$1300 iMac 4K booting off a USB 3.1 external enclosure?

[Haswell]

I am thinking about getting an $1300 iMac 4K for my parents, but the only thing that I don't like about the iMac is the slow hard drive. I already have a 480GB SSD and I am wondering what type of performance loss and I expect when booting from a USB 3.1 external enclosure.

 

[user1234]

With a good enclosure it's going to be faster than the internal HDD for sure. USB 3.1 supports approximately 625 MB/s theoretical, so depending on the SSD it may be the bottleneck rather than the USB connection.

It will consume some CPU. I don't know how efficient the controller is in the new 4K iMac so I can't estimate any numbers. I would assume that it's not enough to be an issue for everyday use.

A thunderbolt enclosure would be better but also much more expensive.

 

[Fishrrman]

A USB3 (type A connector) external case that specifically supports UASP (USB attached SCSI Protocol) should yield reads around 430mbps and writes between 250-350mbps (write speeds depend on the drive size, mfr, model). This will be roughly 3-4x times faster than booting and running from an internal HDD.

I'm thinking you could put a standard SATA 2.5" SSD into a USB-c/USB3.1 Gen.2 enclosure (which I -think- will support speeds up to 10gbps), and get even faster read/write speeds. But these enclosures cost more.

I predict that both you and your parents will be very pleased with a standard USB3 external booter -- and even more pleased with USB3.1 Gen.2.

Personal experience:
I've been booting and running my late-2012 Mac Mini from an SSD mounted in a USB3/SATA dock for going on FIVE YEARS now. It boots quickly and runs great. No performance degradations at all -- performs as well today as it did on day one.

Again -- just get them accustomed to the concept of "an external boot drive" vis-a-vis the "internal drive", and they'll be fine.

Last word:
DON'T bother with thunderbolt.
USB3 or 3.1 Gen. 2 is "all you need". See my personal experience above once more...

 

[Haswell]

A USB3 (type A connector) external case that specifically supports UASP (USB attached SCSI Protocol) should yield reads around 430mbps and writes between 250-350mbps (write speeds depend on the drive size, mfr, model). This will be roughly 3-4x times faster than booting and running from an internal HDD.

I'm thinking you could put a standard SATA 2.5" SSD into a USB-c/USB3.1 Gen.2 enclosure (which I -think- will support speeds up to 10gbps), and get even faster read/write speeds. But these enclosures cost more.

I predict that both you and your parents will be very pleased with a standard USB3 external booter -- and even more pleased with USB3.1 Gen.2.

Personal experience:
I've been booting and running my late-2012 Mac Mini from an SSD mounted in a USB3/SATA dock for going on FIVE YEARS now. It boots quickly and runs great. No performance degradations at all -- performs as well today as it did on day one.

Again -- just get them accustomed to the concept of "an external boot drive" vis-a-vis the "internal drive", and they'll be fine.

Last word:
DON'T bother with thunderbolt.
USB3 or 3.1 Gen. 2 is "all you need". See my personal experience above once more...

Thanks Fishrrman!!!

Will the iMac recognize the enclosure when being powered by USB or will have I need an AC power adapter?

I am thinking about getting this USB Type-C enclosure.

Oyen Digital MiniPro 2.5" SATA to USB 3.1 (USB-C) External Aluminum Hard Drive

 

[Fishrrman]

RE:
"I am thinking about getting this USB Type-C enclosure.
Oyen Digital MiniPro 2.5" SATA to USB 3.1 (USB-C) External Aluminum Hard Drive"

That should do fine.
I have an Oyen Digital MiniPro (USB 3 version) that I use for backups.
It "mounts right up" with USB bus power only. So I'm going to speculate it will work fine as "an external booter".

Note:
I use the enclosure for a backup drive, and have never actually booted from it (I backup non-booting partitions onto it). But again, it seems to be a solidly-designed enclosure (all metal), one of the best I've seen, and I don't think you'll have any problems...