Booting off external SSD speed difference. Existing fusion signs of issues.

[400]

Late 2013 with a 1tb fusion. Showing some errors and want to pre empt a possible fail.
I already have Mac OS on external spinning hard drives as a "just in case" but runs slows (obviously). Pretty good back up in place.

The Fusion mainly has apps (inc Steam, other games), OS and docs. Photos library is on an external spinning hard drive (700gb or so).

All I want to do is make the first possibly second iteration of the new iMacs so if I run a SSD as boot and day to day running via the USB, will it function as per it is now with the fusion and still run at a similar rate? Is there any point thinking of using the thunderbolt port?

I would rather get this going before finding out when it fails.

 

[Juicy Box]

What OS are you using?

All I want to do is make the first possibly second iteration of the new iMacs so if I run a SSD as boot and day to day running via the USB, will it function as per it is now with the fusion and still run at a similar rate?

Maybe it is because I am going to sleep soon, and pretty tired, but I read this multiple times and I cannot understand what you are asking.


Are you saying that you are trying to use some type of external storage solution for your Late 2013 iMac to keep your iMac going until the M1 iMacs are out sometimes in the next few years?

And, your only concern is whether or an external storage solution would be as fast as your existing Fusion Drive?


I have ran all sorts of external drive as boot drives. FW400, FW800, USB2, USB3, TB1/2, TB3, thumb drives, SD cards, PATA, SATA, NVMe, External HW Striping RAIDs, External SW Striping RAIDs, etc..... I have even ran MacOS on old iPods.

There is nothing wrong with running MacOS on an external drive, and cannot ever remember having an issue with it.

Getting a SATA SSD and a USB Enclosure or USB3/SATA adapter cable is really affordable now. A 1TB SSD and enclosure could be purchased for less than $90 if you are in the US.

Speed wise, you would probably see similar speeds to your Fusion Drive. USB3 will give you about 400MBps speeds. Your Fusion Drive when it was brand new would most likely beat this speed unless you were doing long writes or if you were accessing data that was stored in the HDD.

The SSD portion of a seven year old Fusion Drive would probably be slower than what you can get with a USB3 SSD.

and still run at a similar rate?

I have booted my Late 2012 iMac from USB, TB1, and TB3 drives (connected to the TB1 port). My iMac is currently booting from a Samsung X5 NVMe TB3 drive via the TB1 port, and gets speeds almost 900MBps.

There was no real difference in speed when booting from SATA USB and SATA TB1 drive. I get about 350-400MBps with both.

I didn't try it, but someone on the forum with a Late 2012 iMac booted from a TB2 NVMe drive, and got speeds about 700Mbps via TB1.

Is there any point thinking of using the thunderbolt port?

The biggest downside to using USB over Thunderbolt is the lack of TRIM support for MacOS with USB drives.

TB drives have TRIM support.



I personally suggest just going with a SATA USB3 enclosure or adapter and a SATA SSD.

This will give you decent speeds compared to your aging Fusion Drive, but will not cost that much. You will not have TRIM support, but if you plan on getting a new iMac in the next few years, this won't really matter much in the long run.

You could see a decent speed increase and TRIM support if you go with a NVMe SSD over TB2 or TB3, but this would cost 3x as much per GB as using the USB3 solution (400MBps).


You could spend more than twice as much and get a TB2 NVM SSD (700MBps) as a happy medium between speed, TRIM support, and cost.

If speed was your goal, you could go with a TB3 NVMe (900MBps), but you would also have to get a TB3 dock to power the external TB3 drive, an Apple TB2/TB3 bidirectional adapter, and a TB2 cable. So, probably a bigger investment you were planning on making. The silver lining is that you could continue to make use of the investment on your next iMac, but run the NVMe at full speed (3000MBps).

 

[mwidjaya]

I would rather get this going before finding out when it fails.

If I plan to keep the 2013 iMac for a while, I would be looking into replacing the internal HDD with SSD.

