BB wrote:
Serial ATA Interface (Rev 2.6); Data transfer rate: 1.5Gb/sec |
That is not the read speed of the drive, that is only the interface speed. In the case of CD/DVD/Blu-ray the interface speed is several times faster than the drive actually is. The physical transfer of the bits off of the spinning disk is the limiting factor.
The speed difference between USB 2.0 and FW400 isn't all that much but FW400 uses far less cpu cycles for the data transfer.
According to several sites the maximum read speed of BD on that drive is 10X (just under 45 Mbytes/sec) which is pushing the limits of USB 2.0 and FW400 but the 3X you report means something is definitely amiss somewhere in the system. It could be a drive problem, a disk problem, or something else.
With my Thunderbolt to FW800 adapter I'm getting about 170 Mbytes/sec transfer from my drives that use RAID 0 mirroring and the limiting factor is definitely the data transfer between the spinning platter(s) and the drive electronic buffer.