Dual boot from SSD

Question

Dual boot from SSD

Hello all,

I have an iMac 2017 27’‘ that uses that wonderful piece of crap that’s currently called fusion drive.

I would upgrade to an ssd but I’m not insane to open my iMac and ending up with a broken iMac.

The next best thing would be to boot from an external ssd and it seems that the Samsung T5 is the most cost effective drive.

The problem is that I currently use Boot Camp to dual boot MacOS and Windows 10.

Would be possible to do the same thing on external SSD?

I know you can install MacOS on an external drive and I know you can install Windows on an external drive using a workaround, but can you install both and run it as a dual boot the same way I do it today with the internal drive?

What about TRIM support?

Thanks

iMac (Retina 5K, 27-inch, 2017)

Posted on Jun 14, 2018 10:45 AM

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Answer 1

Loner T

Level 9

59,546 points

Jun 14, 2018 11:55 AM in response to Marcelo Henrique Almeida

Are you running into any issues with the Fusion drive?

You can boot macOS from the T5, but not Windows. Windows must stay on the internal disk. The workarounds to install both on the external drive can cause problems later.

TRIM cannot be supported on external disks due to the connection type. A USB-connected SSD is considered external media, not an SSD drive. See the man page of trimforce command.

Here is an example of a T3 connected via USB3 to a Mac.

diskutil info disk2

Device Identifier: disk2

Device Node: /dev/disk2

Whole: Yes

Part of Whole: disk2

Device / Media Name: Portable SSD T3

Volume Name: Not applicable (no file system)

Mounted: Not applicable (no file system)

File System: None

Content (IOContent): GUID_partition_scheme

OS Can Be Installed: No

Media Type: Generic

Protocol: USB

SMART Status: Not Supported

Disk Size: 250.1 GB (250059350016 Bytes) (exactly 488397168 512-Byte-Units)

Device Block Size: 512 Bytes

Read-Only Media: No

Read-Only Volume: Not applicable (no file system)

Device Location: External

Removable Media: Fixed

Virtual: No

OS 9 Drivers: No

Low Level Format: Not supported

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Answer 2

Loner T

Level 9

59,546 points

Jun 17, 2018 9:02 PM in response to Marcelo Henrique Almeida

There is a VMWare/Winclone path to external disk installation - Resolved - Install a Windows 7 partition on Mac OSX without Optical Drive or USB | MacRumors Forums .

There is a WinToUSB path - https://www.easyuefi.com/wintousb/ and Run Windows 10 from an external SSD disk? Yes, it works! .

There is also a method to get Bootcamp on the internal SSD is Re: BootCamp on SDD on system with Fusion Drive but the SSD size is a challenge.

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Answer 3

Loner T

Level 9

59,546 points

Jun 17, 2018 7:00 PM in response to Marcelo Henrique Almeida

From the Amazon link you posted..

OS Compatibility

macOS Sierra and later

Mac compatibility in macOS only; Boot Camp not supported at this time

Windows 10, 8.1, or 7

Uses the multi-platform exFAT file system

(Can be reformatted for use with other file systems)

Can you post the link of the discussion where BC/Windows was installed on this disk?

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Answer 4

Jun 17, 2018 5:53 PM in response to Loner T

Hello again,

I’ve read somewhere here at the forum that if I use a thunderbolt 3 drive instead of USB, I will get trim support and I would be able to install windows to an external drive. Do you know if it’s true, because someone recommended me this drive and the speed seems to be pratically the same as Apple SSD.

Plugable Thunderbolt 3 External 480GB NVMe SSD Hard Drive for Mac and Windows (Up to 2400MB/s+ Read, 1200MB/s+ Write) https://www.amazon.com/dp/B0799SDR6H/ref=cm_sw_r_cp_api_ljWjBbYACN9C2

Thanks again!

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Answer 5

B_Ahmed

Level 1

18 points

Jun 18, 2018 6:45 PM in response to Loner T

Dear Loner T, Please consider solving this issue:

Bootcamp can't boot after resizing "Missing Operating System_".

thanks in advance...

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Answer 6

Jun 14, 2018 6:03 PM in response to Loner T

Hello!

I'm not having any issues with fusion drive, except the fact that's really slow. I'm coming from a PC with a SSD and this is my first mac, so I'm a little frustrated with the speed I'm getting.

Windows boot and usability is really really slow. Much slower than MacOS. It takes more than a minute to boot up because Boot Camp install Windows on the regular hard drive and don't use fusion.

I've tried running parallels but Windows becomes barely usable. I'm not sure if the 8gb of ram are the culprit for this.

My goal here is to make things faster and an SSD would help me a lot, but I don't want to open my brand new mac to install a SSD and a thermal sensor that God knows if it's gonna work properly or if I'm gonna end up with overheating issues and noisy fan.

Thank you very much for the example you've posted. It helped me to give me an idea of how it works before purchasing the drive.

But do you have any ideas on how to make my system faster both on MacOS and Windows?

Thanks!

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Answer 7

Jun 15, 2018 6:10 PM in response to Loner T

Hello again,

I don't have enough space to put windows on the SSD part because the SSD part of my fusion drive is around 28gb.

I think I'm gonna replace the HD with an SSD. If I do that, will I still have a fusion drive with two SSDs? Is that practical or I should remove the fusion 28 gb ssd as well?

