Thunderbolt 2 speeds with fast SSD

Started Jul 21, 2020 | Discussions
tsinsf Contributing Member • Posts: 871
Thunderbolt 2 speeds with fast SSD

I'm considered buying a fast (over 2800 mbs) external SSD combatible with Thunderbolt 3, for use with a future computer. At present my computer (2013 Mac  Pro) only has Thunderbold 2. My plans are to buy a new MAC when the latest chip iMac is available, so it will be awhile. Please correct me if I am not doing the math correctly. Thunderbold 2 supports 10 gbs data transfer, so it should easily be able to transfer and not slow down a current fast SSD, like 2880 or 3500 mb/s. Am I correct?

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graybalanced Veteran Member • Posts: 7,090
Re: Thunderbolt 2 speeds with fast SSD
1

tsinsf wrote:

I'm considered buying a fast (over 2800 mbs) external SSD combatible with Thunderbolt 3, for use with a future computer. At present my computer (2013 Mac Pro) only has Thunderbold 2. My plans are to buy a new MAC when the latest chip iMac is available, so it will be awhile. Please correct me if I am not doing the math correctly. Thunderbold 2 supports 10 gbs data transfer, so it should easily be able to transfer and not slow down a current fast SSD, like 2880 or 3500 mb/s. Am I correct?

No, it won't work that way. You have to keep your units straight, including capitalization.

The fast SSD is 2800MBs...that is megabytes (note capital B, if lower case it would be megabits)

Thunderbolt 2...10Gb/sec (gigabits since it is lower case)

Using an online converter, 10Gb/sec = 1250MB/sec, which is less half of the 2800+MB/sec of the best NVMe SSDs. That is why the answer is no. To use the full speed of a top of the line NVMe SSD, you need Thunderbolt 3, 40Gb/sec = 5000MB/sec.

The silver lining in your Mac Pro's Thunderbolt 2 (10Gb/sec) limit is that instead of paying top dollar for a 2880Gb/sec SSD you cannot fully use, you could save money with the lower grade but more affordable 1000-1200Gb/sec NVMe SSDs that Thunderbolt 2 can use most of.

(If the 2013 Mac Pro USB ports are the older 5Gb/sec kind, their limit is 625MB/sec, only good enough for a SATA SSD.)

Or you can buy that expensive 2880MB/sec SSD now, use it in a Thunderbolt 2 enclosure at no more than half its speed on your 2013 Mac, but be able to use its full speed when you buy a new Mac. But to get full speed in the future, you would have to move it from a Thunderbolt 2 enclosure to a Thunderbolt 3 enclosure. Or if you wait long enough that it will be several years before you get a new Mac, you could move it into a USB 4 enclosure. USB 4 will mostly match Thunderbolt 3 capabilities.

In daily use, due to overhead and other factors, the actual speed of I/O transfers is a lot lower. Most are probably under 500MB/sec. Meaning a cheap SSD is probably good enough for a 2013 Mac Pro, the benefits of faster SSDs will be much harder to notice for photo editing. Easier to notice with, say, 8K video editing.

bmoag Veteran Member • Posts: 3,203
Re: Thunderbolt 2 speeds with fast SSD

Theoretically. Certainly software tests will show impressive numbers.

Real world perception is something else. Hence if cost is not factor go for the "fastest" but the yields may not be worth the cost.

M2 drives can run at "mere" SATA speeds. Some will run slower than mechanical drives once the cache is saturated. The box enclosing the thing may have a thunderbolt connector but that does not mean it passes data at the maximum speed. One must do one's research.

Extended writes, as in copying gigabytes of data, can show perceptible benefits past standard SATA speeds. Many if not most writes are of a size that the end user can not perceive a difference between any type of storage media. There is a benefit to writing large image files to at least SATA SSDs but what the benefit is worth as storage costs go up may be in the imagination of the end user. Also it is difficult as an end user to distinguish rendering from write times in a lightly threaded program like PS.

Extended reads, as in booting a computer, benefit from faster speeds but to the end user the benefits past standard SSD speeds are generally less than overwhelming. Loading a very large file into PS benefits to a point from faster storage but that benefit does not progress linearly with the read speed of the media for many reasons.

The point is that except for niche uses there really is a point where measurable I/0 speeds are irrelevant to end user perception but to each her own.

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Huskywolf Regular Member • Posts: 262
Re: Thunderbolt 2 speeds with fast SSD

considering the price of SATA 2.5" SSD is not much cheaper than NVME SSD, I'd go with NVME with 3.1 Gen 2 (10Gbps) case. It's smaller but runs hotter.

OP tsinsf Contributing Member • Posts: 871
Re: Thunderbolt 2 speeds with fast SSD

Thank you so much. Your response was concise, and to the point. Very helpful information.

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noirdesir Forum Pro • Posts: 13,797
Re: Thunderbolt 2 speeds with fast SSD

graybalanced wrote:

tsinsf wrote:

I'm considered buying a fast (over 2800 mbs) external SSD combatible with Thunderbolt 3, for use with a future computer. At present my computer (2013 Mac Pro) only has Thunderbold 2. My plans are to buy a new MAC when the latest chip iMac is available, so it will be awhile. Please correct me if I am not doing the math correctly. Thunderbold 2 supports 10 gbs data transfer, so it should easily be able to transfer and not slow down a current fast SSD, like 2880 or 3500 mb/s. Am I correct?

No, it won't work that way. You have to keep your units straight, including capitalization.

