WARP:Warp Around Data Placement Technique for Serpentine Tapes

Due to the information explosion we are witnessing, a growing number of applications store, maintain, and retrieve large volumes of data, where the data is required to be available online or near-online [10, 3, 8]. These data repositories are implemented using hierarchical storage structures (HSS). One of the components of HSS is tertiary storage, which provides a cost-effective storage for the vast amount of data manipulated by these applications. To bridge the access-gap between the tertiary storage and the secondary storage, we propose a data placement technique, namely WARP: Wrap ARound data Placement. WARP may reduce the access time by 1 order of magnitude, depending on the tape device specifications and object sizes. An important feature of WARP is that it optimizes access-time independently of the retrieval order. We have implemented this technique on an IBM 3590 tape drive and have observed up to 5 times improvement in access-time as compared to other data placement techniques. Moreover, we report on the use of WARP with multiple load/unload position tapes (of the future).