the performance of SAS is not better than SCSI in FreeBSD, WHY?

[Tzu-Hua Wang]

Dear All:
I have bought the HP ProLiant DL380 G5 (SAS HD and RAID Controller)

By using "diskinfo -t", the information of HD performace is:
=========================================================
/dev/da1
        512             # sectorsize
        146778685440    # mediasize in bytes (137G)
        286677120       # mediasize in sectors
        35132           # Cylinders according to firmware.
        255             # Heads according to firmware.
        32              # Sectors according to firmware.

Seek times:
        Full stroke:      250 iter in   2.578974 sec =   10.316 msec
        Half stroke:      250 iter in   2.099233 sec =    8.397 msec
        Quarter stroke:   500 iter in   2.277551 sec =    4.555 msec
        Short forward:    400 iter in   2.018527 sec =    5.046 msec
        Short backward:   400 iter in   2.636941 sec =    6.592 msec
        Seq outer:       2048 iter in   2.052169 sec =    1.002 msec
        Seq inner:       2048 iter in   2.052077 sec =    1.002 msec
Transfer rates:
        outside:       102400 kbytes in   2.547162 sec =    40202 kbytes/sec
        middle:        102400 kbytes in   3.151423 sec =    32493 kbytes/sec
        inside:        102400 kbytes in   3.342559 sec =    30635 kbytes/sec

=========================================================


I have an old server, only SCSI HD and RAID Controller.
By using "diskinfo -t", the information of HD performace is:
=========================================================
/dev/da0
        512             # sectorsize
        73543163904     # mediasize in bytes (68G)
        143638992       # mediasize in sectors
        8941            # Cylinders according to firmware.
        255             # Heads according to firmware.
        63              # Sectors according to firmware.

Seek times:
        Full stroke:      250 iter in   2.968575 sec =   11.874 msec
        Half stroke:      250 iter in   2.218879 sec =    8.876 msec
        Quarter stroke:   500 iter in   3.569766 sec =    7.140 msec
        Short forward:    400 iter in   1.798317 sec =    4.496 msec
        Short backward:   400 iter in   1.872876 sec =    4.682 msec
        Seq outer:       2048 iter in   0.258105 sec =    0.126 msec
        Seq inner:       2048 iter in   0.458751 sec =    0.224 msec
Transfer rates:
        outside:       102400 kbytes in   1.181019 sec =    86705 kbytes/sec
        middle:        102400 kbytes in   1.405735 sec =    72844 kbytes/sec
        inside:        102400 kbytes in   2.100786 sec =    48744 kbytes/sec
==========================================================

Generally, the performace of SAS in FreeBSD is far worse than SCSI in FreeBSD.
Is it normal? How can I do to improve the performance of SAS HD in FreeBSD?

Thank you