Trying to install full ubuntu to a flash drive on my surface book

[sisama]

I am trying to install a full ubuntu to a 32G flash drive and I have a surface book. When I try to select the location to install ubuntu, instead of showing dev/sda, dev/sdc, dev/sdb, it shows
dev/nvme0n1p1 efi
dev/nvme0n1p2
and so on...

I am wondering which location should I choose? Is there anything wrong with it?

Thank you very much

[oldfred]

Your NVMe drive is the internal SSD on your system.

Are you wanting to install from a small flash drive installer to a larger flash drive? Or are you installing to the NVMe drive?

[sisama]

I want to install it to a flash drive instead of my ssd. Can I stall it to the same usb I used to boot ubuntu?
Thank you for your reply.

[sudodus]

Yes, if you use a RAM drive (and unmount the USB pendrive). Is can be done manually with the boot option toram according to the following links.

Boot options (http://ubuntuforums.org/showthread.php?t=2230389&p=13370808#post13370808)

How to unmount a live DVD/USB? (https://askubuntu.com/questions/854527/how-to-unmount-a-live-dvd-usb)

Can Ubuntu be installed to the pendrive it was booted from? (https://askubuntu.com/questions/855039/can-ubuntu-be-installed-to-the-pendrive-it-was-booted-from)

[oldfred]

Probably best to keep flash drive installer.
If install to flash drive does not boot, then you have no way to fix it as you need flash drive in live mode to run repairs.

Also will you be installing in UEFI or BIOS boot mode? If UEFI be sure to partition in advance, use gpt and include the ESP- efi system partition which is formatted FAT32 with boot flag.

Full UEFI install to any external drive is not normally configured correctly by grub. There are two issues, both best if fixed while booted in installer and before rebooting.
Grub only installs to ESP - efi system partition on drive seen as sda. Not sure if your NVMe drives further confuse it as some have worked and others have had issues.
UEFI only boots from /EFI/Boot/bootx64.efi, but grub does not create that file.

Best to just copy /EFI/ubuntu from internal drive to flash drive. Then copy again from internal drive to /EFI/Boot and rename shimx64.efi to bootx64.efi. You have to have both folders as full install grub expects more files in /EFI/ubuntu.

My 32GB flash drive with half for Ubuntu and half for data.

Disk /dev/sdc: 31.0GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number Start End Size File system Name Flags
1 20.5kB 500MB 500MB fat32 esp_usb boot, esp
2 500MB 501MB 1049kB bios_grub
3 501MB 15.2GB 14.7GB ext4 sys
4 15.2GB 31.0GB 15.8GB ext4 data32 msftdata

I often suggest 300 to 300MB for ESP, and used 500MB above. But with flash drive I will not be experimenting a lot and 100MB is probably more appropriate.