15. The computer program product of claim 11 , wherein the program code further comprises program code for: determining whether a count of all the removed stored documents is less than the target number of documents that can be deleted; and in response to the count being less than the target number of stored documents that can be deleted, identifying a document category of remaining, stored documents, which identified document category is adj acent to a document category most recently identified for providing stored documents to be deleted, wherein the identified category is a target document category which comprises corresponding stored documents that can be further categorized.
11. A computer program product comprising: a non-transitory computer readable medium; and program code on the non-transitory computer readable medium that when executed within a data processing device within a distributed storage system (DSS), the program code provides the functionality of; identifying a pre-established data storage threshold value for an amount of data that can be stored within the DSS; tracking a current storage usage for an amount of data stored within the DSS; determining whether the current storage usage exceeds the pre-established data storage threshold value; in response to determining that the current storage usage exceeds the pre-established data storage threshold value, calculating a target number of documents that can be deleted from the DSS based on an amount by which the current storage usage exceeds the pre-established data storage threshold value, wherein the current storage usage is proportional to a number of stored documents in the DSS, wherein the stored documents have a same document type; determining a data characteristic parameter that can be used to identify parameter values of the stored documents, which parameter values enable the stored documents to be assigned into a plurality of groups which include a set of document categories, wherein the groups are ordered based on a relative index associated with corresponding parameter values, wherein all of the stored documents assigned to at least one of the plurality of groups can be deleted, based on an order associated with the relative index of the document categories, in order to provide the target number of documents that can be deleted; assigning stored documents to the plurality of groups using corresponding parameter values; and deleting all of the stored documents assigned to at least one of the plurality of groups in order to remove the target number of stored documents.