Improving application launch times with hybrid disks

Application launch times, which are important to users, are primarily bounded by disk seek times. A solid-state disk has a negligible seek time, but large solid-state disks are not cost-effective. A hybrid disk, consisting of a large disk drive and a flash memory of smaller capacity, can provide a reasonable compromise. However, there is no systematic approach to the allocation of portions of launch sequences to solid-state memory to achieve the shortest application launch time. We show how to reduce application launch times with a hybrid disk with pinning only a small portion of an application launch sequence into flash memory. We model the latency of a hybrid disk, analyze the behavior of application launch sequences, and formulate the choice of the optimal pinned set as an integer linear programming (ILP) problem. Experiments show that this approach reduces application launch times by 15% and 24% on average, while pinning between 5% and 10% of the application launch sequences into flash memory.