1. In a data processing system operating within a distributed storage system (DSS), a method comprising: identifying a data storage threshold value for an amount of data that can be stored within the DSS; tracking an amount of current storage usage for data stored within the DSS; determining whether the current storage usage exceeds the data storage threshold value; in response to determining that the current storage usage exceeds the data storage threshold value, calculating, based on an amount by which the current storage usage exceeds the data storage threshold value, a target number of documents that can be deleted from the DSS, wherein the current storage usage is proportional to a number of stored documents in the DSS, and 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; assigning stored documents to a plurality of groups including a set of document categories based on data characteristics of the stored documents, wherein said groups are ordered based on a relative index associated with corresponding values for data characteristics, wherein all of the stored documents assigned to at least one of the plurality of groups can be deleted in order to provide the target number of documents that can be deleted, wherein said assigning further comprises: selecting a set of document categories that are associated with the determined data characteristic parameter, wherein the selected set of document categories provide an initial set of groups to which stored documents are assigned; assigning stored documents to the selected set of document categories based on corresponding parameter values associated with the determined data characteristic parameter; determining a maximum number of document categories, from among the selected set of document categories, for which all corresponding stored documents can be removed without exceeding the target number of documents that can be deleted; in response to the maximum number being greater than zero: deleting all of the stored documents corresponding to the maximum number of document categories from among the selected set of document categories; 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 next document category of remaining, stored documents, which identified next document category is adjacent to a document category most recently identified for providing stored documents to be deleted, wherein said identified category is a target document category which comprises corresponding stored documents that can be further categorized; in response to the maximum number being equal to zero, selecting, from among the identified set of document categories, a first category as a target document category having corresponding stored documents that can be further categorized, wherein said first category holds a first position relative to other document categories based on a corresponding range of parameter values; and executing a process to further categorize stored documents from the target document category into sub-categories and delete documents from an associated one or more sub-category to arrive at the target number; and deleting all of the stored documents assigned to a selected at least one of the plurality of groups in order to remove the target number of stored documents.