Attempts to mirror the system disk fail in the following conditions:
 

• If Track Alignment is not enabled on the disk, the volume being mirrored covers the entire target disk.
   
• The Disable Track Alignment check box is selected when you use the Add Mirror wizard to add a disk for mirroring.
   

• Track Alignment is disabled from the Veritas Enterprise Administrator (VEA) Control Panel.
   

Usually, differences in the geometry between the original device and target device cause these errors. The geometries must be the same for mirroring boot devices. In this case, the command to disable Track Alignment is not sent correctly, causing the plex creation to occur at a point on the disk where it no longer fits in the available space.
 

As a workaround, set the following key in the registry:
 

HKEY_LOCAL_MACHINE\SOFTWARE\Veritas\VxSvc\CurrentVersion\VolumeManager\TrackAlignment Enable = 0
 

To resolve this issue, a private fix (File: vxconfig.dll, Version: 5.0.24.297) is available from Veritas Enterprise Technical Support. To obtain the private fix, contact Veritas Enterprise Technical Support and reference error message. A support representative will help troubleshoot this issue. If it is determined that the private fix addresses the problem, the support representative will help you obtain the private fix.
 

Note: This fix specifically addresses the aforementioned problem. It has not been fully tested and you should apply it in a test environment before you put it in production. If your systems are not critically impaired by this error, you should wait to install the private fix until the next scheduled maintenance release. Before you apply the private fix, you may need to upgrade your systems to the latest code base. The support representative can help you determine the best course of action. 
 

For more information, see the following TechNote:
 

www.symantec.com/docs/TECH54327

This error might occur when you try to mirror a boot disk that is not cylinder-aligned. It might also occur due to an operating system limitation for Logical Disk Manager (LDM) disks (native Windows disks).
 

Before you try to create a mirror, make sure that the source disk and target disk have similar geometry or Track Alignment. To determine whether the source disk and target disk have consistent geometry, gather the environmental information as described in the following procedure.
 

To determine whether the source disk and target disk have consistent geometry

1. Use the VEA GUI to gather information about each disk; right-click the device, choose Properties, and record the following information:
   
   
   • Port
      
   • Channel
      
   • Target
      
   • LUN
      
2. Use msinfo32 to record the geometry of the disks. Navigate to System Summary > Components > Storage > Disks.
    
3. For each Port, Channel, Target, and LUN, record the following information:
   
   
   • Total number of cylinders (C)
      
   • Tracks per cylinder (H)
      
   • Sector size (S)
      
   • Partition starting offset
      
4. Compare the geometries of both disks to check whether they match.
    
5. Determine whether the partitions are cylinder aligned.

For more information, see the following TechNote:
 

www.symantec.com/docs/TECH70438