Is an external SSD really the way to go?

[Lankyman]

As per title is an external SSD the right thing to do on late model iMac's. Please note I'm not thinking about heavy power users but Joe & Jill average. For example I have the 2019 5K 27inch 2TB Fusion Drive iMac which has 128 gigs of fast storage. All my apps will fit comfortably on the fast portion of the FD. Things like iTunes music, iTunes films and photos don't need fast storage and I don't do anything like photo or video editing. Over the weekend I decided to install MacOS on an external SSD using 3.1 USB-C. All went without a hitch.

What shocked me was when I ran Black Magic the external boot drive SSD was only around half as fast as the internal Apple fast storage. If people are concerned about some of their heavier projects hogging the internal fast storage then another option is to put all your data onto the external drive and the apps on the internal which will probably utilise the fast storage.

I realise that for older iMac's an external SSD is still a good option but remain unconvinced that later models benefit from this approach. What do other iMac users think?

 

[CheesePuff]

All depends on the type of external SSD you use, for example Samsung has 3 options:

T5 supports 540 MB/sec read and write
T7 supports 1000 MB/sec read and write
X5 supports ~2400 MB/sec read and write

Obviously cost goes up with speed. If you have an iMac with only a traditional HD or one with a small 24 GB SSD Fusion Drive its a no brainer to get even the T5.

 

[mj_]

Depends on the Mac, the workload, and the amount of data. I don't think external SSDs are a "one size fits all" solution but rather a great solution for most users.

In your specific case it would have probably made more sense to destroy the Fusion Drive core storage device, install macOS as well as your applications on the 128 GB SSD, and keep all your user data such as music libraries or movies on the slower 2 TB hard drive. If, however, you had the 1 TB Fusion Drive this wouldn't work since the SSD portion on that one is only 32 GB, 28 GB of which are usable. In this case an external SSD would be the better solution.

Btw, which external SSD did you get? An NVMe SSD inside a USB 3.2 Gen 1 drive or a dedicated USB 3.2 Gen 1 SSD such as Samsung's T7 should easily get up to 950 MB/s in both read and write. A SATA III SSD will max out at around 500 MB/s.

 

[Lankyman]

All depends on the type of external SSD you use, for example Samsung has 3 options:

T5 supports 540 MB/sec read and write
T7 supports 1000 MB/sec read and write
X5 supports ~2400 MB/sec read and write

Obviously cost goes up with speed. If you have an iMac with only a traditional HD or one with a small 24 GB SSD Fusion Drive its a no brainer to get even the T5.

Hence the caveat late model iMacs with the more generous faster storage.

 

[Lankyman]

Depends on the Mac, the workload, and the amount of data. I don't think external SSDs are a "one size fits all" solution but rather a great solution for most users.

In your specific case it would have probably made more sense to destroy the Fusion Drive core storage device, install macOS as well as your applications on the 128 GB SSD, and keep all your user data such as music libraries or movies on the slower 2 TB hard drive. If, however, you had the 1 TB Fusion Drive this wouldn't work since the SSD portion on that one is only 32 GB, 28 GB of which are usable. In this case an external SSD would be the better solution.

Btw, which external SSD did you get? An NVMe SSD inside a USB 3.2 Gen 1 drive or a dedicated USB 3.2 Gen 1 SSD such as Samsung's T7 should easily get up to 950 MB/s in both read and write. A SATA III SSD will max out at around 500 MB/s.

It was the older Samsung T5. As I already had this I thought it a reasonable test.

 

[ZBoater]

I have my media on external spinning hard drives, as I cannot afford 10TB of external SSD space. So it depends on how much storage you need and what you will use it for. Stuff you use a lot should be on an SSD to ensure maximum performance. But for storage of files you use infrequently or media, a spinning hard drive is still the cost champ.

 

[jobinhosyntax]

I'm hoping so, as I have a 512 SSD iMac on the way. It looks like I'll miss out on faster read write speeds, albeit not by much, might return it for a bigger SSD modal but would have to wait weeks.

 

[mj_]

It was the older Samsung T5. As I already had this I thought it a reasonable test.

Sort of. Keep in mind that SSDs are not primarily fast because they offer high sequential speeds but mainly due to their negligible seek times and very fast random access times. Hard Drives can get up to 500 MB/s in sequential reads as well but fall apart when you start reading random sectors. That's where an SSD truly shines.

