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BlueScsi, SCSI Sd or Ra SCSI device for a Mac 950?
- Thread starter Jorge E
- Start date
Hey, welcome in!
Any of these should be fine for general use. I have a 32-gig card configured for around 32 gigs in a SCSI2SD v5 in my Quadra 840av and it works well. It's my understanding that MacSD, BlueSCSI, and RaSCSI all perform similar.
if you've got some use case where you are sensitive to disk performance (like if you have the Apple Workgroup Server 950 PDS card) then the best option is the SCSI2SD v6. It's ~3-6x faster than all the other options. I have a SCSI2SD v6 in my 8600/300 and it works great.
EDIT/Add: One more note: in my experience disk performance doesn't really magger in Classic Mac OS and Classic Mac OS is poorly architected enough that you mostly don't notice the difference. SCSI2SD v6 is at the extreme upper end of what's reasonable or necessary for any 68k Mac but it's at the low end of what's reasoanble for a PCI PowerMac. I'm sure my 8600 would run fine with a slower adapter, but I rarely have to wait on it for disk related reasons. The V6 with the card I'm using does a little bit better than stock disks, on top of the benefit of using solid state media where seeks are near instant compared to old conventional hard disks.
That said, a SCSI2SD v6 costs about 2x what a v5 does, so my personal recommendation is to consider starting with one of the slower options.
Any of these should be fine for general use. I have a 32-gig card configured for around 32 gigs in a SCSI2SD v5 in my Quadra 840av and it works well. It's my understanding that MacSD, BlueSCSI, and RaSCSI all perform similar.
if you've got some use case where you are sensitive to disk performance (like if you have the Apple Workgroup Server 950 PDS card) then the best option is the SCSI2SD v6. It's ~3-6x faster than all the other options. I have a SCSI2SD v6 in my 8600/300 and it works great.
EDIT/Add: One more note: in my experience disk performance doesn't really magger in Classic Mac OS and Classic Mac OS is poorly architected enough that you mostly don't notice the difference. SCSI2SD v6 is at the extreme upper end of what's reasonable or necessary for any 68k Mac but it's at the low end of what's reasoanble for a PCI PowerMac. I'm sure my 8600 would run fine with a slower adapter, but I rarely have to wait on it for disk related reasons. The V6 with the card I'm using does a little bit better than stock disks, on top of the benefit of using solid state media where seeks are near instant compared to old conventional hard disks.
That said, a SCSI2SD v6 costs about 2x what a v5 does, so my personal recommendation is to consider starting with one of the slower options.
cheesestraws
Well-known member
Welcome to the forums!
"It depends" isn't a helpful answer, but it's the only honest one. Notes on each of the options I know of:
It's very difficult to recommend BlueSCSI these days unless you build your own. The project started off well but has spiralled into extremely unprofessional behaviour and hardware that is at best adequate value for money if you get a prebuilt one. However, if you don't actually intend to interact with them, it's adequate for purpose so long as you're happy with the fact that it's driving its microcontroller out of spec. How much does that matter? Hard to tell.
scsi2sd has its own issues especially around the usability of its setup tools, but is fundamentally competent: the hardware is considerably better than BlueSCSI, but it is also more expensive.
RaSCSI is more a 'construction kit' than a finished product in my mind, though it's made significant strides towards end-user friendliness lately. It's a bit of a swiss-army chainsaw: it's very, very powerful, but that power makes the whole thing more complex to use, as it usually does with systems.
Another option is MacSD. MacSD has really nice features and usability, IME, especially if you want to use CD-ROM images/emulation. However, it comes at a higher cost:raw performance ratio than the others.
"It depends" isn't a helpful answer, but it's the only honest one. Notes on each of the options I know of:
It's very difficult to recommend BlueSCSI these days unless you build your own. The project started off well but has spiralled into extremely unprofessional behaviour and hardware that is at best adequate value for money if you get a prebuilt one. However, if you don't actually intend to interact with them, it's adequate for purpose so long as you're happy with the fact that it's driving its microcontroller out of spec. How much does that matter? Hard to tell.
scsi2sd has its own issues especially around the usability of its setup tools, but is fundamentally competent: the hardware is considerably better than BlueSCSI, but it is also more expensive.
