The Design, Implementation, and Framework for a Linux-Based Temperature-Sensitive Storage System

Temperature Sensitive Storage (TSS) is a data stor age architecture that keeps track ofthe access fre quencies of data and uses this information to man age storage e®ciently and eectively. The term tem perature refers to the access frequency of the data. TSS is a hierarchical storage architecture with fre quently accessed data residing in a storage device with faster access time, while less frequently ac cessed data placed in a device which is more storage e®cient. The hierarchy iscurrently a 3-tier archi tecture consisting of declustered RAID 1 (RAID1), RAID 5 (RAID5) and compressed RAID 5 (cRAID5) storage devices. The data is dynamically moved be tween these tiers, depending on their access frequen cies. TSS, along with fast access and e®ciency of storage, also provides reliability of data by incorporating re dundancy in the system through the use of RAID architecture. Simple policies for dynamically managing the data have been implemented as user level daemon pro cesses. They are independent of the low level im plementation of the TSS driver. They make useof certain ioctl() calls provided by the TSS device driver. In this paper we discuss the design, implementa tion and policy framework of a Linux based TSS, and compare its performance with static RAID sys tems.