I wonder what the percentage of Macs with 2 or 3 TB Fusion Drives versus 1 TB Fusion Drives versus 1 TB hard drives is. The latter two will benefit much more from external SSD storage, even comparatively slow SATA-III speeds, than the first two.

 

[Lankyman]

Sort of. Keep in mind that SSDs are not primarily fast because they offer high sequential speeds but mainly due to their negligible seek times and very fast random access times. Hard Drives can get up to 500 MB/s in sequential reads as well but fall apart when you start reading random sectors. That's where an SSD truly shines.

I wonder what the percentage of Macs with 2 or 3 TB Fusion Drives versus 1 TB Fusion Drives versus 1 TB hard drives is. The latter two will benefit much more from external SSD storage, even comparatively slow SATA-III speeds, than the first two.

That basically is my view to. Being just an average user with the 2TB FD (which includes 128 gigs of fast storage) I doubt I would benefit much if at all by using an external SSD as a boot drive. If however I had the much smaller portion of fast storage as included with the 1TB FD or god forbid an ordinary 1TB HDD then an external SSD is the way to go.

 

[Fishrrman]

"Please note I'm not thinking about heavy power users but Joe & Jill average"

Installing a SATA SSD internally WILL be "a little" faster -- maybe on the order of 20% or so.

BUT -- for the "average" person, going with an EXTERNAL USB3 SSD will be faster, easier, and most importantly, SAFER, because they don't have to pry open the iMac and risk breaking something inside.

THE BEST solution to this "problem" is not to impose the problem upon yourself in the first place.
In other words, if one buys an iMac, one should buy one ONLY with an internal SSD.

They are MUCH faster.

The only exception would be to use a thunderbolt3 external SSD, but these tend to get HOT due to their internal nvme technology. And when they get REALLY hot, they will "throttle back" the drive speeds. This is a particular problem on the Samsung X5...

 

[jobinhosyntax]

The only exception would be to use a thunderbolt3 external SSD, but these tend to get HOT due to their internal nvme technology. And when they get REALLY hot, they will "throttle back" the drive speeds. This is a particular problem on the Samsung X5...

Glyph Atom Pro being the exception

 

[Clix Pix]

I have not had any overheating problems with my Samsung X5's. Yes, they do get warm, and sometimes hot, but not to the point of burning my hand if I were to handle one. The X5 does have a heat sink built into the unit, too.

 

[filmgirl]

I mean, I’ve run full OSes off of T3 and T5 USB SSDs on late-model iMacs (my 2017 iMac for instance) and although the performance isn’t as good as internal, it’s totally serviceable and usable. I just got a T7 and haven’t used it as a boot drive, but it’s significantly faster on my 2020 iMac and even on my 2017 MBP. If you’re doing really performant work off the drive, yeah, TB3 is going to be faster for sure. And Apple historically tends to have faster NVMe drives than other computer makers (though this is changing with PCI 4). But for the average person it’s still good.

I’m not a fan of the Fusion Drive at all. I think it’s a poor solution in a lot of respects — but it really depends on how often you’re accessing the data stored on the HDD part of the drive. If your system and core applications are on the fast storage, you’re going to have a good experience. But if you frequently access a large video or photo or media library, I do still think an external SSD, while less convenient, is going to be faster on a late-model iMac than using the spinning disk drive.

 

[Spk1]

May I suggest this:

OWC Drive Dock | Quick & Easy Bare Drive Access

Swap, boot, and transfer from 2.5 and 3.5-inch drives effortlessly. Includes USB-C/USB-A cables, independent power controls, and cool fanless design.

eshop.macsales.com

I bought this for myself when I bought my new 2020 iMac. It just seemed to have the flexibility and scalability I needed. Plus, coming from a 5,1 Mac Pro, it's just simple to pull out the old drives and plug them into this with the least amount of hassle. Obviously, that won't work for you unless you plan on harvesting your iMac, but it's still reasonably fast and relatively cheap to expand.

 

[petsk]

Basically, if you have more files on your fusion drive than what fits on the SSD portion, an external SSD is going to be faster in almost every way.

Sequential write and read speeds that Black Magic is measuring is not the (only) thing one should stare at. Access times and random read and writes are way more important for a boot drive. Exception would be if you are only using the external SSD as a storage drive for large files, then sequential write and read speeds are more important.

