Scrubbing in Storage Virtualization Platform for Long-Term Backup Application

Scrubbing is an efficient tool to reduce latent sector errors for long-term storage. There are two established models to evaluate the effect of scrubbing. One is attributed sector errors to the contact of head and disk surface. Accordingly, sector errors are strongly related to the amount of I/O operations. The other model views the sector errors as the consequence of operating conditions. However, the sector errors in most cases are the combination of both factors. In this paper, our study analyzes, compares both methods and develops our new model basing on the average probability of both factors. Our result demonstrates that though the probability of chronic sector corruption with environmental factors is actually smaller than the probability of sector error due to I/O operations for a tagged sector, the contribution of the former to the overall sector errors is more or less equal to the latter and will ultimately exceed the latter with time increase. Furthermore, we carry out a new implementation of the deterministic scheme in our virtualization platform for long-term backup application, basing on our analysis and the locality of sector errors.