Thank you for the reply. Good to learn SD2SCSI saturates bus bandwidth, though I suppose that means there could be no r/w speed gain using more than one bussed SD2SCSI in a hypothetical softRAID 0.
I am not clear on RaSCSI. I know it emulates SCSI, but I don't understand what actual the physical storage devices are with RaSCSI. Initially I thought it was a way to mount and read old SCSI drives using just the RaSCSI with no Mac, effectively a way of getting to HFS data on a naked HDD without a Mac, or even with a Mac available, still useful when one has a stack of naked SCSI drives with no idea what's on them and no motivation to open the Mac up and temporarily install HDD. I thought this improbable, but pretty neat. But I just saw a video of an SE/30 booting off a RaSCSI, and now I'm utterly confused, because RaSCSI seems now a more complicated method duplicating SD2SCSI functionality. I suppose RaSCSI slightly predates SD2SCSI.
Obviously SD2SCSI uses SD or micro SD cards. Does RaSCSI only use the Raspberry Pi's onboard micro SD storage? or is there some other configuration that includes physical HDD? afaik, there's no Pi with a SATA bus. I'd appreciate a brief explanation or a link to a complete and accurate explanation of what RaSCSI is (development thread is too looong).
Let me get my SE/30 SCSI facts straight because my investigation is old and my memory not so good.
My original understanding was that the SE/30 internal SCSI bus was fast SCSI, SCSI-2 "narrow", max bandwidth 10MB/s, but the external SCSI port bandwidth maxed at 5MB/s (SCSI-1 narrow). But now I'm not sure that is correct... no SE/30 SCSI HDD benchmark I have seen exceeds 1.5MB/s, and somewhere I read that all the SCSI bus in SE/30 was SCSI-1 narrow, 5MB/s. If the internal bus is fast SCSI 10MB/s, there may be a moderately attractive benefit to RAID 0 with 1990s HDD, but if it's all 5MB/s narrow SCSI bus speed in SE/30, there's half the room for increasing bandwidth. I guess what I need to know is if it is clear there is no old narrow or fast SCSI spinning disk that can compete with the bandwidth of SD2SCSI or RaSCSI. SD2SCSI seem to use fast SCSI, SCSI-2 "narrow," which would explain bus saturation if the SE/30 internal SCSI bus is SCSI-1.
(unrelated, recently I realized how much SATA III sucks, maxing at 600MB/s, which USB 3.0 already exceeded in 2008, while SATA III only appeared in 2009, and yet SATA III is still the ubiquitous onboard storage bus on modern logic boards 12 years later and somehow still competing against PCIe SSD, which itself appeared in 2007 and yet is still the exception rather than industry standard... but I suppose I have a long time to wait before 68kmla engineers fix SATA III, if ever, due to it having nothing to do with any 68k machine... /rant)