 

[Allied1987]

As per title is an external SSD the right thing to do on late model iMac's. Please note I'm not thinking about heavy power users but Joe & Jill average. For example I have the 2019 5K 27inch 2TB Fusion Drive iMac which has 128 gigs of fast storage. All my apps will fit comfortably on the fast portion of the FD. Things like iTunes music, iTunes films and photos don't need fast storage and I don't do anything like photo or video editing. Over the weekend I decided to install MacOS on an external SSD using 3.1 USB-C. All went without a hitch.

What shocked me was when I ran Black Magic the external boot drive SSD was only around half as fast as the internal Apple fast storage. If people are concerned about some of their heavier projects hogging the internal fast storage then another option is to put all your data onto the external drive and the apps on the internal which will probably utilise the fast storage.

I realise that for older iMac's an external SSD is still a good option but remain unconvinced that later models benefit from this approach. What do other iMac users think?

I agree, but imagin my delima when you got a 21 Mid 2017 Imac that does not have the fusion drive in it but the 5400rpm machanical drive. Soon as it got the Catalina Update and installed oh jesus did the performance go down the drain and took forever to boot. Being it only had the og 8gb of ram too did not help any ether.

Being I knew the ram was able to upgraded and was a standard 2.5 Sata HD in there. I got he parts and had a local Simply Mac store install the parts Total self supplied parts and labor to do so cost me 120(ram)+130(SSD)+150 (installed) set me back 400, but was worth ever penny of it.

If I did not need to upgrade the ram I would have used an usb 3.1 to external SSD and installed the OS and applications and used the internal or file storage. Tho needed to upgrade the ram so maxed it out at 32gb and the SSD makes it feel like a new computer. Just wish the graphics was upgrad able like in the 2011 imac’s, but i will take what i can get!. Even tho externally would have cut the speed of the SSD i half compared to what it was rated anything was faster then that slow ass 5400rpm HDD.

 

[Lankyman]

I agree, but imagin my delima when you got a 21 Mid 2017 Imac that does not have the fusion drive in it but the 5400rpm machanical drive. Soon as it got the Catalina Update and installed oh jesus did the performance go down the drain and took forever to boot. Being it only had the og 8gb of ram too did not help any ether.

Being I knew the ram was able to upgraded and was a standard 2.5 Sata HD in there. I got he parts and had a local Simply Mac store install the parts Total self supplied parts and labor to do so cost me 120(ram)+130(SSD)+150 (installed) set me back 400, but was worth ever penny of it.

If I did not need to upgrade the ram I would have used an usb 3.1 to external SSD and installed the OS and applications and used the internal or file storage. Tho needed to upgrade the ram so maxed it out at 32gb and the SSD makes it feel like a new computer. Just wish the graphics was upgrad able like in the 2011 imac’s, but i will take what i can get!. Even tho externally would have cut the speed of the SSD i half compared to what it was rated anything was faster then that slow ass 5400rpm HDD.

But we’re not talking about the same thing. I started the thread outlining a FD iMac with fast storage. I have said for the iMac with a standard HDD then an external SSD is the way to go. BTW I also have a mid-2011 iMac and upgrading the GPU on that is really not straightforward and even if you get it to run the audio can be really flakey.

 

[prospervic]

I mean, I’ve run full OSes off of T3 and T5 USB SSDs on late-model iMacs (my 2017 iMac for instance) and although the performance isn’t as good as internal, it’s totally serviceable and usable. I just got a T7 and haven’t used it as a boot drive, but it’s significantly faster on my 2020 iMac and even on my 2017 MBP. If you’re doing really performant work off the drive, yeah, TB3 is going to be faster for sure. And Apple historically tends to have faster NVMe drives than other computer makers (though this is changing with PCI 4). But for the average person it’s still good.

I’m not a fan of the Fusion Drive at all. I think it’s a poor solution in a lot of respects — but it really depends on how often you’re accessing the data stored on the HDD part of the drive. If your system and core applications are on the fast storage, you’re going to have a good experience. But if you frequently access a large video or photo or media library, I do still think an external SSD, while less convenient, is going to be faster on a late-model iMac than using the spinning disk drive.

Appreciate your thorough comments. I'm also looking at going the external SSD route, but my 2015 5K iMac does not have Thunderbolt 3, so I'd be stuck with USB 3.0, which is hugely slower (only averaging 425mbps on Black Magic Speed Test).

You provided strong arguments for getting the 2020 iMac 5k on another forum, and I'm slightly tempted by this. But the idea of a new, redesigned iMac with Apple Silicon is highly tantalizing, so I'm hoping my 16" MBP will serve as my "modern" computer while waiting until next year. (Although, truthfully, it's not really an ideal substitute.)