Add SD card to Fusion Drive in MacBook Pro 12,1 I want to know if it's possible to add a 128 GB SD card to my MacBook Pro 12,1 (13-inch Retina, early 2015) and make 250 GB Fusion drive.

$ sudo diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *121.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            120.5 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           +120.5 GB   disk1
                                 Logical Volume on disk0s2
                                 D3021BC9-8BCA-40BA-9B7C-07F28BDE678B
                                 Unencrypted
/dev/disk2 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *129.8 GB   disk1
   1:                  Apple_HFS Transcend               129.8 GB   disk2s1




$ sudo diskutil cs list

CoreStorage logical volume groups (1 found)

Logical Volume Group 878F63CA-69DB-43F2-8708-271D776049F5

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

    Name:         Macintosh HD
    Status:       Online
    Size:         120473067520 B (120.5 GB)
    Free Space:   0 B (0 B)
    |
    +-&lt; Physical Volume 0303DA39-F711-42D5-AB0B-7C35015763B3
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk0s2
    |   Status:   Online
    |   Size:     120473067520 B (120.5 GB)
    |
    +-&gt; Logical Volume Family EA26D69A-ED32-4088-BBF5-DD4ED4A01FE2
        ----------------------------------------------------------
        Encryption Type:         AES-XTS
        Encryption Status:       Unlocked
        Conversion Status:       Complete
        Reversion State:         Reverting
        High Level Queries:      Not Fully Secure
        |                        Has Visible Users
        |                        Has Volume Key
        |
        +-&gt; Logical Volume D3021BC9-8BCA-40BA-9B7C-07F28BDE678B
            ---------------------------------------------------
            Disk:                  disk1
            Status:                Online
            Size (Total):          120473067520 B (120.5 GB)
            Conversion Progress:   Complete
            Revertible:            No
            Revert Status:         PV to LV passthrough mode
            LV Name:               Macintosh HD
            Volume Name:           Macintosh HD
            Content Hint:          Apple_HFS


Following an iBook from Carlos Burgues &amp; Pablo Romeu called "Fusion Drive, Crea tu propia unidad Fusion drive en tu Mac" I think the commands would be:

sudo diskutil cs addDisk 878F63CA-69DB-43F2-8708-271D776049F5 disk2s1
diskutil cs resizevolume D3021BC9-8BCA-40BA-9B7C-07F28BDE678B 249,8g


But I'm not sure how to make it work properly and I have some questions about the process:


Can I make changes directly on disk, or I must boot from another source to add the 128 GB SD card?
Is it better to restore a carbon copy (or Time Machine) to a new &amp; formatted 250gb Fusion drive?
Will I loose the Recovery HD?
Is there a better way to do this? (something like tardisk Pear software)


I really appreciate you to try to help me, but please, really, don't answer with something like: Don't do it (SD cards are no reliable, bad speeds, etc), or buy a better laptop, or something similar. The HDD can't be upgraded, so I want to try this solution.
You need to create a RAID 0 Striped Array. Here is how to do it: https://www.lifewire.com/use-disk-utility-to-create-a-raid-0-striped-array-2260918