In recent years, the need to build solid state drive (SSD)-based cloud storage systems has been increasing in order to process the big data generated by lots of Internet of Things devices and Internet users. Because these kinds of cloud systems require high performance and reliable storage, the use of flash-based Redundant Array of Independent Disks (RAID) will increase. But in flash-based RAID storage, parity data must be updated with every data write operation, which can more quickly overwhelm SSD's lifespan. To solve this problem, this letter proposes parity data deduplication for OpenStack cloud storage systems using an all flash array. Unlike the traditional data deduplication method, it only removes parity data, which will be stored in the parity disks of the all flash array. Experiments show that the proposed parity data deduplication method can efficiently reduce the number of parity data write operations, compared to the traditional data deduplication method.

We evaluated software maintenance of an open source cloud platform system we developed using an agile software development method. We previously reported on a rapid service launch using the agile software development method in spite of large-scale development. For this study, we analyzed inquiries and the defect removal efficiency of our recently developed software throughout one-year operation. We found that the defect removal efficiency of our recently developed software was 98%. This indicates that we could achieve sufficient quality in spite of large-scale agile development. In term of maintenance process, we could answer all enquiries within three business days and could conduct version-upgrade fast. Thus, we conclude that software maintenance of agile software development is not ineffective.

In this paper, we evaluate a method of agile software development for carrier Cloud service platform development. It is generally said that agile software development is suitable for small-scale development, but we adopt it for the development which has more than 30 members. We attempted to enable automatic regression tests for each iteration when we adopted agile software development, so that we could start our Cloud service sufficiently fast. We compared and evaluated software reliability growth curves, regression test efforts and bug causes with waterfall development.