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We all know we can create bootable USB with Rufus and live ISO like LiveGNOME ISO file, but in my experience it can't save settings and data which means it'll reset to default value every time you reboot it.

So I'm thinking: is it possible to act USB as an computer hard drive if it got enough I/O speed and storage? If yes, then is it possible in install CentOS in the USB using DVD/everything ISO by selecting USB as the drive in the installation process? Also, will it modify the things on other drive in the installation process to the USB drive? Last, can we boot the CentOS on other computer using the USB stick with the settings we've set on previous computer?


I know it might looks like I have a few questions in this question but basically I just want to know if can we install CentOS on USB like the normal way we install on computer with DVD/everything ISO file?

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Yes you can install centos in USB drive. Don't install it in the same USB disk which you're using as installer. Use separate usb disk as installer and installation. Or you can keep the installer in a CD disk.

Select boot drive properly while using the CentOS installed in the usb. You may install bootloader into the usb drive to make it bootable and select it as first boot drive. Otherwise skip bootloader installation in the usb drive and make a proper enty in grub configuration of your existing Linux system in hard drive

Installation procedure is same as installing in hard deive. It's better to install in a USB 3 drive for better performance.

  • Then should I just drop the iso into the USB for installer or I still need to use Rufus to extract it? – Andrew.Wolphoe Dec 29 '17 at 18:21
  • Both simple dropping the iso or extracting it into usb drive will not work. Use dd to burn the iso into usb. Like dd if=path-to-iso of=/dev/sdX (replace X with usb drive's letter). It'll take quite long to burn the image. So please keep patience. – Abhik Bose Dec 29 '17 at 18:29
  • So it can't work if I download CentOS iso on Windows and use Rufus to put it into USB? (Cause I don't really knows what Rufus do) – Andrew.Wolphoe Dec 29 '17 at 18:30
  • I also never used rufus. If it's a dd like tool it'll work. Try once. There are several dd like tools available for windows. Unnetbootin is one. But they often fail. So only way out is trial and error with available tools in for windows. I can only assure that dd in Linux will definitely work – Abhik Bose Dec 29 '17 at 20:41
  • Sorry, this might look stupid, but I want to know is it possible to know how big will it need before using dd to burn it, or I'll must burn it once to know how much storage the installer will need? – Andrew.Wolphoe Dec 31 '17 at 4:58
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Yeah. That is how you create a portable Linux. You can't have the source and destination as the same USB.

One way to do that without buying an additional USB is to mount the installation ISO to a Virtual Box and then boot into that by making sure your real USB is also connected to it. Select the USB position as the destination for Linux installation.

Some times you might see a UIUD not find issue when you try to boot the real USB. In that case enter the fallback mode in and fix the errors by googling around.

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Yes it is. Plug in the usb drive you want to install the os on. Make an ext partion on it with gparted. Run command sudo blkid and note down it's UUID. Burn the live iso to another usb drive. Boot from it. Plug in the installation target usb. Note it's device name. (Something like sdxn, x is a letter, n is a number). And choose that partition as the installation target. Note that partitioning the usb might not be necessary as installation program might do it for you.

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If you install CentOS 7.6 using LVM scheme on one machine, then transfer your USB drive onto another machine and run yum update there, you may encounter the bug I just had (2018-12-07):

the newly installed kernel (or more like newly built initrd) won't let you boot!

I just found that initrd excluded dm (Device Mapper) and lvm from Dracut modules for some reason.

I had to bring USB drive back to the original machine (laptop) and run there:

$ sudo yum reinstall 3.10.0-957.1.3.el7.x86_64

After this my USB drive containing CentOS 7.6 started booting the new kernel on both machines.

Probably a bug, I am not sure. Just noting.

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