1) Seal MPs where you store SLOs
2) Store SLOs separately (in separate MPs)
3) Increase the number of versions of the sealed MP DW will preserve. To do this, run the following SQL Query on the SCOM Data Warehouse Database (default: OperationsManagerDW):
UPDATE [MaintenanceSetting] SET [NonSealedManagementPackMaxVersionCount] = 8
NOTE: 8 is just an example number. DO NOT set the number too high. We advise against setting this to a larger number than 10. You should try a smaller number until it fits for your environment.