Patent ID: 8578125

Claim:
A computer implemented method for allocating storage space in a storage group within a system managed storage environment, said storage group having a common area and a critical reserve area, said method comprising: reserving a predefined percentage of available storage space within said critical reserve area, wherein the critical reserve area stores critical data sets defined as critical in the storage group, wherein storage space in the critical reserve area storing critical data sets is not available storage space, and wherein the available storage space in the critical reserve area is available for storing, extending or allocating critical data sets; extending an existing data set or allocating a new data set in said critical reserve area; determining said storage group requires additional storage space in response to extending said existing data set or allocating said new data set in said critical reserve area; and allocating additional storage space to said storage group such that said predefined percentage of available storage space is maintained in said critical reserve area, wherein said predefined percentage of available space is determined by comparing available storage space within said critical reserve area to said storage space in said storage group.