In the prior art several types of mass storage systems are known, in which the high capacity storage means consist of physical libraries of magnetic storage media, called cartridges, handled by robots. These physical libraries comprise a plurality of cartridges in which data is written and read by means of at least one reader which individually accesses, via robotics, each of these cartridges when a request for writing or reading is transmitted by one of the computer platforms to the mass storage system. However, these known prior art solutions have the major disadvantages of being relatively slow, and of rapidly becoming saturated when numerous requests for access to the physical libraries are sent by the platforms. Mass storage systems are also known in the prior art which comprise large size memory means, called cache, forming a buffer between the computer platforms and the physical libraries. These large-size memory means consist, for example, of a plurality of hard disks in which the data sent or consulted by the platforms can be temporarily stored, to facilitate platform accessing to data while the system performs necessary operations within the physical library of physical cartridges. These mass storage systems known in the prior art therefore allow data to be stored temporarily in large-size memory means, to enable access thereto by platforms more rapidly than if they accessed the physical library. These mass storage systems therefore allow data consultation and updating to be managed at the request of the computer platforms from which this data originate. However, on account of the multitude and complexity of the maintenance tasks performed by these systems, when requests are transmitted by the computer platforms, the slowness and easy saturation of the processing capacities of these systems remain major drawbacks. The large-size memory means of these mass storage systems effectively have a certain bandwidth which limits the possible number of simultaneous accesses to data.
In the prior art, in particular from patent application US 2005/055512 A1, mass storage systems are known which manage the flushing of various cache volumes in relation to pre-determined priorities and in relation to periods of inactivity corresponding to a low <<demand load >> when the need to flush the cache is low (since there is large free space in the cache). This type of solution has the disadvantage of only taking into account the occupancy of the cache, and does not allow fine-tuned management of the cache in relation to demands or the management of access to the cache by the computer platforms and the system itself.
From the prior art, particularly from patent application U.S. Pat. No. 5,566,315 A, mass storage systems are known in which an allocation rate and a blocking rate are calculated to regulate flushing of the cache. This type of solution has the disadvantage of not anticipating blockage of the cache, since it consists of calculating the number of times when space allocations have failed because too much cache space is used. This type of solution thus does not allow fine-tuned management of the cache either, in relation to demand, nor does it allow management of the accesses to the cache by the computer platforms and the system itself.
Finally, from the prior art, in particular from patent application U.S. Pat. No. 5,530,850 A, storage systems are known allowing the compacting of data stored and segmented on storage devices, subsequent to changes in entered data. This type of solution also has the disadvantage of not allowing fine-tuned management of the cache in relation to demand, nor the management of access to the cache by computer platforms and the system itself. Additionally, this type of solution does not allow the triggering of compacting in relation to the activity of the storage system.