data u201c 1 u201d frees data chunk a which is then de allocated so that it can be used by other applications or reused by journal 130 thereafter the new data labeled u201c 13 u201d is added to journal 130 which now stores data u201c 2 u201d to 13 u2033 fig3 shows that that data u201c 13 u201d is smaller than data u201c 1 u201d and as such the space required for storing data u201c 2 u201d to u201c 13 u201d is less than the space required for storing data u201c 1 u201d to u201c 12 u201d moreover journal 130 does not require as many data chunks at time 13 than it did at time 12 and non used resources are freed at time 13 for use by other applications specifically data chunks u201c b u201d u201c e u201d suffice for storing data u201c 2 u201d to u201c 13 u201d and data chunk u201c a u201d is freed up as shown in fig2 setting 204 enables an administrator to specify a maximum journal size when storage of new data would cause journal 130 to exceed its maximum size the oldest data is promoted to recovery disk 140 and removed from journal 130 until journal 130 is able to store the new data within its size limit in such case journal 130 may store less than 12 hours 39 worth of data i e less than the history specified by setting 203 reference is made to fig4 which is a simplified flowchart of a method 300 for a data.