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Umm... someone is definitely math-challenged.
Definitely. It looks like he took the hard disk drive's power (1.875W) and divided it by the SSD's power (0.833W). 1.875/0.833 = 2.25. That number implied an English statement like "the hard disk drive consumes 2.25x as much power as the SSD" or (if you divide the SSD by the hard disk drive) "the SSD consumes 44% of the hard disk drive's power".

If you want to write "x saves y% over z", then you need to compute the difference between the two (z - x) and divide that by the baseline (what you're saving over, in this case z). With the numbers from the article, that means (1.875 - 0.833)/1.875 = 1.042/1.875 = 0.556. The SSD saves more than 55% over the hard disk drive, not "more than 225%".
 


Ric Ford

MacInTouch
A trap to beware when ordering M.2 SSD's:

The M.2 format accomodates both slow SATA and fast NVMe SSDs, which look virtually identical with confusingly similar connectors, such that a SATA M.2 SSD may fit into an NVMe slot but not work.

But let's add to the confusion even more:

WD "Blue" M.2 SSDs come in both NVMe and SATA versions that are very easily mixed up, given their identical names and appearance. In addition, the capacities appear to be different, where 1TB and 2TB models are available in SATA versions but not NVMe versions, at least at Amazon, where it is easy to confuse the two.

After making this mistake with a Sabrent USB-C NVMe enclosure, the SSD never appeared as a storage volume (for formatting, etc.), but the enclosure's internal JMicron controller did appear in System Information under the USB section.
 


The M.2 format accomodates both slow SATA and fast NVMe SSDs, which look virtually identical with confusingly similar connectors, such that a SATA M.2 SSD may fit into an NVMe slot but not work.
It's worse than that. If it was just a matter of the different "keyings" on the connector, it would be easy to spot mismatches because they wouldn't physically fit into the connector.

Within each keying, the connector supports multiple interfaces (e.g. an M-keyed device may be PCIe x4, SATA or SMBUS). Looking at the pinouts, it appears that there is no conflict - PCIe, SATA and SMBUS use different pins. This was probably designed to allow a host to support multiple types of devices on one connector (with a few "config" pins so a device can identify its capabilities to the host).

Unfortunately, it is clear that hosts that support multiple interfaces on the port are few and far between. So you need to be careful (as you pointed out) to get a device that matches what the host expects. And even if you have a host that supports multiple interfaces, that would only ensure that the device runs - you'd still have a serious performance problem if you were shopping for a PCIe device and bought a SATA one by mistake.
 


A trap to beware when ordering M.2 SSD's
Add this one: I delegated ordering two new Samsung NVMe 1TB SSDs as cache drives for our new Synology to my co-worker, who handles the business Amazon account. I thought I'd been clear, NVMe, Samsung, !TB, but Amazon search for those phrases tossed her a set of SATA M.2 SSDs, which don't meet the Synology specification. Fortunately, I was able to "blame" Amazon search results for the incorrect purchase, and return shipping was free.

I once called Amazon to complain about how fuzzy their results often are, no matter how carefully they're narrowed down by detailed model numbers, etc., and was told, in corporate speak, it's intentional, to show customers options...
The M.2 format accomodates both slow SATA and fast NVMe
Mentioned before, when I bought the first three 2015 NUCs, I bought the fastest M.2 SSDs, which were the new NVMe type. They do work in the NUCs, but not at NVMe speeds. SATA M.2 SSDS also work. That both types work in these NUCs in the same connector doesn't imply compatibility beyond those particular computers....
 


Add this one: I delegated ordering two new Samsung NVMe 1TB SSDs as cache drives for our new Synology to my co-worker, who handles the business Amazon account. I thought I'd been clear, NVMe, Samsung, !TB, but Amazon search for those phrases tossed her a set of SATA M.2 SSDs, which don't meet the Synology specification. Fortunately, I was able to "blame" Amazon search results for the incorrect purchase, and return shipping was free.
I've learned that when specifying something for someone else to order, send them a link directly to the product. Don't know if that would have worked in your case, but I've found it has eliminated 98% of search/selection errors for me. I still get people clicking on other product links that appear on the product page on most sites but far less than if I specify an item search. Cheers.
 


