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SCSI2SD (v6) vs. RaSCSI vs. BlueSCSI
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chillin
Well-known member
There's a nice wiki here comparing the various versions of just the SCSI2SD.
So even if the SCSI2SD v6 is capable of 10MB/s, and the SCSI-2 bus in 68k Macs is also 10MB/s maximum bandwidth, it doesn't mean you'll ever see that much throughput, and apparently SCSI bandwidth in 68k Macs also depends on processor speed.
For example, the SE/30 will only see about 1.5MB/s across its internal SCSI-2 bus due to its 16MHz processor, so for SE/30, there would be little point in choosing the SCSI2SD V6 over the V5.2 hardware, which is somewhat less expensive (while supplies last).
I'm really not clear on the functionality of RaSCSI or BlueSCSI.
So even if the SCSI2SD v6 is capable of 10MB/s, and the SCSI-2 bus in 68k Macs is also 10MB/s maximum bandwidth, it doesn't mean you'll ever see that much throughput, and apparently SCSI bandwidth in 68k Macs also depends on processor speed.
For example, the SE/30 will only see about 1.5MB/s across its internal SCSI-2 bus due to its 16MHz processor, so for SE/30, there would be little point in choosing the SCSI2SD V6 over the V5.2 hardware, which is somewhat less expensive (while supplies last).
I'm really not clear on the functionality of RaSCSI or BlueSCSI.
cheesestraws
Well-known member
Yes. To get a sensible answer you will need to specify what machine you're expecting to see the transfer speeds on.
Tom2112
Well-known member
Joe from Joe's Computer Museum has a benchmark video about this. (Sorry, it doesn't include the RaSCSI) but did include an IBM HDD for comparison.
The results were mixed. The BlueSCSI was slowest, but not by a huge margin, and it had faster seek times than the SCSI2SD models.
The benchmarks on the RaSCSI site are a little disappointing, not in speed, but in that they included a Pi 4, Pi 2, and Pi Zero but not a Pi3B+? I would think the 3B+ would be the sweet spot. It doesn't get hot, unlike the Pi 4 (could be used in a mini-bake oven), and is more powerful than the Pi 2.
I was working with my RaSCSI on a Pi 3B+ over the weekend, and it was slow going - but that was likely more due to the Mac Classic's 8Mhz 68000 rather than the RaSCSI. Crikey that machine is slow.
The benchmarks on the RaSCSI site are a little disappointing, not in speed, but in that they included a Pi 4, Pi 2, and Pi Zero but not a Pi3B+? I would think the 3B+ would be the sweet spot. It doesn't get hot, unlike the Pi 4 (could be used in a mini-bake oven), and is more powerful than the Pi 2.
I was working with my RaSCSI on a Pi 3B+ over the weekend, and it was slow going - but that was likely more due to the Mac Classic's 8Mhz 68000 rather than the RaSCSI. Crikey that machine is slow.
The fastest of this group, out and out, is hands down the SCSI2SD v6. If this is for the IIfx you've mentioned in some other threads, and you have a SCSI card in it, the v6 is probably what you want.
I have one in an 8600/300 and can get 7.5 megabytes/second out of it. Joethezombie put one in a IIfx and was able to get an entire 10 megabytes/second out of it. The notes on that are here: https://68kmla.org/bb/index.php?threads/cheap-ide-on-scsi-bus-solution.32521/post-348293 - the original context of that thread was a PowerMac 8100 but a few different types of machines came up.
None of the other devices come close to that fast in out-and-out drag races.
Random r/w speed and total IOPS on any of the disk replacers is going to be worlds better than an original disk so I don't know if the differences in that metric matter a whole lot, but, again, it depends on what you need to do.
However, most Macs have terrible SCSI buses and Classic Mac OS itself isn't really very sensitive to disk performance, so on most Macs with SCSI, a bluescsi or a scsi2sd v5 variant will be perfectly cromulent.
If this is a PCI powermac and you need performance: an IDE card and an SD <> IDE adapter or a SATA card is a better bet.
If you have some super high end use cases like "compiling software 24/7 for years on end" (similar to, say, johnklos) then your money is better spent on something like an Acard SCSI <> SATA adapters.
I have one in an 8600/300 and can get 7.5 megabytes/second out of it. Joethezombie put one in a IIfx and was able to get an entire 10 megabytes/second out of it. The notes on that are here: https://68kmla.org/bb/index.php?threads/cheap-ide-on-scsi-bus-solution.32521/post-348293 - the original context of that thread was a PowerMac 8100 but a few different types of machines came up.
None of the other devices come close to that fast in out-and-out drag races.
Random r/w speed and total IOPS on any of the disk replacers is going to be worlds better than an original disk so I don't know if the differences in that metric matter a whole lot, but, again, it depends on what you need to do.
However, most Macs have terrible SCSI buses and Classic Mac OS itself isn't really very sensitive to disk performance, so on most Macs with SCSI, a bluescsi or a scsi2sd v5 variant will be perfectly cromulent.
If this is a PCI powermac and you need performance: an IDE card and an SD <> IDE adapter or a SATA card is a better bet.
If you have some super high end use cases like "compiling software 24/7 for years on end" (similar to, say, johnklos) then your money is better spent on something like an Acard SCSI <> SATA adapters.
