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Sharky II

macrumors 6502a
Original poster
Jan 6, 2004
692
47
United Kingdom
Hi,

I've just purchased a PCIe card to give me 2x USB 3.1 gen 2 ports.

I've also purchased a Crucial 1TB SATA III traditional SSD, and an enclosure that supports SATA III drives but operates at USB3.1 Gen2 speeds. I understand the bottleneck is the SSD's SATA III spec, but that the USB3.1 Gen2 enclosure & PCIe card should give me as close to maximum SATA III speeds as possible, and should out perform an identical drive that were plugged into one of the internal SATA II ports.

My question is - is there a circumstance whereby connecting the drive to the internal SATA II ports could give improved performance?

I'm wondering specifically about the CPU overhead of using USB drives, as well as latency performance. Or are these factors a thing of the past, from the USB2 days?

I know that Blackmagic Speed Test results don't give the entire picture.

I plan to use this drive to run extremely large audio/Logic X projects at 24/96khz that are currently struggling on a 2TB WD Black 7,200rpm, and probably some 4K FCPX projects, running Panasonic GH5 files. I also plan to buy a 1TB NVME and suitable caddy in the future to get even faster speeds, and use it on the second port of the USB3.1g2 card to get (up to) 10mbps throughput.

Thanks!

Ed

(Current Machine Spec: 4,1 -> 5,1, 12 x 3.46GHz, 48GB, PCIe AHCI SSD boot drive, Firmware 140.0.0, 10.3.6 currently, will grab RX 580 8GB soon and upgrade to Mojave)
 
Last edited:

Sharky II

macrumors 6502a
Original poster
Jan 6, 2004
692
47
United Kingdom
Ah, a good point to consider, thank you. What confuses me about this is that certainly lots of nMP, iMac, MBP etc users will be using USB3 for lots of their data, without major catastrophes.

As this is USB3.1 Gen2, similar to Thunderbolt 1, which does allow TRIM to be enabled (as I best recall), is anyone able to tell us if you've tried this kind of setup and if TRIM works?

I guess I'll find out tomorrow when the stuff arrives, and I'll report back. TRIM is enabled for my internal PCIe SSD and another SATA III SSD simply plugged into the DVD bay SATA II port.

I'm mainly wondering if the USB3.1gen2 spec is superior in every way to SATA II or not :)

Thanks!
 

Sharky II

macrumors 6502a
Original poster
Jan 6, 2004
692
47
United Kingdom
So, got the gear today. These are the results of SATAII vs USB3.1gen2 - around double, as expected.

Under the 'USB' category of System Information, there is no option for TRIM, so... I guess that's that, unless anyone has any further light they could shed?!
 

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Sharky II

macrumors 6502a
Original poster
Jan 6, 2004
692
47
United Kingdom
Some 'real world' testing (copying some large applications over) in case anyone is interested:

I have a 500GB MX500 on the internal SATA II bus, about 80% full.

I have a 1TB MX1000 which is empty and connected via the USB3 connection and theoretically limited by the drive's SATA III speed.

Copy over Ableton Live 10 (3.64GB)

- 500GB SSD SATAII: 40-41 secs
- 1TB SSD USB3: 34 secs

Copy over 8x Applications 22.77GB total (Ableton Live 9 Suite / Ableton Live 10 Suite / Final Cut Pro / Motion / Logic Pro X / Logic Pro X.zip (backup) / Aperture):

- 500GB SSD SATAII: 3min 35 secs
- 1TB SSD USB3: 3min exactly

So, nowhere near 2x as fast, I would bet that 2x SSDs internally in software RAID0 could be faster and more reliable. And no bluetooth problems. The 500GB drive was actually 80% full and larger drives are usually faster. Could just be my USB3 card, my drive, my caddy etc... but thought it might be interesting to share.

Okay, better do some ACTUAL work now...

Cheers,

Ed
 

h9826790

macrumors P6
Apr 3, 2014
15,399
7,677
Hong Kong
Some 'real world' testing (copying some large applications over) in case anyone is interested:

I have a 500GB MX500 on the internal SATA II bus, about 80% full.

I have a 1TB MX1000 which is empty and connected via the USB3 connection and theoretically limited by the drive's SATA III speed.

Copy over Ableton Live 10 (3.64GB)

- 500GB SSD SATAII: 40-41 secs
- 1TB SSD USB3: 34 secs

Copy over 8x Applications 22.77GB total (Ableton Live 9 Suite / Ableton Live 10 Suite / Final Cut Pro / Motion / Logic Pro X / Logic Pro X.zip (backup) / Aperture):

- 500GB SSD SATAII: 3min 35 secs
- 1TB SSD USB3: 3min exactly

So, nowhere near 2x as fast, I would bet that 2x SSDs internally in software RAID0 could be faster and more reliable. And no bluetooth problems. The 500GB drive was actually 80% full and larger drives are usually faster. Could just be my USB3 card, my drive, my caddy etc... but thought it might be interesting to share.

Okay, better do some ACTUAL work now...

Cheers,

Ed

Applications are mainly consists of small files, if you want to see that 2x speed, you have to copy a single large file.

When you copying small random files. The limitation is the random read speed. Which can be way below the SATA II limitation.

Since your test was actually mixing small files with some “large enough” files. And with a better SSD. That’s why you can still see some improvement, but nowhere near 2x.

Think in this way, your Ableton Live 10 folder just 3.64GB.

For SATA II, speed limit is 250MB/s. Which means 4 seconds for 1GB.

With that speed, you only need ~15 seconds to copy 3.64GB. But the reality is, 40s. So, the main bottleneck isn’t the SATA II bandwidth limit (for this particular test / real world usage), but something else (e.g. the random speed limit from the SSD itself)

That’s why further double the bandwidth won’t help much.
 
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