Ric Ford

MacInTouch
Here's a 1TB Samsung 970 EVO NVMe SSD in a 10Gbps Sabrent USB-C NVMe enclosure1. 2., connected to the 2017 iMac 5K's USB-C port... I can't see SMART data for this enclosure, either with macOS 10.12 Sierra or macOS 10.14 Mojave —I tried DriveDX, Disk Sensei, SoftRAID and SMART Utility. Trim doesn't seem to be enabled, either.
I cannot see SMART data when I move the SSD to a Fledging Shell enclosure, either. This seems to be an issue with the enclosure/controller/driver, because Samsung 970 EVO specs list both SMART and Trim as being supported.
 


I cannot see SMART data when I move the SSD to a Fledging Shell enclosure, either. This seems to be an issue with the enclosure/controller/driver, because Samsung 970 EVO specs list both SMART and Trim as being supported.
Apparently, only a subset of a storage device's parameters are available over USB. A few months ago, I moved four spinning hard drives from a USB enclosure to a Thunder3 QuadX Thunderbolt 3 enclosure. Although "aware" of the existence of the Thunderbolt bus, my Mac now talks (more or less) directly to the hard drives' SATA interface. One of the benefits to this is that APFS works absolutely wonderfully. Over USB, APFS was a masochistic nightmare. Besides that, the raw speed over Thunderbolt 3 is just amazing and, of course, SMART works just fine.

The Thunder3 QuadX has a second Thunderbolt 3 port. Both are powered at 20W. I plugged a Fledging NVMe into the second port with a 2TB Sabrent SSD. So now, wow! 32 TB of spinners and 2 TB of SSD (with TRIM) over one bus. It's like having a new machine. And it just works!

Maybe not exactly correct, but I look at it as connecting to individual devices over a Thunderbolt bus, whereas with USB you are connecting to generic "USB storage". Definitely cheaper and has its place, but nothing like Thunderbolt, billed as extending the PCI bus, which appears to be true to me.
 


Ric Ford

MacInTouch
Apparently, only a subset of a storage device's parameters are available over USB....
While that may be true, I'm used to seeing full SMART data over USB (with the SAT SMART driver installed and SATA devices in the USB enclosures). Something's different and broken with the USB-NVMe enclosures/controller/software.

Thunderbolt 3 has lots of advantages over USB, especially in performance, but it's awfully expensive by comparison, and there have been reliability problems with it, too, as well as compatibility problems with older systems (e.g. requiring a powered dock and adapter).

If you have the money and compatible ports, and portability isn't an issue, and you aren't experiencing data integrity issues, then Thunderbolt 3 should be great. :-)
 


While that may be true, I'm used to seeing full SMART data over USB (with the SAT SMART driver installed and SATA devices in the USB enclosures). Something's different and broken with the USB-NVMe enclosures/controller/software.
I'd never heard of SAT SMART and had to search for it. Pretty interesting and might be useful on an old Snow Leopard machine I keep running. Thanks for that. The GitHub development site does point to a list of compatible/incompatible enclosures (www.smartmontools.org). which doesn't claim to be exhaustive. I see four Sabrent and no Fledging enclosures there. None appear to be the ones you are talking about, so maybe yours are just incompatible, not broken.
 


... Thunderbolt 3 has lots of advantages over USB, especially in performance, but it's awfully expensive by comparison, and there have been reliability problems with it, too, as well as compatibility problems with older systems (e.g. requiring a powered dock and adapter). If you have the money and compatible ports, and portability isn't an issue, and you aren't experiencing data integrity issues, then Thunderbolt 3 should be great. :-)
Oh, it certainly is great. I recently purchased a 1TB NVMe SSD in a Thunderbolt 3 enclosure from macsales.com. I connected it to my 2017 5K 27" iMac's Thunderbolt 3 port, and the throughput is utterly amazing. Using Blackmagic's Speed Test, I get around 1600 MB/s write speeds and 2300 MB/s read speeds, which makes the iMac's internal 7200-rpm hard drive/ 32GB SSD "fusion drive" laughable. You can well imagine which is my boot drive!
 


Ric Ford

MacInTouch
I recently purchased an 1TB NVMe SSD in a Thunderbolt 3 enclosure from macsales.com. I connected it to my 2017 5K 27" iMac's Thunderbolt 3 port, and the throughput is utterly amazing. Using Blackmagic's Speed Test, I get around 1600 MB/s write speeds and 2300 MB/s read speeds, which makes the iMac's internal 7200-rpm hard drive/ 32GB SSD "fusion drive" laughable. You can well imagine which is my boot drive!
Here are some Samsung X5 benchmarks and Samsung 970 EVO tests for comparison.

