Slow Read speed on External SSD

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Level 1

15 points

Slow Read speed on External SSD

Hi,

I got an Asus ROG Strix Arion NVMe SSD enclosure and a Sabrent Rocket Q 2TB yesterday and I'm using a base 16" MBP running Catalina 10.15.3.

Set it up and the write speeds seem to be around what I expect, but the read speeds in Blackmagic disk test are around the 170-180Mbps mark which is significantly slow considering it uses the USB 3.2 Gen 2 interface. I had split it into two partitions; one HFS+ and the other NTFS (I have Paragon NTFS installed so used Disk Utility to create both on a GUID Partition map.). It's odd because all the issues I've found online are for write not read.

I booted into Windows, installed CrystalMark and ran that on the NTFS partition and that scored just over 1050Mbps on read. Same Mac, same port and same cable, so it cannot be hardware related otherwise the change of OS wouldn't make a difference.

I've completely wiped the drive and set it up with just a single HFS+ partition and tested again, same result as before. I've also tested using the ports on both sides of the Mac as well. I'm at a bit of a loss as to what is making the difference in Catalina.

Any ideas on what might be causing this and how I might resolve it?

MacBook Pro 16", macOS 10.15

Posted on Mar 9, 2020 2:29 PM

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Answer 1

Top-ranking reply

runebinder Author

Level 1

15 points

Mar 10, 2020 12:54 PM in response to woodmeister50

Good idea, unfortunately I've already identified the issue now. It's the Sabrent SSD. Got a 512GB Samsung SM961 NVMe SSD in my desktop PC, so I decided to try that in the enclosure and test on the Mac and I'm getting over 900Mbps on both read and write which is more in line with what I expected.

So it must be something about the Psion controller that macOS does not like. I did read that Sabrent have done something weird in that it uses 4K sectors and no 512 Byte emulation meaning you can't clone them and I'm wondering if that could have something to do with the poor read speed.

They have a drive tool kit that lets you change to 512, unfortunately my Desktop is failing to boot to Windows whilst it is in the enclosure, and the tool kit doesn't recognise the Sabrent drive when it's in the enclosure. Got an old Z170 mobo that only has one M.2 slot so it would appear that I'm in a bit of a catch 22 situation.

Looks like my PC will be getting larger storage and I'll be using a smaller external SSD for now.

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Answer 2

Mar 10, 2020 9:11 AM in response to runebinder

Just as a quick test to verify that it is not an app bug,

if you a a single very large file on the drive, 4-5 GB should

suffice, open Activity Monitor, set it to Disk and while

watching the data rates in the lower right hand corner,

drag the file from the external drive to somewhere on the

internal drive. See what data rate that yields.

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Answer 3

runebinder Author

Level 1

15 points

Mar 15, 2020 3:50 AM in response to shaif-ali

Hi. it's plug and play and doesn't need drivers.

I have had an issue on Macs before when USB sticks have got corrupted and show a far smaller partition size than what it should be, what you're describing sounds similar. Potentially the drive itself may have failed.

Can you connect it to a Windows PC and see what it shows there? I'd also try running a SMART test on it in case it has failed and you need to return it for an exchange.

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Answer 4

Mar 15, 2020 1:14 AM in response to runebinder

Hey I just got this device too but I cant seem to access my storage, I got an intel 665p I think I might have messed up because I instantly formatted it after plugging it in now it just shows an empty 1gb drive instead of a 1tb drive. When you set it up did you have to install any drivers?

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Answer 5

Kappy

Level 10

362,007 points

Mar 9, 2020 9:12 PM in response to runebinder

You have not posted anything about the specs for your enclosure and the SSD. Nor have you indicated whether you are using a proper cable. The Asus enclosure may not be Mac compatible. You may want to use a different enclosure such as the Sabrent EC-NVME. The enclosure supports 10Gbps transfer rate over TB3. If you wish to get 40Gbps performance, assuming the SSD can support that speed, then expect to pay lots for an enclosure. The Semoic Thunderbolt 3 M.2 NVME Enclosure SSD Box NVME to Type-C Aluminium USB 3.1 40Gbps M.2 PCIE SSD Case from Amazon fully supports 40Gbps but the cost is around $112.00 USD.

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Answer 6

runebinder Author

Level 1

15 points

Mar 9, 2020 11:49 PM in response to Kappy

"You have not posted anything about the specs for your enclosure and the SSD" Yes I have, as said in the OPIt's USB 3.2 Gen 2 and using NVMe internally, the drive itself is an NVMe SSD and I included the make and model so not all that difficult to have looked that up.

Asus state that it is Mac compatible, I wouldn't have posted without checking basics like that out, and if I wasn't using a proper cable I would not be getting the correct speeds when booted into Windows via Bootcamp as stated in my OP. As mentioned it musty be something in macOS.

I'm not after a TB3 enclosure as I want compatibility with my desktop, I just want the read speeds I expect from USB 3.2 Gen 2 which I'm getting on the Mac if I boot into Windows.

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