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#1 2025-11-15 09:39:09

drat
Member
Registered: 2025-11-15
Posts: 3

[SOLVED] fdisk stating disk in use while live booted

Hello all. I've booted from a live arch USB attempting to install Arch again on my machine. Upon entering fdisk, it gives a nice bright red warning:

This disk is currently in use - repartitioning is probably a bad idea. It's recommended to umount all file systems, and swapoff all swap partitions on this disk.

Output of lsblk:

NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0             7:0    0 961.5M  1 loop /run/archiso/airootfs
sda               8:0    0   1.4T  0 disk 
├─sda1            8:1    0   525M  0 part 
├─sda2            8:2    0 681.2G  0 part 
│ ├─Arch-lvRoot 253:1    0   120G  0 lvm  
│ └─Arch-lvHome 253:2    0   560G  0 lvm  
├─sda3            8:3    0    20G  0 part 
└─sda4            8:4    0   675G  0 part 
sdb               8:16   1  14.5G  0 disk 
└─sdb1            8:17   1  14.5G  0 part 
sr0              11:0    1   7.4G  0 rom  
nvme0n1         259:0    0 931.5G  0 disk 
├─nvme0n1p1     259:1    0   512M  0 part 
├─nvme0n1p2     259:2    0   400G  0 part 
│ ├─arch-lvRoot 253:0    0    40G  0 lvm  
│ ├─arch-lvHome 253:3    0   340G  0 lvm  
│ └─arch-lvSwap 253:4    0  19.5G  0 lvm  
├─nvme0n1p3     259:3    0    20M  0 part 
├─nvme0n1p4     259:4    0   529G  0 part 
└─nvme0n1p5     259:5    0   512M  0 part

Output of fdisk -l:

Disk /dev/sda: 1.36 TiB, 1500301910016 bytes, 2930277168 sectors
Disk model: WDC WD15EARS-60M
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0xa9fa3f7b

Device     Boot      Start        End    Sectors   Size Id Type
/dev/sda1             2048    1077247    1075200   525M ef EFI (FAT-12/16/32)
/dev/sda2          1077248 1429687500 1428610253 681.2G 8e Linux LVM
/dev/sda3       1429688320 1471631359   41943040    20G 82 Linux swap / Solaris
/dev/sda4  *    1471631360 2887208959 1415577600   675G  7 HPFS/NTFS/exFAT


Disk /dev/nvme0n1: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: WDS100T3X0C-00SJG0                      
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 33066E9C-700E-4C4A-B5E8-4C7746527A30

Device              Start        End    Sectors  Size Type
/dev/nvme0n1p1       2048    1050623    1048576  512M EFI System
/dev/nvme0n1p2    1050624  839911423  838860800  400G Linux LVM
/dev/nvme0n1p3  839911424  839952383      40960   20M Microsoft reserved
/dev/nvme0n1p4  839952384 1949345791 1109393408  529G Microsoft basic data
/dev/nvme0n1p5 1949345792 1950394367    1048576  512M Windows recovery environment


Disk /dev/sdb: 14.46 GiB, 15524167680 bytes, 30320640 sectors
Disk model: Patriot Memory  
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x604effcf

Device     Boot Start      End  Sectors  Size Id Type
/dev/sdb1  *     2048 30320607 30318560 14.5G  c W95 FAT32 (LBA)


Disk /dev/loop0: 961.48 MiB, 1008189440 bytes, 1969120 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/Arch-lvRoot: 120 GiB, 128849018880 bytes, 251658240 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/mapper/arch-lvRoot: 40 GiB, 42949672960 bytes, 83886080 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/Arch-lvHome: 560 GiB, 601295421440 bytes, 1174405120 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/mapper/arch-lvHome: 340 GiB, 365072220160 bytes, 713031680 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/arch-lvSwap: 19.5 GiB, 20937965568 bytes, 40894464 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

As you can see, nothing is mounted (besides loop0), and I've tried swapoff -a and umount -a (which unmounted loop0, same warning was present after the fact) for good measure. The pretty red text has been presented when entering fdisk with the following commands:

fdisk /dev/sda
fdisk /dev/nvme0n1

What I am trying to do is create new partition tables to overwrite all data on both of the aforementioned disks. Is there any reason these disks would be in use? I did not attempt to create a new table since I have not seen this warning before and wanted to resolve it, despite the fact that I am okay with losing all of the data. From what I've read trying to resolve this so far, it probably wouldn't let me create a new table even if I proceeded anyways.

Any information or a nudge in the right direction is appreciated smile

Last edited by drat (2025-11-15 21:11:04)

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#2 2025-11-15 10:06:37

mpan
Member
Registered: 2012-08-01
Posts: 1,593
Website

Re: [SOLVED] fdisk stating disk in use while live booted

I suspect that the problem comes from LVM volumes being automatically detected by Arch running from ISO. So you’ll have to unmount them first.