I'm still a little concerned about longevity and thermal throttling when using a portable Thunderbolt 3 SSD for intensive applications (e.g. as the boot drive). Alternatives, such as the Thunderbolt 3 RAID enclosures and Thunderbolt 3 PCIe enclosures, might provide better cooling longevity, and even performance, depending on their details. In addition, self-powered Thunderbolt 3 enclosures should be compatible with older Macs via Apple's Thunderbolt 3-to-Thunderbolt 2 [Mini DisplayPort] adapter (with more limited performance).
 


Here are some Samsung X5 benchmarks and Samsung 970 EVO tests for comparison.
I'm still a little concerned about longevity and thermal throttling when using a portable Thunderbolt 3 SSD for intensive applications (e.g. as the boot drive). Alternatives, such as the Thunderbolt 3 RAID enclosures and Thunderbolt 3 PCIe enclosures, might provide better cooling longevity, and even performance, depending on their details. In addition, self-powered Thunderbolt 3 enclosures should be compatible with older Macs via Apple's Thunderbolt 3-to-Thunderbolt 2 [Mini DisplayPort] adapter (with more limited performance).
Yes, longevity remains the question. As for thermal throttling: I haven't seen it. Yet. Not only is it my Mojave boot drive, but I also run Linux VMs from the drive at the same time and have not seen any appreciable throttling. Then again, I haven't really measured it in-depth yet. I do know that the macsales/OWC drive does not have a fan.
 


Ric Ford

MacInTouch
Yes, longevity remains the question. As for thermal throttling: I haven't seen it. Yet. Not only is it my Mojave boot drive, but I also run Linux VMs from the drive at the same time and have not seen any appreciable throttling. Then again, I haven't really measured it in-depth yet. I do know that the macsales/OWC drive does not have a fan.
You should be able to see temperatures in the SMART data (something I couldn't do with the USB-C NVMe enclosures I tried, which weren't providing SMART data).

It might be interesting to run a couple of quick benchmarks after using the drive heavily and having it heated up, to see if they differ from results with a "cold" SSD.
 


Ric Ford

MacInTouch
I cannot see SMART data when I move the SSD to a Fledging Shell enclosure, either. This seems to be an issue with the enclosure/controller/driver, because Samsung 970 EVO specs list both SMART and Trim as being supported.
This seems to describe the problem with SMART data and NVMe-USB bridges/controllers:
smartmontools said:
USB devices and smartmontools
To access USB storage devices, the operating system sends SCSI commands through the USB transport to the device. If the USB device is actually a (S)ATA or NVMe drive in an USB enclosure, the firmware of its USB bridge chip translates these commands into the corresponding ATA or NVMe commands. This works straightforward for read and write commands, but not for SMART commands.

To access SMART functionality, smartmontools must be able to send native ATA or NVMe commands directly to the drive. For USB devices, at least the following conditions must be met:
  • The USB bridge provides an ATA or NVMe pass-through command.
  • This command is supported by smartmontools.
  • The operating system provides a SCSI pass-through I/O-control which works through its USB-layer.
  • SCSI support is implemented in the operating system interface of smartmontools.
Many recent USB to SATA bridges support the pass-through commands from the SAT (SCSI/ATA Translation, ANSI INCITS 431-2007) standard. Other USB bridges provide vendor specific pass-through commands. The NVMe SCSI Translation Reference does not yet specify a pass-through command for NVMe.
 


You should be able to see temperatures in the SMART data (something I couldn't do with the USB-C NVMe enclosures I tried, which weren't providing SMART data). It might be interesting to run a couple of quick benchmarks after using the drive heavily and having it heated up, to see if they differ from results with a "cold" SSD.
I may well do that in the near future, Ric. I'll provide data once I do, if you're interested.
 


Problem with SSD and OWC enclosure:

I recently upgraded my Early 2015 MacBook Air 13-inch with a Samsung 970 EVO 500GB NVMe M.2 SSD. It required this Sintech adapter. So far, so good. It has been working fine since January of this year.

My second step was to purchase the OWC enclosure to be able to utilize the 256GB Apple-branded SSD that was shipped with the MacBook Air. If my memory is correct, it worked properly exactly once. After a power-down and re-start I immediately got error messages that the drive was no longer bootable, that it had errors, and that I should copy any data that I could from it and erase and start over.