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme 28.0 GB disk0

1: EFI EFI 314.6 MB disk0s1

2: Apple_CoreStorage Macintosh HD 27.6 GB disk0s2

3: Apple_Boot Boot OS X 134.2 MB disk0s3

/dev/disk1 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk1

1: EFI EFI 209.7 MB disk1s1

2: Apple_CoreStorage Macintosh HD 498.4 GB disk1s2

3: Apple_Boot Recovery HD 650.0 MB disk1s3

4: Microsoft Basic Data BOOTCAMP 500.5 GB disk1s4

5: Windows Recovery 511.7 MB disk1s5

/dev/disk2 (internal, virtual):

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS Macintosh HD +525.0 GB disk2

Logical Volume on disk0s2, disk1s2

E99E8A91-C53A-4961-BEF6-BE18C0CD932F

Unencrypted Fusion Drive

+-- Logical Volume Group FF3FB4DA-69C7-4460-AFEF-7E5F87F4FCA9

=========================================================

Name: Macintosh HD

Status: Online

Size: 525916364800 B (525.9 GB)

Free Space: 212992 B (213.0 KB)

|

+-< Physical Volume B9CF8715-E633-4F50-BFAB-7967CB3A6024

| ----------------------------------------------------

| Index: 0

| Disk: disk0s2

| Status: Online

| Size: 27551166464 B (27.6 GB)

|

+-< Physical Volume 6B83FC89-ECF1-4342-BE30-B8C28AE33E91

| ----------------------------------------------------

| Index: 1

| Disk: disk1s2

| Status: Online

| Size: 498365198336 B (498.4 GB)

|

+-> Logical Volume Family 230CBA73-EA92-4F4E-BF3A-C2E0DC37B659

----------------------------------------------------------

Encryption Type: None

|

+-> Logical Volume E99E8A91-C53A-4961-BEF6-BE18C0CD932F

---------------------------------------------------

Disk: disk2

Status: Online

Size (Total): 525000507392 B (525.0 GB)

Revertible: No

LV Name: Macintosh HD

Volume Name: Macintosh HD

Content Hint: Apple_HFS

LVG Type: Fusion, Sparse

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Answer 8

Loner T

Level 9

59,546 points

Jun 16, 2018 5:17 AM in response to Marcelo Henrique Almeida

The Fusion model provides a fast (and recently used block) storage and a slow (not used recently) storage. A single drive is easier to manage, but provides less redundancy than a 2-drive system. Both have their advantages. You will need to decide what you want, depending on your usage.

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Answer 9

Jun 18, 2018 6:45 PM in response to Loner T

I didn’t see that! I saw at the forums a guy asking about macos boot and the manufacturer said it was possible so I didn’t paid attention to the description in Amazon.

I don’t have the link for the dual boot on external drive. I’ve read here on the forum a guy saying that was possible to install Windows on an external thunderbolt drive, but there are a lot of people here that don’t know what they’re talking about.

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Answer 10

Jun 15, 2018 10:00 PM in response to Loner T

Are there any speed advantages keeping both drives or just one?

Thank you very much for all your help.

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Answer 11

Jun 18, 2018 6:46 PM in response to Loner T

I’m gonna try those solutions! Thank you very much for all your help. You’ve helped me a lot. Thank you!

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Answer 12

Loner T

Level 9

59,546 points

Jun 19, 2018 3:41 AM in response to Marcelo Henrique Almeida

Please post back if you run into any issues.

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Answer 13

Loner T

Level 9

59,546 points

Jun 14, 2018 6:19 PM in response to Marcelo Henrique Almeida

Marcelo Henrique Almeida wrote:

I'm not having any issues with fusion drive, except the fact that's really slow. I'm coming from a PC with a SSD and this is my first mac, so I'm a little frustrated with the speed I'm getting.

The macOS side with the SSD is not slow, but...

Marcelo Henrique Almeida wrote:

Windows boot and usability is really really slow. Much slower than MacOS. It takes more than a minute to boot up because Boot Camp install Windows on the regular hard drive and don't use fusion.

There is a method to move the Windows to the SSD part, but since it already installed, you will have to use a third-party commercial tool like Winclone and a diskutil cs resizestack command to put Windows on the SSD. The challenge with the SSD is the size.

Marcelo Henrique Almeida wrote:

But do you have any ideas on how to make my system faster both on MacOS and Windows?

Post the output of

diskutil list

diskutil cs list

Here is an example of BC/Windows on SSD. This is on a Mini with a 256G SSD/750G HDD.

diskutil list

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *256.1 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_CoreStorage OSX-FusionHD 128.0 GB disk0s2

3: Apple_Boot Boot OS X 134.2 MB disk0s3

4: Microsoft Basic Data BOOTCAMP 127.2 GB disk0s4

/dev/disk1 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *750.2 GB disk1

1: EFI EFI 209.7 MB disk1s1

2: Apple_CoreStorage OSX-FusionHD 749.3 GB disk1s2

3: Apple_Boot Boot OS X 650.0 MB disk1s3

/dev/disk2 (internal, virtual):

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS Macintosh HD +869.5 GB disk2

Logical Volume on disk0s2, disk1s2

9EAB05A8-8FF3-489E-95C1-8C9BC06EE250

Unencrypted Fusion Drive

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Answer 14

Loner T

Level 9

59,546 points

Jun 15, 2018 6:27 PM in response to Marcelo Henrique Almeida

Marcelo Henrique Almeida wrote:

I don't have enough space to put windows on the SSD part because the SSD part of my fusion drive is around 28gb.

Your SSD has a 4K block size instead of the 512-byte sector size, but it is still tricky to use it.

Marcelo Henrique Almeida wrote:

I think I'm gonna replace the HD with an SSD. If I do that, will I still have a fusion drive with two SSDs? Is that practical or I should remove the fusion 28 gb ssd as well?

I suggest replacing the 1TB HDD with a 1TB SSD, and a Fusion drive can be rebuilt using two SSDs. A Fusion drive is typically a 'faster' and a 'slower' drive, but combinations do work. If you replace drives, be aware that you may void your warranty. The other option is to replace both the drives a single SSD.

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