EWF Volume Configuration
3/21/2011
When EWF is configured during the EWF installer process, it creates a small partition on the media. This partition is called the EWF volume. The EWF volume stores configuration information about the EWF-protected volumes on the device. This includes the number of protected volumes, protected volume sizes, and any of the overlay levels. Only one EWF volume is created on your device, regardless of how many disks are in the system.
The following list shows the EWF volume configuration requirements:
- For EWF RAM mode, the EWF volume is less than 64 KB. The EWF volume for RAM-based overlays stores additional boot commands that are applied when the system restarts, for example, EWF enable and disable.
- For EWF RAM Reg mode, the configuration information that is stored in the EWF volume is instead stored in the registry. RAM Reg modes are useful when you cannot create a new partition for the EWF volume.
During the EWF installer phase, EWFcfg.dll creates the EWF volume on your media. The EWF volume is created in one of the following two types of spaces on your media:
- Immediately after a primary partition
- Within the empty area in an extended partition
Note
If an extended partition is available on the system, EWF will always try to create the EWF volume within the empty area in the extended partition, even if there is additional free space at the end of the disk. If you have an extended partition, make sure that there is space within the partition for the EWF volume.
Note
Disk overlays must be disabled before re-deploying a pre-EWF installer runtime on the drive. If they are not disabled, EWF will be unable to delete and re-create these EWF Volumes during the EWF installer phase. If this step is missed then the error "missing or corrupted hal.dll" will be thrown during later starts of the system.
Make sure that your media can support creating an EWF volume. Some media, such as CompactFlash devices that are marked as removable, do not enable you to create new partitions. However, if the media is marked as fixed, you can create more than one partition on it. Some CompactFlash manufacturers supply utilities to mark the media as fixed.
Additionally, to prevent the operating system from changing drive letters that are assigned to existing volumes, use the following rule when you create the EWF volume: If an extended volume exists on the drive with sufficient space, the EWF volume is created as a logical volume. Otherwise, the EWF volume is created in a primary volume.
If you cannot create a new partition or change the partition structure of your media, consider implementing EWF RAM Reg mode. For more information, see EWF RAM Reg Mode.
The following list shows some common problems when configuring the EWF volume:
- There are already four primary partitions on the disk. Disks can have no more than four primary partitions.
- There is no space immediately after the primary partition.
- There is no space within the extended partition. The EWF volume cannot be created immediately after an extended partition.
- There is an existing EWF volume that was not deleted.