一直看到有些服务器同为使用的LSI的3008芯片，有些支持把磁盘做成RAID(如Dell的H330等),有些却只有直连的功能。咨询公司的老司机告知是LSI SAS3008提供多种类型的控制器，搜索了一些IT与IR的区别，网上的信息也比较少，可以借用超微官网上的一个问答，如下：
Question：
For LSI Host Bus Adapter (HBA) firmware, what is the difference between IT mode and IR mode?
Answer：
The two firmware types are Initiator Target (IT) and Integrated RAID (IR).
IR is the typical hardware RAID firmware that the internal cards or boards
ship with.
The IT firmware, on the other hand, is the Initiator Target
firmware which is designed to allow a SAS HBA to connect to up to 256
devices using SAS Expanders. The IT firmware is typically shipped on
external cards. The IT firmware does not have any RAID capabilities and
simply acts as an HBA.
写出来，让更多有同类疑惑的同学更加容易搜索到。
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