Technologies are described for implementing container space management (CSM) in a data storage system. Performance may be improved by ensuring that the maximum number of drive spindles is made available to I/O loads. This may be accomplished by distributing data equally amongst all drive spindles, even if the drive spindles are in different logical drives. A workflow analysis may be performed to determine when the I/O load on the storage system is low and thus identify preferred times for background data re-striping. Data may be re-striped in a minimum number of movements using a data placement algorithm and data placement maps to select data to be re-striped. The data may be re-striped such that the most frequently accessed data within a tier is moved first. Such re-striping can be performed in a manner which optimizes the performance of the storage system both during, and after, the re-striping process.