I tried Disk Utility and it indicated it could not repair the disk, it had a "disk full error", and the disk had been converted to read only. I did as suggested - used Disk Utility to re-format. I put some files on it and, surprise, after a power cycle, it was the same set of error messages all over again.

I had a hunch that this was some sort of incompatibility between HFS and the formatting scheme being used by Mojave. I also thought that perhaps Apple would at least make the new [macOS] compatible with Windows FAT, so I formatted again using ExFat, and at least that works.

Has anyone seen this sort of problem, and is there a better solution? Many thanks to the experts here at MacInTouch.
 


Ric Ford

MacInTouch
My second step was to purchase the OWC enclosure to be able to utilize the 256GB Apple-branded SSD that was shipped with the MacBook Air. If my memory is correct, it worked properly exactly once. After a power-down and re-start I immediately got error messages that the drive was no longer bootable, that it had errors, and that I should copy any data that I could from it and erase and start over.... Has anyone seen this sort of problem, and is there a better solution? Many thanks to the experts here at MacInTouch.
This sounds like something you should check with OWC Support. (Please let us know what you find out.)
 


Oh, it certainly is great. I recently purchased a 1TB NVMe SSD in a Thunderbolt 3 enclosure from macsales.com. I connected it to my 2017 5K 27" iMac's Thunderbolt 3 port, and the throughput is utterly amazing. Using Blackmagic's Speed Test, I get around 1600 MB/s write speeds and 2300 MB/s read speeds, which makes the iMac's internal 7200-rpm hard drive/ 32GB SSD "fusion drive" laughable. You can well imagine which is my boot drive!
It is for this reason I am not so quick to dismiss recommending a 27" iMac with a Fusion Drive in particular circumstances. As long as we are easily able to boot from an external drive of reasonable speed, the internal Fusion Drive can be used for user data or as archival storage. Should Apple take away the ability to easily boot from an external volume, as it it seems they are doing with T2-equipped Macs, I see no reason for their existence.
 


It is for this reason I am not so quick to dismiss recommending a 27" iMac with a Fusion Drive in particular circumstances. As long as we are easily able to boot from an external drive of reasonable speed, the internal Fusion Drive can be used for user data or as archival storage. Should Apple take away the ability to easily boot from an external volume, as it it seems they are doing with T2-equipped Macs, I see no reason for their existence.
I have a 2019 MacBook Pro which has the T2 chip and I boot from external drives all the time. Initially you cannot. But after interrupting normal startup with the Command-R keys you can change that.

If they ever do completely away with booting from an external drive, a lot of people are going to be pissed.
 



This sounds like something you should check with OWC Support. (Please let us know what you find out.)
I spoke with technical support at OWC, and this is not a problem that they had heard of. They did concede that, quoting approximately, large files, especially incompressible data generally from videographers could mess up the directory structure.

I did have virtual hard disk files for VirtualBox on the drive. Is that the type of file they are referring to, I wonder?

Also, as I searched around on the OWC site I found this technical bulletin:
Relevant Part Number: OWCMAU3ENPRPCI

Please note that the SSDs which Apple supplied with some of its computers are not compatible with the OWC Envoy Pro (OWCMAU3ENPRPCI). They work only when installed in the Mac model(s) they were designed for. At the time of this writing the only machines potentially affected will be the MacBook Air 7,2 | MacBook Pro 11,4 | MacBook Pro 11,5 | MacBookPro12,1 — these computers ship with SSDs that may not be compatible with any OWC Envoy Pro (PCIe) enclosure.
Now that the original Apple SSD is no longer in the MacBook Air, I have no way, that I know of, to determine if it is one of the SSDs that "may not be compatible".
 


They did concede that, quoting approximately, large files, especially incompressible data generally from videographers could mess up the directory structure.
I'm generalizing here without trying to look up the specifics of your SSD. The SSDs OWC sold when I bought one were based on the Sandforce controller that compressed files "on the fly" as they were written... There's quite a variety of files that can't be compressed because they already are compressed — video, jpg, pdf, even the guts of a Microsoft Word .docx is a zip.

Sending a huge already compressed video file "through" a "compressing" drive controller that's processing other reads/writes simultaneously does seem a possible source of problems.

