| Storage technology has revolutionary changes these days. These changes happen in three areas. The first one is the rapid growth of storage capacity. The next one is the response time of data ready. The last one is the changing structure of data storage. So data storage devices should have high quality. As RAID enclosure system is the key storage device, its reliability and manageability has great impact to the performance and stability of whole storage system.This paper describes a method of design and implementation of SCSI enclosure service software for new generation high-end and midrange RAID based storage system. Author found several defects that were needed to be improved during the study of old enclosure in IBM. For example, hardware cost is high, pair controller communication is inefficient, supported SES pages is less, etc. This paper improves it a lot based on the following key points:1. Old enclosure was using Fiber Channel, including front end, back end, and hard drive interface. Hardware cost is really high. In this project, front end interface is still Fiber Channel, but back end and hard drive interface is using SAS[1][2] technology. Hardware cost is reduced without sacrifice to product performance. Performance price ratio is also greatly improved.2. UART channels are used for pair SAS expander communication. Communication protocol model is re-designed to support full duplex and to improve the stability and efficiency of pair communication. Old enclosure was using I2C bus[3], collision and deadlock happened sometimes. It has high possibility of collision especially during system boots up, as I2C bus is quite busy with read/write operations.3. Support more SES[4] pages. Not only support mandatory SES pages, but also support optional SES pages of the specification. Host machine could have more information of enclosure and have more ways to control enclosure via SES pages.4. Re-design fan control algorithm. Compared to old product, it’s quite stable. The rotation of fan will not sharply change in normal situation. In the test environment, it has quick response to the change of temperature.5. Support more enclosure events and SES element indicators (LED). Design and implement a new control model of indicators. In theory, it can support infinite software indicators with the limited hardware indicators.The research and implementation of the above key points ensure the stability and mature of the product. Based on author’s theoretical analysis in early stage, huge programming practices and device debugging on site for a long time, he has made advanced and practical research of defects improvement for the family of this product. |
