Lab 14.1: Mount a USB disk and an ISO file, then remove them safely

Goal

Practise the full life of removable media on server1: find a new disk, mount it, copy files to it, fix a "target is busy" error, and read an ISO file. No real USB stick is needed — you add a small virtual disk.

Before you start

server1 with RHEL 10 (or CentOS Stream 10 / AlmaLinux 10) and root access.
Add a new empty virtual disk of 1 GiB to server1 (in virt-manager: Add Hardware → Storage, bus USB if you can choose, else VirtIO). It plays the USB stick.
An ISO file on server1, for example the RHEL 10 DVD ISO in /root/. Any ISO works.

Tasks

Find the name of the new disk. Write down its size and whether the kernel sees it as removable.
Make one partition on the new disk that uses the whole disk, and format it as vfat with the label LABSTICK.
Mount it on /mnt/usb so that the user student owns all files on it.
As student, copy /etc/os-release to the stick.
Open a second shell, cd /mnt/usb in it, and try to unmount the stick in the first shell. Find the reason for the error and fix it, then unmount.
Mount the ISO file read-only on /mnt/iso and list the folders in it. Then unmount it.

Check your work

#lsblk -f
#findmnt /mnt/usb
$ls -l /mnt/usb/os-release
#findmnt /mnt/iso

lsblk -f shows the partition with FSTYPE vfat and LABEL LABSTICK.
While mounted, ls -l shows student as the owner of os-release.
After the last task, findmnt /mnt/usb and findmnt /mnt/iso print nothing.

Hints

Show the hints

lsblk before and after you add the disk: the new name is the one that appears.
parted /dev/sdX mklabel msdos mkpart primary fat32 1MiB 100% makes the partition in one line.
vfat has no Linux owners. The mount options uid= and gid= set them.
lsof /mnt/usb or fuser -vm /mnt/usb shows who keeps the folder busy.

Solution

Show the solution

Compare the disk list. Here the new disk is /dev/sda (it can be /dev/vdb on VirtIO).
```
#lsblk -o NAME,SIZE,RM,TYPE
```

Partition and format it.

#parted -s /dev/sda mklabel msdos mkpart primary fat32 1MiB 100%
#mkfs.vfat -n LABSTICK /dev/sda1

Mount it for student (UID and GID 1000 on most test systems; check with id student).
```
#id student
#mkdir -p /mnt/usb
#mount -o uid=1000,gid=1000 /dev/sda1 /mnt/usb
```

Copy the file as student.

$cp /etc/os-release /mnt/usb/
$ls -l /mnt/usb

The second shell is inside the folder. Find it, leave the folder there, then unmount.
```
#umount /mnt/usb
#fuser -vm /mnt/usb
#umount /mnt/usb
```

Mount the ISO read-only with a loop device.

#mkdir -p /mnt/iso
#mount -o loop,ro /root/rhel-10.0-x86_64-dvd.iso /mnt/iso
#ls /mnt/iso
#umount /mnt/iso

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Mount a USB disk and an ISO file, then remove them safely