Sandisk Extreme Portable SSD 1TB (55AF) Refuses to boot anything in UEFI mode.


I was hoping to boot Linux (or any OS) from this external SSD. However, no matter what I try, I cannot convince it to boot. It simply does not show up in the boot sequence menu (BIOS) where USB is set first.

Even when I physically remove all other drives from my Toshiba laptop and install Linux while letting it install by overwriting the complete drive by the install routine. That worked fine on a Seagate USB HDD. Even when I clone that HDD to the SSD, no joy.

Just for testing: When I flash the variety of Linux live ISO’s to a simple regular USB thumb drive, they will boot without any issues. When I flash each very same ISO image to the Sandisk Extreme Pro 1TB portable SSD, it will not show up in the boot sequence menu.

I used Rufus which selects DD as duplicating method for Garuda. For Linux Mint Rufus will let you choose between flashing the ISO image or use DD for Disk Dupe of the ISO image. I tried both methods with the same disappointing result. I also tried Balena Etcher with same results.

When I manually create a GPT partition table and a 300 MiB FAT32 EFI partition, followed by the Root partition and as lastly the Swap, mount point “/boot/efi/” and the “boot”, and “root” -flag etc… Then installing Linux (replacing partition method). Same result, Nada…

My 2012 Toshiba Satellite Laptop is set to UEFI in the BIOS. Secure Boot and Fast Boot are definitely turned off. All my other boot-drives (internal and external) are GPT & UEFI and work fine and boot as intended. External drive is connected by USB3 (might be 3.1 not sure right now). I have tried different USB ports.

Even tried another laptop (2016 HP with UEFI, Secure boot Off, Fast boot Off), no joy while other drives boot just fine with the very same OS installed.

This Sandisk Extreme Pro 1TB (55AF) keeps refusing, no matter what What’s soo different about it?

I’ve tried with the latest images of Garuda Dr460nized, Garuda Dr460nized Gamer Edition, Garuda KDE, Linux Mint, Arch (Calamares installer), PoPOS and even Ubuntu.

For every edition I tested if it would boot after flashing the live ISO to the Sandisk. None did.

For every edition I installed on another HDD, and then on the Sandisk… The installation always works fine without any errors. The Sandisk just won’t boot while every other drive I could get my hands on just works fine. The only way I can have the Sandisk show up in the Boot order menu (BIOS) is when I change UEFI to CSM+AHCI (did not try Legacy), but then the OS will not boot as those are set up for UEFI with a GPT Partition Table and not with a MBR.

Now, I had a good solid plan using this USB SSD as an external boot drive for Linux (or any OS). Sadly the drive is just demoted as a too expensive backup file storage of which I have no lack of.

It just sounds soo wrong having to turn everything back to the Middle Ages having to re-setup the internal drives as legacy AHCI with a MBR, just because that pesky Sandisk Extreme Pro portable SSD is acting up and refusing to do what others do without a even a sweat. No, I’m not even gonna try MBR. That’s just ridiculous.

Anyone any ideas? What am I missing? What else can I try to convince it to boot?


In addition to my former post, I just manually installed Arch on the Sandisk Extreme Portable Pro SSD (55AF) by following Jay’s guidelines:

GPT Partition Table, a 500 MB FAT32 EFI partition, a second partition filling the rest of the space for Linux Arch.

The install itself (UEFI and No encryption) went smooth without any issues up until the reboot. The Sandisk Extreme Portable Pro SSD does not show up in the boot order menu of the laptop. Since I had taken out the internal (SATA) SSD and (SATA) HDD, the laptop ended up complaining that there was no Boot Device.

Other USB HDD and Flashdrives work fine and boot without a sweat. Also tested on a modern laptop with the same disappointing result: Zilch, Nada.

What’s so special about the Sandisk Extreme Portable Pro SSD that it keeps refusing to boot? I’m running out of ideas. Anyone?

Hi @Traveller_NL,

Please contact the SD Technical Support team for the best assistance and troubleshooting: