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Topic starter
The current Thunderbay-SoftRAID SSD implementation advertises speeds of approx 1.3 GB/s for RAID 0 with the SSDs that can be purchased along with the Thunderbay drive. I am wondering about potential performance with other SSDs. Specifically, it seems pretty common these days for SSDs to advertise read/write of approx 0.5 GB/s. In theory, I would think then that with four of these in a RAID 0 array in the Thunderbay enclosure, one would anticipate r/w of arpprox 2.0 GB/s. Likewise, for RAID 5, I'd anticipate r/w of approx 2.0 / 1.5 (respectively).
Is this reasoning off? Is there some reason to not expect performance in this range when building with SSD components individually reading and writing at 0.5 GB/s? If it is off, what would be the causes and is there a reliable way to estimate performance ahead of time?
For reference, I'm operating on a Mac Pro 6,1 (late 2013), 64 GB ram, E5 processor with 6 cores x 3.5 GHz each.
Posted : 13/12/2016 5:31 pm
Yes your reasoning is off. Thunderbolt has a practical limit of about 1.4GB/s. You cannot send more over the bus, as 50% of Thunderbolt bandwidth is reserved for video signals. Your SSD's could be infinitely fast, and throughput would be bottlenecked by Thunderbolt 2 at 1.4GB/s.
Thunderbolt 3 is theoretically much faster, and while we have not tested it yet, should easily surpass the 2GB/s you desire. Its possible Thunderbolt 3 can achieve throughput close to 3GB/s. Until we have some examples in our labs, however, we can't be more definitive.
Posted : 14/12/2016 7:10 pm
Topic starter
Ok, this is helpful. I had thought that the OWC Thunderbay connected to the computer with two thunderbolt cables, but actually it looks like instead it just connects with one such cable and then provides two additional thunderbolt plugs to connect in other things.
Have you by chance tried the setup (e.g. RAID 0) using two of the OWC Elite Pro Duals? It would seem then that this could double that thunderbolt bottleneck and thus be able to get to 2.0 GB/s with four 500 GB/s SSDs? Or am I missing something again?
Thanks
Posted : 15/12/2016 2:29 pm
All Thunderbay enclosures have exactly 2 Thunderbay ports, one for connecting to the computer and one to plug another device into. None have 3 ports! But you can daisy chain multiple enclosures.
If you have a Mac Pro 6,1, and connect each Dual into a separate Thunderbolt bus (there are three buses, but 6 ports!), then yes you can get up to 2400MB/s.
No other Mac model has independent Thunderbolt buses, however.
Posted : 15/12/2016 4:10 pm
Topic starter
Ok, got it, thanks. But, if the regular Thunderbays (that take four disks) have two thunderbolt ports, can I just plug both of those into the pro? That's what I had originally envisioned doing. . .
Posted : 15/12/2016 4:15 pm
No, the two ports are one in, one out. They can only be connected one port to a computer, the other to another box.
Give up on that idea.
Posted : 15/12/2016 5:00 pm
Topic starter
Have you folks tested out the new USB 3.1 (gen 2) hard drive enclosures? I'm wondering, for instance, if something like this ( https://smile.amazon.com/Siig-SATA-External-Drive-Enclosure/dp/B00YT6TOJO/ref=sr_1_3?ie=UTF8&qid=1482343433&sr=8-3&keywords=usb+3.1+gen+2+enclosure) plus a USB-C to Thunderbolt 2 converter would enable me to get to around 2.0 GB/s with RAID 0 + 4 500 GB/s SSDs?
If you have done such tests, do you have specific recommendations or considerations for USB 3.1 gen 2 enclosures?
Posted : 21/12/2016 1:58 pm
Any disk that is reliable in OS X, will be reliable when used with SoftRAID.
With USB 3.1 and USB C, stick to "brand name" companies, as USC does not have to pass any certification tests, unlike Thunderbolt enclosures. Thunderbolt will always be a better option if you have the choice between any flavor of USB and Thunderbolt (such as Thunderbolt 3 and USB 3.1)
Posted : 23/12/2016 2:23 pm
