Building Large Storage Based On Flash Disks

Flash SSDs are a technology that has the potential of drastically changing the architecture of a DBMS. In this paper, the authors examine the properties of a storage space built on SSDs with RAID and how these affect data intensive systems. While they observed the expected performance improvements of one to two orders of magnitude of SSD-only storage over HDD storage, RAID-SSD systems showed interesting effects and large performance degradation: the SSD read-write asymmetry and the write behavior are amplified due to RAID; scalability issues in a RAID-based storage system appear because of inadequate controllers; fragmentation and distribution issues affect performance much more than expected.