Cannot unmount disk to create disk image

Support and Help
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1

Ubuntu Version

Ubuntu 26.04 LTS

Desktop Environment (if applicable)

GNOME

Problem Description

When I open the ‘Disks’ app preinstalled in this OS and click …>create disk image, I get the following text (not an error message per se): “Authentication required. Authentication is required to unmount SanDisk SD7SB3Q-256G-1006(/dev/sda1) mounted by another user”, prompting me to enter my password for my user (which was the first user). After authenticating, I get an error message.

I’m itching to create an ISO file of my disk so I have backups for my projects.

Relevant System Information

Here is the analysis that Inxi provided tonight.

System:
Kernel: 7.0.0-31-generic arch: x86_64 bits: 64 compiler: gcc v: 15.2.0
clocksource: tsc
Desktop: GNOME v: 50.1 tk: GTK v: 3.24.52 wm: gnome-shell
tools: gsd-screensaver-proxy dm: GDM3 v: 50.1 Distro: Ubuntu 26.04.1 LTS
(Resolute Raccoon)
Machine:
Type: Laptop System: LENOVO product: 20L5004HUS v: ThinkPad T480
serial: Chassis: type: 10 serial:
Mobo: LENOVO model: 20L5004HUS v: SDK0J40697 WIN
serial:
part-nu: LENOVO_MT_20L5_BU_Think_FM_ThinkPad T480
uuid: Firmware: UEFI vendor: LENOVO
v: N24ET81W (1.56 ) date: 09/06/2025
Battery:
ID-1: BAT0 charge: 14.7 Wh (79.5%) condition: 18.5/24 Wh (77.1%)
volts: 12.15 min: 11.46 model: SMP 01AV421 type: Li-poly serial:
charging: status: not charging control: start: 75% end: 80% cycles: 86
ID-2: BAT1 charge: 15.7 Wh (77.2%) condition: 20.4/24.1 Wh (84.7%)
volts: 12.13 min: 11.4 model: Celxpert 01AV424 type: Li-poly
serial: charging: status: not charging control: start: 75%
end: 80% cycles: 105
CPU:
Info: quad core model: Intel Core i5-8250U bits: 64 type: MT MCP
smt: enabled arch: Coffee Lake rev: A cache: L1: 256 KiB L2: 1024 KiB
L3: 6 MiB
Speed (MHz): avg: 800 min/max: 400/3400 cores: 1: 800 2: 800 3: 800 4: 800
5: 800 6: 800 7: 800 8: 800 bogomips: 28800
Flags-basic: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
Graphics:
Device-1: Intel Kaby Lake-R GT2 [UHD Graphics 620]
vendor: Lenovo ThinkPad T480 driver: i915 v: kernel arch: Gen-9.5 ports:
active: eDP-1 empty: DP-1, DP-2, HDMI-A-1, HDMI-A-2 bus-ID: 00:02.0
chip-ID: 8086:5917 class-ID: 0300
Device-2: Chicony Integrated Camera (1280x720@30) driver: uvcvideo
type: USB rev: 2.0 speed: 480 Mb/s lanes: 1 bus-ID: 1-8:4 chip-ID: 04f2:b604
class-ID: 0e02 serial:
Display: wayland server: Xwayland v: 24.1.10 compositor: gnome-shell
driver: gpu: i915 display-ID: 0
Monitor-1: eDP-1 model: BOE Display 0x06b3 res: 1366x768 dpi: 112
size: 309x173mm (12.17x6.81") diag: 354mm (13.9") modes: 1366x768
API: EGL v: 1.5 hw: drv: intel iris platforms: device: 0 drv: iris
device: 1 drv: swrast gbm: drv: iris surfaceless: drv: iris wayland:
drv: iris x11: drv: iris
API: OpenGL v: 4.6 compat-v: 4.5 vendor: intel mesa v: 26.0.8-1ubuntu0.3
glx-v: 1.4 direct-render: yes renderer: Mesa Intel UHD Graphics 620 (KBL
GT2) device-ID: 8086:5917 display-ID: :0.0
Info: Tools: api: eglinfo,glxinfo x11: xdriinfo, xdpyinfo, xprop, xrandr
Audio:
Device-1: Intel Sunrise Point-LP HD Audio vendor: Lenovo ThinkPad T480
driver: snd_hda_intel v: kernel bus-ID: 00:1f.3 chip-ID: 8086:9d71
class-ID: 0403
API: ALSA v: k7.0.0-31-generic status: kernel-api
Server-1: PipeWire v: 1.6.2 status: active with: 1: pipewire-pulse
status: active 2: wireplumber status: active 3: pipewire-alsa type: plugin
Network:
Device-1: Intel Ethernet I219-V vendor: Lenovo ThinkPad T480 driver: e1000e
v: kernel port: N/A bus-ID: 00:1f.6 chip-ID: 8086:15d8 class-ID: 0200
IF: enp0s31f6 state: down mac:
Device-2: Intel Wireless 8265 / 8275 driver: iwlwifi v: kernel pcie:
speed: 2.5 GT/s lanes: 1 bus-ID: 03:00.0 chip-ID: 8086:24fd class-ID: 0280
IF: wlp3s0 state: up mac:
Bluetooth:
Device-1: Intel Bluetooth wireless interface driver: btusb v: 0.8 type: USB
rev: 2.0 speed: 12 Mb/s lanes: 1 bus-ID: 1-7:3 chip-ID: 8087:0a2b
class-ID: e001
Report: hciconfig ID: hci0 rfk-id: 0 state: up address: bt-v: 4.2
lmp-v: 8 sub-v: 100 hci-v: 8 rev: 100 class-ID: 6c010c
Drives:
Local Storage: total: 238.47 GiB used: 42.43 GiB (17.8%)
ID-1: /dev/sda vendor: SanDisk model: SD7SB3Q-256G-1006 size: 238.47 GiB
speed: 6.0 Gb/s tech: SSD serial: fw-rev: 0006 scheme: GPT
Partition:
ID-1: / size: 232.64 GiB used: 42.43 GiB (18.2%) fs: ext4 dev: /dev/sda2
Swap:
ID-1: swap-1 type: file size: 4 GiB used: 0 KiB (0.0%) priority: -1
file: /swap.img
Sensors:
System Temperatures: cpu: 45.0 C mobo: N/A
Fan Speeds (rpm): N/A
Info:
Memory: total: 12 GiB note: est. available: 10.94 GiB used: 2.96 GiB (27.1%)
Processes: 302 Power: uptime: 3h 54m states: freeze,mem,disk suspend: deep
wakeups: 0 hibernate: platform Init: systemd v: 259 default: graphical
Packages: 1825 pm: dpkg pkgs: 1791 pm: snap pkgs: 34 Compilers:
gcc: 15.2.0 Shell: Bash v: 5.3.9 running-in: ptyxis-agent inxi: 3.3.40

