1. A method, comprising determining, via a processor, a user catalog that has a greater amount of available space in comparison to other user catalogs of a plurality of user catalogs, wherein there is a lesser amount of contention among a plurality of threads or processes to access the determined user catalog in comparison to the other user catalogs, and wherein the user catalog is used to store a new data set; subsequent to determining the user catalog, inserting in a group table, an entry that indicates a data set name corresponding to the new data set and an index to the determined user catalog; directing requests for any data sets to the group table; determining that an error occurs while performing at least one of an update to a data set and a read access on the data set; determining which user catalog causes the error and invoking a sequential read on the user catalog that causes the error; for each entry of the user catalog that causes the error, determining a suitable user catalog to which the data set should be moved; and updating one or more entries of the group table, in response to moving the data set to the determined suitable user catalog.