The ever-increasing demand of storage capability
leads to scaling requirement in RAID-structured storage systems.
Previous approaches to RAID scaling mainly focus on minimizing
data migration, without considering the user-level application
accesses. However, the mixed scaling I/Os and user accesses in
practical systems will interfere with each other, which results in
significant performance degradation of both the data migration
time and the user response time. In this paper, we divide
the whole storage space into multiple zones and measure the
popularity (mainly using the metric of access frequency) of
each zone. Based on the measured popularity, we propose an
online scheme, namely Popularity-based Online Scaling (POS),
to scale RAID-structured storage systems. The main idea of
POS is to scale storage areas with high popularity first so as
to better exploit workload locality. POS can efficiently alleviate
the performance degradation of user response time and data
migration time during the scaling process. It can be readily
deployed atop various conventional RAID scaling approaches to
improve their performance. To evaluate the performance of POS,
we implement FastScale and FastScale with POS (POS-FS) in
the same system. Through extensive benchmark studies on realsystem
workloads, we show that POS can efficiently reduce the
response time to user requests and scaling I/Os and improve the
sequentiality of data accesses.