See guide from ifixit

iMac Intel 27" EMC 2639 Hard Drive Replacement

Replacing the hard drive requires separating the display and removing the left speaker. This guide also includes steps to upgrade your iMac's hard...

www.ifixit.com

Depends of how handy you are. I would have no issues getting a kit and DIY.

While at it, I would probably also upgrade the original blade SSD. They can fail too and it is best to do it all in one shot while the iMac is opened up.

 

[400]

Maybe it is because I am going to sleep soon, and pretty tired, but I read this multiple times and I cannot understand what you are asking.

OS is Catalina.
Basically keep this iMac going and wait and see with the new chip iMacs (M1?). As long as it is on par give or take existing fusion.

My spinning externals are a tad clunky running OS. But they work, but hoping SSD will improve on them.

From your reply sounds like chuck a USB3 SSD as per your description at it to make it every day use for a year or so tops. I can live with that if it is acceptable.
But the TB option might investigate out of interest.

If I plan to keep the 2013 iMac for a while, I would be looking into replacing the internal HDD with SSD.

Don't mind taking it apart but only when it is a second machine but thanks for the pointer, I had already considered that and it will happen probably when the new iMac is bought whenever that is.

Thanks for the replies. I think I am sorted now.

 

[Fishrrman]

Don't take the iMac apart.

Just get an external USB3 SSD or put one together yourself (with a bare 2.5" SATA SSD and an enclosure).

You probably don't need larger than 500gb, or perhaps you could even get by with 250gb.

Put on it:
- The OS
- Applications
- Basic accounts (you already keep your large libraries on an external drive, let them stay where they are for now).

With USB3, you should see read speeds in the 420-430MBps range.
This setup ought to hold you over until the new iMacs come out later this year.

 

[400]

Don't take the iMac apart.

Yeah, keeping that for when I have a new one. Main machine at the moment so would not risk it with an easy plug in option.

Disappeared down the NVMe SSD rabbit hole for a look see. Didn't even know about it. Interesting stuff.
But, as mentioned further up. USB3 SSD.

Edit 7/1/21. Don't need to bump this but samsung 1tb slotted into an external case, USB 3 running quite well. Initially installed OS on external then used Apple Migrate to shift over the files and settings and it run very buggy crashy pain in the neck. reset NVRAM and it seems to have all clicked together nice and settings for programs clicked in after this reset. NVMe SSD was tempting but most cases not the right connector, don't like adapters if I can avoid it.

Affinity Photo, use that a lot, that fires up a heck of a lot quicker and runs sweet as a nut.

Thanks again all.

 

[fpb]

Yeah, keeping that for when I have a new one. Main machine at the moment so would not risk it with an easy plug in option.

Hi - just wondering how you went with booting from the external USB3 SSD drive on your iMac?

I'm in the exact same situation as you - the spinning disk portion of my fusion drive is dying ( I have a 2014 iMac with TB2).

So far I've managed to split my fusion drive and boot solely from the SSD portion which actually works really well.

I'm after an external SSD for more storage and wondering if you found the external USB3 type A SSD speed comparable or faster than the fusion drive.

 

[mdgm]

The fastest external option would be:

iMac -> TB(1/2) cable -> Apple TB3 to TB2 adapter -> TB3 dock -> TB3 NVMe drive. If you get an AC powered (i.e. not bus powered) drive then you don't need the dock.

USB3 is a lot cheaper obviously, but if you plan to reuse the NVMe drive and/or dock with a newer Mac down the line then it's still an option worth considering. If you go down the TB3 NVMe drive route, be sure to check the minimum OS requirements for the dock and the NVMe drive. You'd likely need to run at least High Sierra.

The only situation in which a fusion drive would be quicker than USB3 is if a task only requires reading/writing to the SSD portion of the fusion drive. Booting just off the internal SSD drive provided you have plenty of free space should be faster than booting off a USB3 drive. USB3 is a little slower than an internal 2.5" SATA III SSD.

Personally I'm booting a 2011 iMac off a TB3 NVMe drive, but it's an easier choice on that Mac as it has TB1, USB2 and FW800, but no USB3.