An automated storage and retrieval system includes a first independently operable section having a first number of predetermined storage and retrieval transactions, and a second independently operable section in communication with the first independently operable section and having a second number of predetermined storage and retrieval transactions. The first and second independently operable sections are configured to provide a respective number of predetermined storage and retrieval transactions so that the first number of predetermined storage and retrieval transactions substantially matches the second number of predetermined storage and retrieval transactions.