A Stackable Storage Array And Its Distributed Storage Management

With the proposal Internet Plus, new requirements to storage system has been proposed for the massive growth of data. Performance boost of a single storage device is limited by technological level, so the storage array has become an important device structure. There have been some solutions for capacity expansion of storage system so far, but how to increase the storage access bandwidth simultaneously with capacity expansion is still a problem.In order to design a new type of high speed and large capacity storage system to increase the speed of I/O bandwidth of storage array simultaneously with capacity expansion, the paper has put forward to a stackable storage medium scheme and designed a stackable storage array based on the scheme, which is a solution of capacity expansion simultaneous with speed increase.The stackable storage medium must be a device connected via message. For traditional parallel interface storage device, just like ATA hard disk, its controller is moved to device from host when it is updated to SATA hard disk, and it becomes the storage medium connected via message. But SATA hard disk has not been a stackable storage medium, for the storage medium address field is not contained in SATA protocol and multiple SATA hard disks are stacked together indistinguishably. Marvell Company introduced SATA port multiplier PM in 2012, which sets the port addresses to distinguish the hard disks and accomplishes SATA hard disks stacked connection. But the SATA devices work in the control of PM, they are not stackable themselves. So PM can only expand capacity without increasing I/O access bandwidth.The paper has put forward a new message protocol MES and set the port addresses in MES, including Group, Set and Channel. MES sets the array parameter by GSC and passes parameter to access the array, forming a message exchange structure supporting stackable storage medium and array. Then a stackable storage array has been designed in detail based on it. System with 10 channels(or devices) has 48 G I/O access bandwidth, and there is still much room for improvement. Now the prototype is in production.The paper has completed the following work:1. Put forward the ideas of stack for storage device and storage array. Introduce the stackable controller chip PM, analysis its operational principle and access the hard disk by PM.2. Put forward the GSC organization and establish implementation plan of Sector Pile and Super Sector.3. Define the message exchange structure MES of stackable storage array, analysis its modules and define their structure and function.4. Combine the stackable storage array with the port multiple function of PM and take advantage of FPGA parallel process to expand capacity and increase speed, which improve the system flexibility and extensibility and lay the foundation for the distributed file management.5. Build CCS2040 hardware platform by Xilinx Kintex-7 FPGA and Marvell 88SM9705, design the schematic of power, clock, reset, 88SM9705, DDR3, FLASH and JTAG, PCIe, SATA and SAS interface and accomplish the structural design of stackable storage array system.CCS2040 exchanges MES with T2080 development board via the interface of a PCIe 2.0 x4 of hard core or a PCIe 3.0 x4 of soft core, access the network via four 10 Gbit optical fiber interface on T2080 development board. It also can access the host via two 12 Gbps SAS interface to dock smoothly a high bandwidth host interface with a low rate storage device.So far, the prototype has been stereotypes and the model machine is in wiring and production process. And the FPGA program has been completed and is waiting for the model machine verification.