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maverick1987 Author

Level 1

34 points

Slow boot time after update to Mojave - External SSD

Hello!

I have a iMac 21" 4k 3,1ghz 2015. I installed an external SSD Samsung 860 Evo 512gb to avoid losing the Apple 1yr warranty if I opened my iMac by myself.

So when I was using APFS format and OSX High Sierra, my iMac used to start, then 2 seconds with a completely empty screen(black) looking for the boot SSD, then the Apple logo appear and it would take another 18 seconds for the system to start completely.

Total boot time = ~20secs.

Now I installed the new MacOS Mojave and my current boot time are very very slow; when I turn on the computer the screen stills black for 2 minutes more or less "looking for my external boot SSD" and then the Apple logo appear and +18secs the system starts.

My current boot time = More than 2~3minutes!!!!

I have also a MacBook Pro 2017 TouchBar and TouchID with 512GB integrated SSD also with APFS format, and update this from High Sierra to Mojave at the same day/time to the iMac. Fortunately the MacBook Pro booting done in about 20secs.

So... There is any solution for fixing this "everlasting" blank screen when booting the iMac with MacOS Mojave and external SSD with APFS format?

I've researched about this, but I can't find anything to solve it. So, I hope someone here may help me!

Thanks!

iMac, macOS Mojave (10.14)

Posted on Sep 28, 2018 8:34 AM

Top-ranking reply

maverick1987 Author

Level 1

34 points

Posted on Oct 3, 2018 11:44 PM

Hello everyone,

i've found the solution.

The reset of the SMC not work, during the night (all the night) I shutdown the mac and disconnect the power, so the power cord is disconnected for about 7-8 hours.

A friend lent me a ssd thunderbolt drive, which I completely formatted.

With UtilityDisk have created a new APFS partition, and I used Carbon Copy Cloner to do a clone of the entire SSD USB3 to the new Thunderbolt SSD.

After the clone finished I've rebooted the mac, set the new drive as Startup Disk under the settings panel.

After the chime, now the apple logo appear after more or less 10 secs.

The boot time is now reduced from 2-3minutes to complessively about 20-30secs from the chime to OSX.

I've used only the Carbon Copy Cloner app, nothing else; nothing command settings, nothing particular settings.

So, in the conclusion, the problem is the USB3 enclosure (can be the TRIM functionality that is not present to the USB3 enclosure, even if it supported the TRIM and the UASP functionality.

Thank you for all, my friends !!

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345 replies

tony_sk8

Level 1

8 points

Jan 25, 2019 6:48 AM in response to Del Rei

UPDATING Mojave 10.14.3:

(Imac 2017 - 3,4 GHz Intel Core i5 - 8 GB 2400 MHz DDR4 - Radeon Pro 560 4096 MB - Fusion Drive 1Tb)

Boot without any external ssd connected (ONLY FUSION DRIVE) = ~ 25sec

Boot with the FUSION DRIVE and connected sdd external (SAMSUNG T5 USB Type C - 1Tb) = ~ 47sec

Boot with SDD external (SAMSUNG T5 USB Type C - 1Tb) = ~ 47sec

There was an improvement with this update .. but there is still a lot to do in my opinion 😟

Jan 25, 2019 7:08 AM in response to tony_sk8

OK, but 3-4 MINUTES between the chime and the Apple logo compared to now 47 seconds for the WHOLE boot process really IS a big improvement if you ask me! You'll always have to accept a certain time sink when booting from an external USB device instead of the built-in Fusion or SSD drive, typically something like 10-15 seconds. If you want to eliminate this too, then you have to retrofit your iMac with a built-in SSD upgrade, I think.

Jan 25, 2019 8:19 AM in response to gerofromronnenberg

It's not booting from an external SSD that I have an issue with. It's the fact that booting is slow if there is an external SSD connected that has been APFS formatted.

There is no booting from external SSD required to hit this bug. Just have an APFS formatted drive attached and you will get the same thing.

polo91

Level 1

13 points

Oct 1, 2018 2:14 AM in response to maverick1987

But interesting thing happens, when i restart and hold Option key (to select startup disk in startup manager mode) and select ssd again, it boots just in 15 secs.