Error Messages / Logs

I could not copy-paste them, so I handwrote the error messages on paper and typed them onto my computer manually. They are not case-sensitive, but I otherwise captured them verbatim.

“Authentification Required”
“Authentification is required to unmount SanDisk SD7SB3Q-256G-1006(/dev/sda1) mounted by another user”

I enter my password.

“Error unmounting filesystem”
“Error unmounting /dev/sda2: target is busy (udisks-error-quark, 14)”

What I’ve Tried

I’ve preemptively used the task manager within Ubuntu’s ‘Resources’ app to close running programs. I have attempted this several times.

Honestly, I’m confused as to what I can safely do. I must confess that ever since I attempted to install the official monero wallet GUI via terminal (which failed), whenever I open the terminal the default user is now “monero”. I have to switch using the “$ su - user” command, to give you a showcase of my low skill level. It’s annoying.

2

Welcome to Ubuntu Discourse :slight_smile:

Please open a separate topic for the terminal issue with the app you tried installing.

Confusing for users here trying to resolve two unrelated things in the same topic.

Thanks

2 Likes
3

Please, show this error message.

1 Like
4

Haha, you are basically trying to cut off your own legs while standing on them! :smiley:

/dev/sda2 is your root system /. Ubuntu cannot unmount the drive that is currently keeping the entire OS alive - that is why it tells you “target is busy”.

Just boot your laptop from an Ubuntu Live USB- select “Try Ubuntu”, and create the image from there while your main SSD is not running.

4 Likes
5

Please note that Disks (gnome-disk-utility) does not compress the image.