I've copied VM files around, and they are big. I've always presumed they're somewhat analogous to applications on Mac that are packages which present as folders. Maybe someone else with real knowledge can clarify.
 


... Also, as I searched around on the OWC site I found this technical bulletin:
Relevant Part Number: OWCMAU3ENPRPCI
Please note that the SSDs which Apple supplied with some of its computers are not compatible with the OWC Envoy Pro (OWCMAU3ENPRPCI). They work only when installed in the Mac model(s) they were designed for. At the time of this writing the only machines potentially affected will be the MacBook Air 7,2 | MacBook Pro 11,4 | MacBook Pro 11,5 | MacBookPro12,1 — these computers ship with SSDs that may not be compatible with any OWC Envoy Pro (PCIe) enclosure.
And just going to their site now, they still will sell you one for those models!
 


I spoke with technical support at OWC, and this is not a problem that they had heard of. They did concede that, quoting approximately, large files, especially incompressible data generally from videographers could mess up the directory structure.
I did have virtual hard disk files for VirtualBox on the drive. Is that the type of file they are referring to, I wonder?
Typically, no. As later posters in this thread have mentioned, large files that are already compressed defeat the compression-speedup capabilities of the Sandforce controllers. But VM disk image files are typically not compressed, and are typically highly compressible. I don't think that's the issue you're seeing.
 


... MacBook Air 7,2
Now that the original Apple SSD is no longer in the MacBook Air, I have no way, that I know of, to determine if it is one of the SSDs that "may not be compatible".
Actually, you don't need the Apple SSD in the MacBook Air. Just go to "About this Mac" at the apple menu, click on "System Report", and look at the number at "Model Identifier: #,#", as the number is not dependent on the SSD but the computer model.
 


... You could get an external SSD but at what cost? A backup drive needs high capacity; at least as large as the Fusion drive you're cloning. What we need is an SSD/hard disk drive combo in an enclosure that could be mounted as an external Fusion drive. Does such a thing even exist?
"Out of the box"? No, but it could be cobbled together. First, there are multiple-drive enclosures. Three examples Akitio NT U31C or OWC Mercury Elite Pro Duo Mini or Thunderbay 4.

Fill one bay with an SSD and the other with hard disk drive. They'd need to be in a mode where they present as independent disks (may need to avoid enclosures where only one of the bays is bootable when in independent disk mode — that may knock out some of the examples above).

Second, there is a command line diskutil APFS subset command, e.g.

disktutil apfs create device /dev/disk4 /dev/disk5 newFusionDisk

which should create a new Fusion disk, if those are recognized as two different kinds of drives (e.g., disk4 is an SSD and disk5 is a hard disk drive). ('apfs create device' is a compound of 'createContainer" and 'create volume'.) Again, the enclosure needs to present the SSD as an SSD.

There is no GUI interface for doing this. There is probably not one coming in the future, either.

A backup and a "production" (fast) bootable drive are really two different roles. If your primary drive died and you can get anything up and running at any speed in 3-5 minutes, that is better than nothing. Lots of large-scale disaster recovery operations run at diminished capacity. That isn't necessarily a flawed state for a given budget.

I wouldn't be surprised if "home grown" Fusion drives with better SSD:hard disk drive ratios didn't better than the stuff that Apple sells. If the SSD is sub-10% caching and you have this widespread colocation of metadata and user data, then a bigger cache probably works better. Apple is controlling costs with their Fusion drive configs, not focusing on performance. So if you make the external Fusion drive have twice as much capacity (so it can hold more snapshots or volumes), then it's probably a reasonable idea to make the SSD bigger as you make the hard disk drive bigger. Having high performance 'fail over', though, is going to cost substantively more.
 


Ric Ford

MacInTouch
Both portable SSDs and large-capacity, fast thumb drives offer a way to back up securely when away from home, without the Cloud.
I no longer use "thumb" drives, because real SSD prices have dropped so much, while they're far more reliable (with built-in error-correction missing from "thumb" drives) and far faster, as well. And they're very compact, as well, nowadays (e.g. Samsung T5).
 


I no longer use "thumb" drives, because real SSD prices have dropped so much
With 2.5" SATA SSDs so very cheap, I've been using them with USB-SATA adapters, much as I previously used thumb drives. But I do have a thumb drive attached to my keychain, give them to friends and families as a way to distribute photos, and use them for keeping my collection of bootable Linux ISOs and macOS installers.
 


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