Minimizing Hard Disk Drive Failure and Data Loss/Data Reduction
Reducing the amount of data one has can reduce the number of hard disk drives needed to store that data and its backups. This consequently decreases the probability of failure of any one drive in a given period of time. Having a lesser amount of data also makes it easier to safeguard it using redundancy methods.
Routine cleanup edit
Routinely going through one's files and deleting those which are no longer useful is a basic way of reducing one's data. Having a reduced number of files can also make it easier to find those for which there may be a need. The same applies to uninstalling applications which are no longer required. This can perhaps be done once every three months.
Data compression edit
Data compression software can be used to compress files or sets of files so they occupy less space. One such utility is 7-Zip. This applies particularly to files that do not get modified and are likely to benefit from compression, e.g. archived sets of documents and spreadsheets. In contrast, depending upon the specific format, digital media files are often highly compressed as it is, and are not likely to be compressed much further.
Besides the space savings, an additional benefit of keeping files compressed is that they will back up faster than if they were uncompressed. This does not apply to NTFS compression, which actually slows backups.