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What's the fastest drive option for a SCSI Mac?

greystash

Well-known member
From what I have found it seems that SCSI2SD and BlueSCSI have ~2MB/s read and write vs ~5MB/s (correct me if I am wrong) on an old SCSI HD.
What would be the fastest performing drive type on a SCSI Power Mac, is there anything I am missing?
 

max1zzz

Well-known member
I have heard good things about the new RP2040 based ZuluSCSI, haven't personally tested one though

Another option is modern SCSI drives, A fast 80 or 68pin scsi drive with the appropriate adapter will still outperform most of the emulation devices on the market
 

lobust

Well-known member
Those benchmarks posted by @Paulie have got me wondering...

No experience with the ZuluSCSI here, but using the same benchmark, my SCSI2SD v6 benched somewhat faster on the internal bus (Also a Quadra 650/800, but stock clocks) compared to his, reaching 2.8something MB/S. I'm curious to know why that is... Pretty sure I am also using a Sandisk 16GB card, but I will check specifics when I am home later. Obviously still not as fast as the ZS.

However;

I have gotten over 8MB/s out of the SCSI2SD V6 when attached to a SEIV, but annoyingly I did not document those results. I did document the difference between Q800 onboard and an SEII however, which proves that the SCSI2SD v6 is being bottlenecked by the internal bus: https://tinkerdifferent.com/threads/atto-silicon-express-ii-nubus.1153/

And yet, the ZS seems to be able to get much closer to the theoretical maximum throughput of the internal bus?

Is @Paulie's overclock raising the bandwidth ceiling of the internal bus allowing the ZS to get closer to the 5MB/s theoretical maximum? If so, why does his SCSI2SD v6 then bench slower than mine running at stock clocks?

I think we need some larger sample sizes to draw definitive conclusions...

I recently acquired a Jackhammer for testing, and I think now need to get my hands on a ZS for comparison!

And next time I will document my results properly!

BTW, I am pretty sure the butterfly test in that benchmark killed one of my few remaining mechanical hard drives (it sounded horrible, and the drive failed to format afterwards), so I don't use it anymore for those.
 

Phipli

Well-known member
Fast SCSI spinning drives are faster than any of the SD card offerings arent they? @greystash - did you specifically mean excluding spinning drives?

I have a ST318418N thats very quick in old macs. Similar early 2000s SCSI drives tend to be faster than my SCSI2SD except for random r/w.

I don't have a SCSI2SD v6 to compare.

This is in an overclocked (33mhz) LC 475 :

IMG_20220820_004259_003.jpg
 
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Skate323k137

Well-known member
I believe @rabbitholecomputing has talked to the speed of the ZuluSCSI, it's very nice, but slightly slower than the V6 scsi2sd. I used a V6 in my 7500 until I switched to a PCI RAID card which is absurdly fast.
 

MrFahrenheit

Well-known member
I have large u320 SCSI SCA80 drives in my Mac’s which are incredibly fast. Using the SCA80 to 50 adapter made by a forum member here (apologize but I can’t remember who). They saturate the bus in read and write operations.

However: the biggest convenience with SD card solutions is reliability, cost for additional SD cards being reasonable, and file transfer from even a Windows machine being convenient. All of these probably outweigh the lightning speed I’ve seen on the u320 drives.

I would love to see benchmarks comparing a variety of the SD card solutions using a standardized app, which we could all compare with other solutions (Zip, Jaz, Syquest, old spinning Quantum’s, u320 SCSI, and even magneto optical).
 

Phipli

Well-known member
I have large u320 SCSI SCA80 drives in my Mac’s which are incredibly fast. Using the SCA80 to 50 adapter made by a forum member here (apologize but I can’t remember who). They saturate the bus in read and write operations.

However: the biggest convenience with SD card solutions is reliability, cost for additional SD cards being reasonable, and file transfer from even a Windows machine being convenient. All of these probably outweigh the lightning speed I’ve seen on the u320 drives.

I would love to see benchmarks comparing a variety of the SD card solutions using a standardized app, which we could all compare with other solutions (Zip, Jaz, Syquest, old spinning Quantum’s, u320 SCSI, and even magneto optical).
Also with different system software versions, as I often see that forgotten, and in video it certainly makes a difference, and I believe I've seen differences in disk speed by OS version? Perhaps it was PPC and depended on how much driver code was emulated? Not certain.

Perhaps I can run a test in a couple of OS versions this evening in the 475 with a fast spinning disk.
 

Cory5412

Daring Pioneer of the Future
Staff member
This is a little bit disorganized because it's early, but:

As far as I know, the SCSI2SD v6 is still the drag race champion among the modern solutions. Mine gets ~7MB/sec read and ~4MB/sec write in my 8600/300. My benches are over at https://68kmla.org/bb/index.php?threads/cheap-ide-on-scsi-bus-solution.32521/ - in that thread we found that using a high grade SD card does matter.

