In the field of mass data storage systems, there is an ongoing requirement to provide large storage capacity while at the same time improving reliability and allowing the customer to tailor such systems to his own requirements. These criteria can be satisfied with known modular system configurations wherein a number of data storage devices, e.g. magnetic disk drives, are mounted side by side in a box which also incorporates cooling fans, a power supply and some form of controller for controlling input and output of data to and from the disk files. Thus is provided a self contained unit capable of storing large amounts of data. The disk drives may be used together to provide higher reliability by, for example, allowing duplication of information or else by increasing storage capacity. If the storage devices are removable this has the added advantage of allowing the user to remove and replace defective devices or to lock away devices containing especially sensitive information.
Enclosing one or more devices and power supply within a single box imposes restrictions on the ability to maintain the devices within safe operating temperatures. Thus forced air cooling will usually be necessary, with the type of cooling system depending on the cooling requirements of the different elements within the box. One example of a modular data storage system is described in EP 320 107 wherein five 5.25 inch disk drives each mounted within a subassembly are removably inserted in the front of a drawer, the rear of which contains a power supply. Cooling of the power supply and devices is provided by two fans fixed into the rear bulkhead of the drawer which pull air past the devices and over the power supply. In such a system because the devices are of the same type, each device presumably has the same cooling requirements and therefore no provision for devices having different cooling requirements is needed.
A second example is described in EP 328 260 wherein two customer removable data storage units are mounted in canisters in the front of a drawer. A power supply and control circuitry are located at the rear of the drawer and separated from the devices by an internal bulkhead. Conventional fans provide forced air cooling of the devices and power supply. Different device types may be housed in the uniform canisters but no modification of the cooling arrangements is provided.