An apparatus in one embodiment comprises a multi-tier storage system having at least a front-end storage tier, a back-end storage tier and a data mover module configured to control movement of data between the storage tiers. The multi-tier storage system is configured to receive a plurality of files, such as relatively small size files containing data from respective Internet of Things (IoT) devices. The front-end storage tier comprises a file system and at least one key-value store. The multi-tier storage system is configured to combine multiple ones of the received files written to at least one specified directory of the file system into an object for storage in association with a key in the key-value store. The object comprises multiple sub-keys identifying respective ones of the multiple files within the object. The data mover module may be configured to copy the object from the key-value store to the directory.