If you need to compress the image, have a look at Clonezilla

1 Like
6

I was about to suggest booting from Live to do that, but Viktor (@steelf ) beat me to it!

:slight_smile:

2 Likes
7

@ericmarceau Not all is lost! For 5 bucks I can delete my comment and you can post it :laughing:

3 Likes
8

I appreciate the responses, everyone. I will update the thread after booting from my live ubuntu usb later today. Whether I succeed in resolving my issue I want to thank you lot for providing input.

@avb66 Okay.

Summary
Summary

@rubi1200 I’m glad to learn more about how people other than me interpret my words. Next time, I will provide a less ambiguous example of my skill (in this area, lack thereof lol) by using generalities.

I will be sure to open a separate thread if I can’t resolve the terminal issue on my own.

@tea-for-one Hey, I would have completely overlooked this if you hadn’t said something. I can’t predict the future, but I reckon you just spared my future self hours of frustration!

9

Not to pick nits, but unless something is really strange about your system, an image of your disk is not an ISO, since that name refers to the filesystem used on cdrom …

Also the use of file system images for backup purposes is not considered a good practice since imaging is comparatively slow and you’re saving the exact same data again and again and … Also pulling a single file or a low number of files out of an image – by far the most common use of backups, usually after deleting more than I wanted to – is possible but quite cumbersome.

There are many backup solutions on Linux which offer things like generational backups that allow you to keep multiple version of a file so you can have the complete version history in your backups and that only store the last changes so that after the initial big backup you’re only storing a small amount of data which will take just a few minutes.

1 Like
10

@hdd-gehrke Thank you for the correction! I assure you that I care about the distinction. Eventually I have to “pay it forward” (to speak figuratively) by answering questions on this forum and it wouldn’t do some people any good to give them misinformation.

That program type you mention reminds me of Git. A while ago I installed Git for project version control, but got overwhelmed and paused. If I’m understanding you correctly, Git’s style of backup is very important and I should either resume learning Git immediately or start learning a similar program. I defer to you on this matter.

Related question, kind commenter: If disk images are bad practice for backups then what is good practice for preserving the following simultaneously so I may rebuild my projects’ organizational structure exactly how it was in the event my laptop dies? 1.) operating system plus its version, 2.) system settings, 3.) folder hierarchy of all of the folders (this is the tricky one), and 4.) names of all downloaded software?

In my next post within this thread, I am going to outline what I spent the past four-ish hours doing. Even though I now know a disk image isn’t a good solution for my problem, I’d like to make this thread more useful for any future lurkers before I mark the thread as “solved”. Stay tuned.

11

Here’s how I unsuccessfully attempted to resolve the issue. Ft. a lot of web browsing (LONG)

I took the advice user @steelf gave me and went looking for my live Ubuntu usb drive. I couldn’t find it, so I created another live usb using this guide (LINK):

Summary

Create a bootable USB stick - Ubuntu Desktop documentation

I archived the guide’s webpage using the Wayback Machine, so the content should still be viewable even when the link rots or the page gets deleted (LINK):

Summary

https://web.archive.org/web/20260910014641/https://ubuntu.com/desktop/docs/en/latest/how-to/create-a-bootable-usb-stick/

I messed up. I don’t remember what mistake I made, but the laptop automatically brought me to the “Try Ubuntu” environment instead of prompting me what to do. I’m not surprised I messed up, this was only my second time creating a live usb; the first time, I used a different guide for installation.
Future lurkers, I recommend opening up the guide on a different device and looking at it as you go instead of trying to recall the instructions from memory—I don’t think the Ubuntu install process wipes preexisting data, I think it just sections it off, but that’s terrible for time-sensitive issue fixes and to me it seems dangerous to assume that OS installations won’t delete everything. (Please correct me if I’m wrong about the latter, everyone.)

I connected to the internet, looked up “Clonezilla”, and read the Clonezilla website’s instructions. I couldn’t understand them. I left the website and skimmed two third-party installation guides to no avail. I skimmed one more before giving up and telling myself I’ll try again later today.

