To free up storage space on a SAN with minimal effort and no additional cost, the following methods can be used: * Configuring compression (Answer A):Compression reduces the size of files stored on the SAN, allowing more data to be stored in the same space. * Enabling deduplication (Answer E):Deduplication identifies and removes duplicate copies of data, reducing the amount of space required for storage. * Deleting old and unused files (Option B):While effective, this requires manual effort and may not be the best long-term solution. * Increasing the number of IOPS (Option C):This relates to improving performance, not reducing storage space. * Decreasing the RAID level (Option D):Lowering the RAID level could reduce redundancy, which may free up space but also decreases fault tolerance. * Upgrading the filesystem type (Option F):This is a complex process that doesn't directly reduce storage usage. CompTIA Server+ Reference:This topic is covered underSK0-005 Objective 3.2: Summarize storage technologies and solutions.