The numbers Paulie posted for the ZuluSCSI look great and I'm looking forward to getting one or two for some of my machines that need modern storage. I have a SCSI2SD v5 in my 840av and likely don' want to pull that machine apart again, but my personal theory is that ZuluSCSI is gonna be Good Enough for basically all my other SCSI-havin' macs. Realistically, even my beige G3, unless I wanted to get serious about video capture with that machine, for some reason.

I know this isn't what was asked but I think what's "important to get" really depends on the type of build you're looking to do, what you want to do with it, what you want to get out of it, etc etc.

Classic Mac OS is terrible at all i/o, networking and disk especially. It makes up for that by being very lightweight, even for its time. You simply don't really need good disk performance unless you want to do video editing or similar multimedia authoring or win at benchmarks. To add to cheesestraw's point -- seeks are more important to how fast a computer feels -- even on Classic Mac OS, which, again, mostly doesn't do a good job taking advantage of more throughput.

(Basically -- I'm perhaps not really getting much out of my SCSI2SDv6 winning drag races in my 8600, especially what with the way people talked about getting like 2MB/sec on a 9500 being impressive -- it's not impressive but it's probably perfectly fine for most things.)

With that in mind, another option to win benchmarks (and capacity and reliability) as you get to the PCI era is to drop in a SATA card. Should outdo basically everything else in practical terms, because you'll get the high speed of SATA itself as well as the low seeks of SSDs. The only real bummer is Classic Mac OS has a 2TB volume limit.
 

Phipli

Well-known member
The only real bummer is Classic Mac OS has a 2TB volume limit.
Further to this, Drive Setup has a bug in the partitioning part - it looks like it holds the disk size in too smaller variable for TB magnitude drives. I had to format my 1.5TB SATA drive in my 9600 using third party tools to be able to create a number of small partitions. I think I used FWB HDT. Its a couple of years back now though. I believe Disk Utility would be fine too.

This is obviously a daft problem to have, but it was the first spare disk that came to hand that wasn't failing.
 
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Coloruser

Well-known member
I guess it´s no problem to saturate the bus on older 68k macs, even the faster and more sophisticated SCSI bus on later Quadras. But the fast SCSI bus on Tsunami/TNT style PowerMacs is a different kind of animal. The beige G3 was a step back as his SCSI imterface was back to the 5mb style - of course the IDE interface was faster. I am using an old Umax Stormsurge with SCA drive and adapter on its fast-SCSI bus and non of the SCi-SD interfaces can live up to the read/write speed (i have SCSI2SD vs 5 and 6). Seek time is a different story though.
 

greystash

Well-known member
Per @Paulie 's recent benchmarks, the ZuluSCSI seems to be the current winner:


That said, bear in mind whether raw throughput is actually what you want: latency/seek speed is often more relevant to interactive use, and a lot of the benchmarks out there don't talk about that, so I don't know which device has the best seek speed.
Thanks @cheesestraws I'll look into getting one of these!

And thank you @max1zzz @Phipli @MrFahrenheit I think I'll try a newer SCSI disk first.

I'm upgrading my PM 6100 and would happily consider a better/newer SCSI HDD if they are faster. I'm mostly wanting to use it for casual gaming, I know old Mac games aren't very HD intensive but a general system speed boost would be nice. I'm not worried about convenience since I do all my transfers/syncing/backups with a NAS over ethernet between machines. I think I'll try getting a ZuluSCSI (when I've got the extra cash!) and a better SCSI drive and then compare results.

Thank you everyone for the advice it's greatly appreciated!
 

max1zzz

Well-known member
And thank you @max1zzz @Phipli @MrFahrenheit I think I'll try a newer SCSI disk first.
Well if you need a SCA80 to 50pin adapter let me know - I happen to make ones with full termination :) (which the cheap ebay adapters usually lack)
 

Skate323k137

Well-known member
Thanks @cheesestraws I'll look into getting one of these!

And thank you @max1zzz @Phipli @MrFahrenheit I think I'll try a newer SCSI disk first.

I'm upgrading my PM 6100 and would happily consider a better/newer SCSI HDD if they are faster. I'm mostly wanting to use it for casual gaming, I know old Mac games aren't very HD intensive but a general system speed boost would be nice. I'm not worried about convenience since I do all my transfers/syncing/backups with a NAS over ethernet between machines. I think I'll try getting a ZuluSCSI (when I've got the extra cash!) and a better SCSI drive and then compare results.

Thank you everyone for the advice it's greatly appreciated!
Presuming the Zulu is close to the V6, which I have no reason to doubt at all, you may find useful my numbers from benchmarking a V6 vs mechanical SCSI HDD here: https://68kmla.org/bb/index.php?thr...-devices-in-a-pci-powermac.31139/#post-331898

Final verdicts:

A Scsi2Sd V5 only outperforms the mechanical drive for random read/write, sequential is actually several times slower than the physical drive.

A Scsi2Sd V6 will outperform the mechanical drive ~4x in random read as well as Random write. Sequential read is 2x faster, but sequential write is down ~15%.

So unless you are writing a lot of data to disk to where 4.6M over 4.0M matters, a v6 is a substantial improvement over the stock hdd.
 
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