Here’s what I did next. I decided to try the “Disks” program next because hey, what if it works on my device in spite of what that one commenter said? I clicked on the entry for the main disk, selected “create disk image”, and the commenter was right. A disk image could not be made: I was told by the system that there wasn’t enough space on the 64GB usb drive I used for making the live Ubuntu usb, yet 64GB is the biggest filesize of USB drive I own. Then I remembered I have several external hard drives—all of which have a stated minimum of 200GB of available storage, a number that dwarfs the 48GB of my laptop’s contents in their entirety—so I decided to use a hard drive-to-USB 3.0 adapter to connect one to my laptop.

I opened “Disks”, but the hdd didn’t show up.

I looked up “external hard drive won’t show up Ubuntu” online, then opened several of the resulting webpages. At the advice of a commenter directed to a different commenter in a forum different from the Ubuntu Community Hub, I tried checking my file manager’s “devices” section… but my devices section wasn’t anywhere in my file manager! Oh well. Eventually, through a Reddit thread I chanced upon three different terminal-based ways of checking whether an external hard drive is being read. Full disclosure: I don’t know what these commands do, all I know is that they pull up stats for things I don’t understand.

The first way was entering sudo fdisk -l .
My hard drive wasn’t listed.

The second way was entering lsblk . Again, my hard drive wasn’t listed.

The third way was entering sudo dmesg | grep ATA- . My external hard drive showed up!

…Just kidding, in reality my hard drive didn’t show up.

The person to whom the Redditor suggested these things had results identical to mine, so the Redditor theorized that there was a problem with the hard drive’s hardware. The Redditor asked whether the disk was spinning and if the hard drive felt warm to the touch.
I don’t have any frame of reference for either of these hard drive-related things so I won’t comment on that, but I will say that I tested an additional three hard drives and none of them were being read either. Strange, especially since three different brands were tested: SanDisk, Seagate, and Hitachi.
For my situation, a “hardware issue” is a plausible explanation: all of my external hard drives were sourced from one cheap refurbished lot I purchased from eBay and my hard drive adapter was a $7-ish Amazon dongle. If the hard drives are formatted in a way not read by the live usb’s system, I’d be the last person to know.

That avenue now exhausted, I trudged back to the Clonezilla website. Somehow I understood its Linux instructions even less than before. And that’s when I quit the live Ubuntu usb environment.

These actions took up half of the 4 hours I spent troubleshooting. The other half was spent writing this down. Why? Because last month I was watching part of an 8-hour YouTube course for the CompTia ITF+ exam and within that part, the lecturer explained that documentation is very important when it comes to troubleshooting. This certification is apparently outdated now so please don’t ascribe too much weight to my words, but it’s the kind of computer advice that sounds timeless so I’m doing it anyway.

Besides, I need to get used to writing my attempts down and sharing the results. It’s better for other people and I think I’ve learned all that I could learn from solo investigation.

If there’s a moral to this story, I don’t know what it is.

12

Uh oh, I can’t mark more than one response as “Solved”. I’m sorry, people: I think you all contributed, but I cannot find a way to give the “Solved” to everyone and there’s no undo button. :slightly_frowning_face:

13

I undid it for you.

Best way is to simply thank those who helped and then we can close the topic for you.

Did you resolve the terminal issue?

14

No, but I assure you I’ll cleave mentions of my various technology issues into discrete questions. :slight_smile: If I can’t solve the terminal issue on my own, I’ll come here.

And @hdd-gehrke , don’t worry about answering that question about disk images: though I’m curious, I now know it’s irrelevant to my goal of backing my stuff and stuff’s folder hierarchy up. For any given project I can just type down the operating system information and program workflow in a .txt file, then store it with the project.

15

The best site for creating an Ubuntu live USB and using it to install is the official site at the link below.

https://ubuntu.com/tutorials/install-ubuntu-desktop#1-overview

The install options should at least have Erase disk and install which will overwrite anything on the selected drive and a manual install option where the user needs to make decisions. Sometimes an Install Alongside option will show but only if other operating systems are detected which they will not be if they are hibernated. A drive may also not be recognized if the hardware is bad which includes the physical drive, and adapter if one is used , the cable and the ports.

If you are interested in making an iso file, you might try penguins eggs which is used to remaster an installed system. I’ve not used it but it is highly recommended by other users who are experienced with linux and have used it, link below. It might be worth reading for you. Good luck.

https://penguins-eggs.net/