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Best practices for Shadow Copies of Shared Folders

Updated: January 21, 2005

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Best practices

Select a separate volume on another disk as the storage area for shadow copies.

  • Select a storage area on a volume that is not being shadow copied. Using a separate volume on another disk provides two advantages. First, it eliminates the possibility that high I/O load will cause shadow copies to be deleted. Second, this configuration provides better performance. This is the recommended configuration for heavily used file servers.

    For more information, see Change the settings for Shadow Copies of Shared Folders.

Consider how your clients will be using a shared resource before you enable Shadow Copies of Shared Folders and set scheduling options.

Do not enable shadow copies on volumes that use mount points.

  • The mounted drive will not be included when shadow copies are taken. Enable shadow copies only on volumes without mount points or when you do not want the shared resources on the mounted volume to be shadow copied.

    For more information, see Using NTFS mounted drives.

Do not enable shadow copies on dual-booting computers.

  • If you have enabled dual-booting into previous versions of Windows (such as Windows NT 4.0), the shadow copies which persist while restarting the older version might be corrupted and unusable when the computer is started again with Windows Server 2003 .

Use Backup to perform regular backups of your file server.

  • Shadow Copies of Shared Folders is not a replacement for performing regular backups. Use a backup utility in coordination with Shadow Copies of Shared Folders as your best preparation for restoring.

    For more information, see Backup.

Do not schedule copies to occur more often than once per hour.

  • The default schedule is 7:00 A.M. and 12:00 noon, Monday through Friday. If you decide that you need copies to be taken more often, verify that you have allotted enough storage space and that you do not take copies so often that server performance degrades. There is also an upper limit of 64 copies per volume that can be stored before the oldest copy is deleted. If shadow copies are taken too often, this limit might be reached very quickly, and older copies could be lost at a rapid rate.

    For more information, see Defining a schedule for shadow copies.

Before deleting a volume that is being shadow copied, delete the scheduled task for creating shadow copies.

  • If the volume is deleted without deleting the shadow copy task, the scheduled task will fail and an Event ID: 7001 error will be written to the event log. Delete the task before deleting the volume to avoid filling the event log with these errors.

    For more information, see Change the schedule for creating shadow copies.

Use an allocation unit size of 16 kilobytes (KB) or larger when formatting a source volume on which Shadow Copies of Shared Folders will be enabled.

  • If you plan to defragment the source volume on which Shadow Copies of Shared Folders is enabled, it is recommended that you set the cluster allocation unit size to be 16 KB or larger when you initially format the source volume. If you do not, the number of changes caused by defragmentation can cause previous versions of files to be deleted.

  • If you require NTFS file compression on the source volume, you cannot use an allocation unit size larger than 4 KB. In this case, when you defragment a volume that is very fragmented, you may lose older shadow copies faster than expected.

    For more information about formatting a volume, see Format a basic volume.

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