Determine the level of protection that you want

The level of mirrored protection determines whether the system keeps running when different levels of hardware fail. The level of protection is the amount of duplicate disk-related hardware that you have. The more mirrored pairs that have higher levels of protection, the more often your system will be usable when disk related hardware fails. You may decide that a lower level of protection is more cost effective for your system than a higher level.

When determining what level of protection is adequate, you should consider the relative advantages of each level of protection with respect to the following:

• The ability to keep the system operational during a disk-related hardware failure.
• The ability to perform maintenance concurrently with system operations. To minimize the time that a mirrored pair is unprotected after a failure, you may want to repair failed hardware while the system is operating.

• Details: Levels of protection
  
• Disk-unit level protection
  
• Input/output bus level protection
  
• Input/output adapter level protection
  
• Input/output processor level protection
  
• Bus-level protection
  
• Expansion-unit level protection
  
• Ring-level protection