RaSCSI is more a 'construction kit' than a finished product in my mind, though it's made significant strides towards end-user friendliness lately. It's a bit of a swiss-army chainsaw: it's very, very powerful, but that power makes the whole thing more complex to use, as it usually does with systems.
Another option is MacSD. MacSD has really nice features and usability, IME, especially if you want to use CD-ROM images/emulation. However, it comes at a higher cost:raw performance ratio than the others.
cheesestraws
Well-known member
Absolutely. The device you can get hold of is the best device
.I'm very curious about what you do with architectural drawings on your 950, if it's not rude to ask about it. That sounds very interesting.
cheesestraws
Well-known member
That's really interesting. I love the old Claris applications. Thankyou for telling me about your usage
mdeverhart
Well-known member
Do you have a reference for that? I feel like I may have seen something about that in passing, but I’d forgotten about it. Now I’m wondering if I should be worrying about the ones I have in my SE and Duo…
cheesestraws
Well-known member
SCSI-1 drivers are meant to be able to sink 48mA per line. Here's an old IBM document that states that explicitly: http://ps-2.kev009.com/eprmhtml/eprmb/h1293.htm, RaSCSI folks have this to say: https://github.com/akuker/RASCSI/wiki/Transceiver-Comparison, and pulling the datasheet for a totally random SCSI controller out of my downloads folder, here's what it has to say:
The STM32's GPIO lines, per the datasheet, have an absolute maximum rating of 25 mA (this is from the STM32F103C8 datasheet which is I believe what my bluepill boards have on them:
While this datasheet doesn't give an absolute maximum rating for the sum of all GPIOs, the maximum total current that's allowed to flow through the ground pin is 150mA:
And this would be easily overloaded by even only 3 of the lines sinking the maximum 48 mA.
Even if we look at a SCSI bus which only contains the BlueSCSI and some termination, SCSI terminators are supposed to aim to supply 24 mA ish per pin of source current when necessary (see "Understanding the single-ended SCSI Bus", chapter 4). So even just with a normal standard-compliant terminator, you're potentially overloading the power handling capabilities of the MCU if six lines are sinking at once.
So, it's out of spec, the question is how much does this matter in practice? And that's a more complicated question I think, because it's really a question about risk. This will shorten the life of the microcontroller, and eventually the thing will die. But how long "eventually" is hasn't really been quantified yet, nor is what the upshot of it dying is. I think it's reasonably unlikely it would take the SD card out with it, so if you're in a position to consider bluepill boards as basically consumable (although with a long replacement window), the risk might be OK. (Though it feels rather wasteful)
For hobby use—it's probably OKish. I've got bluescsis of a slightly modified design in some of my compacts that I don't use very often, and I'm OK with the above for that. If it was something I used daily I would probably reconsider; and if, like the OP, I was doing actual work on the things, I wouldn't even consider BlueSCSI.
The real problem is that as far as I know the BlueSCSI folks get weirdly defensive when you point out, however politely, that their hardware is running outside of spec (or say anything even remotely critical about their hardware), and so this seems unlikely to get fixed unless they can pretend it was their own idea somehow. Big sigh.
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Oh Thank you very much. I appreciate your kindness. I send you PM
mdeverhart
Well-known member
@cheesestraws Thanks for the detailed response!
Skate323k137
Well-known member
I concur, the v5 is fine for 68k macs, PPC does benefit from the v6.
I did some benchmarking on this a while ago https://68kmla.org/bb/index.php?threads/benchmarking-scsi2sd-devices-in-a-pci-powermac.31139/
In that thread, here's what I came up with eventually for my 7500 anyway. I hope this info is helpful.
First of all, welcome to the forum.
It's great you are using a 950 for real work still, most of us don't seem to know what to do with our old Macs but we collect them anyway.
As per the advice above, if you're relying on this for real work and want lonevity/reliaiblity, I'd say the SCSI2SD or MacSD are your best options. The RaSCSI is good but it's more of a hobby/tinker thing (not saying it can't be reliable, but it's certainly less 'ready to go' than other options). BlueSCSI is fine and I have used them in a lot of Macs, but as mentioned above there are some things to bear in mind with that option.
