原文討論在這
http://www.hardforum.com/showthread.php?t=1484614

OK.　看來官方文件 那說法不對.確實沒有分in 跟out .就像hub


NOTE: Even though the printed circuit board says "to controller" on Ports #8 and #9, this is trivial. The SAS expander acts much like an ethernet switch- you can use any port for input or output, it makes no difference, there's nothing unique about any one port from the others. HP suggests using the last two ports only because its the end of the range

那這樣的話 36 port SAS expander .爽的話.
用掉一個 sas 4x 接控制卡.　可接上 32 pcs HDD