Detecting computer viruses includes providing a disk space having at least a portion that is partitioned into separate segments, each segment being accessed by at least one of a plurality of hosts. A first one of the segments is accessed using a different file system than a second one of the segments. An antivirus unit scans at least part of the disk space for viruses. The part of the disk space that is scanned by the antivirus unit includes at least some parts of the first and second segments. The first and second segments may correspond to different physical portions of the disk space. The first and second segments may or may not overlap. The first and second segments may correspond to logical entities. Part of the disk space that is scanned by the antivirus unit may correspond to particular types of files stored in the disk space. The disk space that is scanned by the antivirus unit may correspond to files that have been modified since a previous virus scan.