The fast SSD is 2800MBs...that is megabytes (note capital B, if lower case it would be megabits)

Thunderbolt 2...10Gb/sec (gigabits since it is lower case)

Using an online converter, 10Gb/sec = 1250MB/sec, which is less half of the 2800+MB/sec of the best NVMe SSDs. That is why the answer is no. To use the full speed of a top of the line NVMe SSD, you need Thunderbolt 3, 40Gb/sec = 5000MB/sec.

That is all nice and well but Thunderbolt 2 (and the 2013 Mac Pro has TB 2) supports 20 Gbit/s or 2500 MB/s. That is still slower than the fastest NVMe SSDs but not that much anymore.

You can also buy an external Thunderbolt 3 SSD and use Apple’s TB 2 to TB 3 adapter to connect it to a computer with TB 1 or 2 ports (the same adapter also works in the other direction).

JPAlbert Senior Member • Posts: 1,209
Re: Thunderbolt 2 speeds with fast SSD

I'm not sure how many tbolt3 SSD drives are out there right now.
One I do know of is the Samsung X5... BUT... it seems to have problems with overheating under load, and as a result the speeds "throttle back". This was the subject of a thread over at macintouch.com.

Another problem is that it requires bus power to run, and the tbolt3 to tbolt2 adapter that Apple offers DOES NOT pass bus power "through". So the drive can't be used with older Macs that have tbolt2, unless you have an external thunderbolt dock that has a powered port.

So... I wouldn't buy a tbolt3 drive until I had a Mac capable of using it -- one that has tbolt3/USBc ports.

You're probably not going to get speeds quite as fast as 2800MBps.
You could see speeds in the 2100-2500+ range, however.

Tom_N Forum Pro • Posts: 20,276
Re: Thunderbolt 2 speeds with fast SSD

graybalanced wrote:

Or you can buy that expensive 2880MB/sec SSD now, use it in a Thunderbolt 2 enclosure at no more than half its speed on your 2013 Mac, but be able to use its full speed when you buy a new Mac. But to get full speed in the future, you would have to move it from a Thunderbolt 2 enclosure to a Thunderbolt 3 enclosure.

There are other, cheaper, options for connecting a M.2 PCIe NVMe SSD:

  1. Buy a TB 3 enclosure and a TB 3-to-2 adapter. (The Apple one, or some other one known to be bi-directional.)
  2. Buy a USB-C 3.1 Gen 2 enclosure. This should let you connect to non-TB-equipped Macs using USB-A, at USB 3.0 speeds. Later, you may be able to get faster speeds out of the M.2 SSD by moving it to a TB3 enclosure. (But you may find that speeds of a USB-C 3.1 Gen 2 / PCIe SSD are fast enough compared to those of a USB 3.0 / SATA SSD that you don't need to spend the money on that upgrade.)

Neither require you to use a TB2 enclosure, even temporarily.

graybalanced Veteran Member • Posts: 7,090
Re: Thunderbolt 2 speeds with fast SSD

noirdesir wrote:

That is all nice and well but Thunderbolt 2 (and the 2013 Mac Pro has TB 2) supports 20 Gbit/s or 2500 MB/s. That is still slower than the fastest NVMe SSDs but not that much anymore.

Good catch, I got it wrong...I forgot 10Gb/sec is for Thunderbolt 1. So NVMe on Thunderbolt 2 is somewhat more practical than I stated earlier.

jf_tea Senior Member • Posts: 1,577
practicalities

Many new techno gadgets are *great* -- in theory.

I had a 500 GB Samsung EVO SSD (SATA) in a 4 bay OWC Thunderbolt 2 enclosure. I've used it at first with a 2011 27" iMac, with Thunderbolt. And, then with a 2015 iMac Retina, with Thunderbolt 2. Neither iMac had an internal SSD. So, I never did a external SSD to internal SSD copy. Reads from SSD to RAM were blazingly fast: starting an app or opening a RAW file. I think Activity Monitor did show reads peaking at about 300+ MB/s. Transfers from a HDD to the SSD (both in the Thunderbolt 2 enclosure) were at about 250+ MB/s (peak). And from SSD to HDD (HDD writes) the peak write speed was at 210 MB/s (large files to a 6TB or 10 TB HDD).

The internal SSD in my 2019 MBP 13 inch can do burst transfer about 10 times faster, but, this get to a bottleneck when transfering to anything outside of the MBP.

Also, don't plan too far in the future as technology changes quite quickly.

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-JF

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RodandEva Regular Member • Posts: 249
Re: Thunderbolt 2 speeds with fast SSD

I recently went through the same mental exercise, I have a 2013 MBP with TB1 ports,  but plan to upgrade at some point in the future. I ended up with an OWC NVMe TB3 enclosure, has four slots and up to 8TB in total. The other advantage of NVMe enclosures vs SATA is that they are much smaller. And, the SATA enclosure would not have really saved me much in $’s.

The OWC enclosure is great, but a little louder than I would like due to the fan.

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Daverich04 Regular Member • Posts: 156
Re: Thunderbolt 2 speeds with fast SSD

RodandEva wrote:

I recently went through the same mental exercise, I have a 2013 MBP with TB1 ports, but plan to upgrade at some point in the future. I ended up with an OWC NVMe TB3 enclosure, has four slots and up to 8TB in total. The other advantage of NVMe enclosures vs SATA is that they are much smaller. And, the SATA enclosure would not have really saved me much in $’s.

The OWC enclosure is great, but a little louder than I would like due to the fan.

I just returned an OWC Express 4M2 M.2 NVMe SSD Enclosure. I put 4 Samsung 970 EVO Plus drives in it and got half the advertised transfer speeds when plugged into the TB3 ports on my 2020 Mac Mini. Plus the noisy fan you mentioned.

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