Corporation Staff, IT Professional Staff - Microsoft Windows 2000 Server Operations Guide
Remote Storage provides a single, system wide, Desired Free Space setting that can be applied to each managed volume. This setting establishes a threshold that triggers an automatic file truncation to free storage on the managed volume when free space is too low. The Desired Free Space setting can be specified by the administrator.
When you initially configure the Desired Free Space for a new managed volume, a reasonable predetermined default value is displayed. Separate from the default value, the system allows an administrator to set a new Desired Free Space for several different managed volumes all at the same time.
The single, system wide, Disk Management attribute is used for truncating premigrated files. The Disk Management attribute is not used to determine how much data is premigrated at a time.
Files are selected for Remote Storage based on the following criteria:
- Path name.
- File names, including wildcard characters in names.
- Inclusion or exclusion of specifications.
The following criteria can be applied to an entire volume but not at an individual file level:
- Last access date or inactivity period
- Owner
- File size
- System and hidden files
By default, the Windows 2000 system files or any files marked with the system attribute are excluded from premigration by Remote Storage.
The administrator uses these criteria to specify the eligible files. The inclusion and exclusion rules are applied such that the more specific a rule is to a file, the higher its priority. For example, the rules of "Exclude \*.*" and "Include \PROG\*.EXE" causes the file "\Prog\Test.exe" to be included and "\Test.exe" to be excluded.
The implementation of the selection criteria decision engine is extensible using a Component Object Model (COM) interface, so that it can be enhanced in the future and can allow user modifications.
Manage Files
The administrator schedules the management of files based on the specified file selection criteria. All files which meet the criteria are premigrated. The Desired Free Space is not used to determine how many files to premigrate. Premigrated files are tracked to allow rapid file truncation.
Even though Remote Storage changes the physical size of the file on local storage, the logical size and the date/time (create, last modified, last accessed) of the file remains unchanged.
Remove Volume From Management
This action removes the volume from management, and can optionally recall all files from Remote Storage.
Automatic File Truncation
Remote Storage initiates Automatic File Truncation whenever a managed volume's free space level is less than the Desired Free Space. Eligible premigrated files are truncated to free space on local storage. The premigrated files are quickly identified and truncated, based on the last access date. If the premigrated file has not been modified, then the file is truncated and becomes a placeholder. If the premigrated file has been modified, the file is not considered premigrated any longer and is returned to "normal file" status. Additionally, the capacity flow meter is decremented and the data for the premigrated file in remote storage is marked as "deleted" to facilitate space reclamation. Reclamation is the process of deleting from the Remote Storage media pool files that are no longer of interest or are no longer necessary, thereby making that storage space available for reuse.
The automatic file truncation continues until the free space on the volume is greater than the Desired Free Space.
Scheduled File Truncation
Scheduled File Truncation can be scheduled by the administrator to force the truncation of premigrated files to placeholders. The premigrated files that meet the selection criteria are truncated regardless of the free space level of the volume. Premigrated files are checked to make sure that they have not been modified since they were premigrated. If the 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 is marked as "deleted" to facilitate space reclamation.
This action allows proactive space management by an administrator. The action can be scheduled to reduce volume usage in advance of a known volume-intensive event, such as the installation of a very large application.
Validate Managed Files
Validate Managed Files can be scheduled by the administrator to validate placeholders and premigrated files that meet the selection criteria. Validation includes detecting placeholders moved among volumes, disconnected placeholders and modified premigrated files. Corrective actions are taken immediately to synchronize the placeholders and premigrated files with remote storage.
Validate Managed Files is used after restoring files to a volume or after disk errors on a volume. It can be scheduled to run on a regular basis (once a month) to validate the local storage and correct any inconsistencies.
Note
Recalls are logged in the Windows 2000 Event Log.
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