If your goal is to erase everything and the clean approach doesn’t work, a brutal method is erasing things and rebooting: using wipefs or removing partitions with fdisk itself while ignoring warnings. After the reboot they should no longer be detected.

Paperclips in avatars? | Sometimes I seem a bit harsh — don’t get offended too easily!

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#3 2025-11-15 18:25:40

drat
Member
Registered: 2025-11-15
Posts: 3

Re: [SOLVED] fdisk stating disk in use while live booted

mpan wrote:

I suspect that the problem comes from LVM volumes being automatically detected by Arch running from ISO. So you’ll have to unmount them first.

I don't understand what you mean by unmount in this context. The LVMs are not mounted to the live system, and the fstab is empty on the live image so none of those should have been automounted. Can you explain what you mean by this?

Using wipefs or otherwise completely erasing the data with something like shred is my next option, and the shred operation will take a while on a 1.5TB hdd.

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#4 2025-11-15 21:09:37

drat
Member
Registered: 2025-11-15
Posts: 3

Re: [SOLVED] fdisk stating disk in use while live booted

I have found a way to gracefully resolve this fdisk warning, and it was indeed due to the LVMs.

The idea of "unmounting the LVM" made me return to the basics and re-read about LVMs a little bit, and while I didn't consider the LVMs mounted, removing them resolved the warning.

lvremove /dev/Arch/lvHome
lvremove /dev/Arch/lvRoot

Note: this effectively deletes the logical volumes. In my case, I am okay with the data loss as I mentioned. After running these, I checked lsblk again, the LVs were gone, then rebooted. After reboot, I noticed the directory that contained the LVs (/dev/Arch/ [Capital "A" for the install on the sda device]) was gone also.

New lsblk output:

NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0             7:0    0 961.5M  1 loop /run/archiso/airootfs
sda               8:0    0   1.4T  0 disk 
├─sda1            8:1    0   525M  0 part 
├─sda2            8:2    0 681.2G  0 part 
├─sda3            8:3    0    20G  0 part 
└─sda4            8:4    0   675G  0 part 
sdb               8:16   1  14.5G  0 disk 
└─sdb1            8:17   1  14.5G  0 part 
sr0              11:0    1   7.4G  0 rom  
nvme0n1         259:0    0 931.5G  0 disk 
├─nvme0n1p1     259:1    0   512M  0 part 
├─nvme0n1p2     259:2    0   400G  0 part 
│ ├─arch-lvRoot 253:0    0    40G  0 lvm  
│ ├─arch-lvHome 253:1    0   340G  0 lvm  
│ └─arch-lvSwap 253:2    0  19.5G  0 lvm  
├─nvme0n1p3     259:3    0    20M  0 part 
├─nvme0n1p4     259:4    0   529G  0 part 
└─nvme0n1p5     259:5    0   512M  0 part

New fdisk -l output:

Disk /dev/sda: 1.36 TiB, 1500301910016 bytes, 2930277168 sectors
Disk model: WDC WD15EARS-60M
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0xa9fa3f7b

Device     Boot      Start        End    Sectors   Size Id Type
/dev/sda1             2048    1077247    1075200   525M ef EFI (FAT-12/16/32)
/dev/sda2          1077248 1429687500 1428610253 681.2G 8e Linux LVM
/dev/sda3       1429688320 1471631359   41943040    20G 82 Linux swap / Solaris
/dev/sda4  *    1471631360 2887208959 1415577600   675G  7 HPFS/NTFS/exFAT


Disk /dev/nvme0n1: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: WDS100T3X0C-00SJG0                      
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 33066E9C-700E-4C4A-B5E8-4C7746527A30

Device              Start        End    Sectors  Size Type
/dev/nvme0n1p1       2048    1050623    1048576  512M EFI System
/dev/nvme0n1p2    1050624  839911423  838860800  400G Linux LVM
/dev/nvme0n1p3  839911424  839952383      40960   20M Microsoft reserved
/dev/nvme0n1p4  839952384 1949345791 1109393408  529G Microsoft basic data
/dev/nvme0n1p5 1949345792 1950394367    1048576  512M Windows recovery environment


Disk /dev/sdb: 14.46 GiB, 15524167680 bytes, 30320640 sectors
Disk model: Patriot Memory  
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x604effcf

Device     Boot Start      End  Sectors  Size Id Type
/dev/sdb1  *     2048 30320607 30318560 14.5G  c W95 FAT32 (LBA)


Disk /dev/loop0: 961.48 MiB, 1008189440 bytes, 1969120 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/arch-lvRoot: 40 GiB, 42949672960 bytes, 83886080 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/arch-lvHome: 340 GiB, 365072220160 bytes, 713031680 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/arch-lvSwap: 19.5 GiB, 20937965568 bytes, 40894464 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Ran the fdisk command again on /dev/sda and the warning was gone smile

As this topic was created for that specific warning, and I have found a solution, I'll mark this as resolved. Thanks for the response mpan.

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