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slow boot on external SSD with Mojave

I installed Mojave on an external SSD for testing. It formatted the SSD to APFS. It is very slow to boot to the Apple Logo, about 2 minutes. All works fine once booted. Why so slow to boot? Before always booted up in < 30 secs.

Posted on Sep 30, 2018 1:49 PM

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Sep 30, 2018 2:31 PM in response to tbirdvet

2 minute seems to be a bit long, but the boot process always takes a little longer when 2 or more bootable partitions are involved. In this case, it's your internal and your external. If you boot to your internal while the bootable external is connected, it will take longer to boot too. You can also see this if your internal drive was partitioned into 2 separate bootable partitions. I generally use 2 bootable partitions on my internal drives when testing upgrades, but once their released I repartition them back to single partitions and they always boot faster afterwards.


Boot speed is also going to be influenced by the type of connection in use, i.e., Firewire, Thunderbolt, USB2, ESB3 etc., something you didn't provide.

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Sep 30, 2018 4:24 PM in response to Lanny

Lanny, my external is running off a USB3 port (2012 Mini). I believe you may be on to something about two drives connected at the same time. My internal drive is an SDSD HFS formatted and with the external SSD APFS formatted there may be some interaction resulting in slow external boot.

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Oct 28, 2018 5:40 AM in response to tbirdvet

Same issue as described on my 2017 iMac 3GHz. I'm running T5 Samsung SSD drive as my primary bootable/operating system (with bootcamp to my internal mechanical HD). Once I upgraded to Mojave, and rebooted, a blue screen appeared and would not go away (I did not wait as long as four minutes as described above). I've erased my external drive and reinstalled Mojave per Apple support and nothing changed. The only way I can boot now is by pressing "option" on startup and manually selecting the external drive (even though it is already pointed to this drive in system preferences>startup disk.


Thoughts??

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Nov 4, 2018 10:14 PM in response to lindy4

I made some tests, but nothing seems to work.


I connected a second external SSD USB3 and created two HFS+ partitions.


I installed a fresh Mojave 10.14.1 on one partition that was automatically converted to APFS.


Booting from this partition had the same behavior (~2 3 minutes).


As someone suggested that the problem comes from the APFS, I used SuperDuper to copy the Mojave APFS partition to the HFS+ new one.


Once finished I got Mojave installed on HFS+.


I changed the starting boot in the preference pane, shut down and restarted.


Unfortunately, the iMac boot is still very slow on Mojave HFS+.

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slow boot on external SSD with Mojave

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