text: **5.4.1 Migration policy**
  
  Migration policies and storage sets must be defined before you can define reports to Content 
  Manager OnDemand or load data into the system. Migration policies contain migration and 
  storage media characteristics for data that is archived by using Content Manager OnDemand. 
  The information is used by ASM to determine whether and when to move archived data 
  through a hierarchy of storage media, such as disk, optical, or tape. Each step in the 
  movement of data through this storage hierarchy is referred to as a*migration policy storage*
  *level*. Each migration policy must contain at least one storage level. Additional levels might be 
  defined to meet your storage and retrieval requirements. 
  
  The*Cache Only - Library Server*storage set is no longer created automatically with the 
  installation of Content Manager OnDemand for i. The “Cache Only” storage set is limiting 
  because you cannot add any storage levels to it. A better alternative is to define a disk pool 
  and create a migration policy instead. This approach provides the flexibility of adding 
  additional storage levels to the policy later. 
  
  When you create a migration policy, a storage set of the same name is automatically created 
  by Content Manager OnDemand. If you plan to keep all of your archives on disk, the best 
  approach is to create a disk pool and to create a migration policy that specifies “No Maximum” 
  for the duration level. Disk Storage Manager expires data and indexes whenever the number 
  of days is reached in the Life of Data and Indexes setting in the application group, or 
  whenever an expiration level in the migration policy is encountered, whichever comes first. If 
  no expiration level is in the migration policy, data is only expired according to the Life of Data 
  in the application group. 