Set Up New Disk Partitions for Mountpoints in Alpine Linux

Guide to set up new disk partitions for mountpoints in Alpine Linux

Erika Tynn

• 2 min read
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Assumptions

Item Details
Operating system Alpine Linux with OpenRC
First disk /dev/sda — existing root disk
Second disk /dev/sdb — RAW, unused
New partition /dev/sdb1
Filesystem ext4
Mount point /mountpoint01
Persistence Automatically mount on boot using /etc/fstab
Partition table GPT

Inspect Existing Utilities / Install Missing Ones

Inspect which utilities are available

for cmd in fdisk sfdisk parted mkfs.ext4 blkid mount; do
    if command -v "$cmd" >/dev/null 2>&1; then
        echo "$cmd: available"
    else
        echo "$cmd: NOT FOUND"
    fi
done

The essential utilities are:

Utility Purpose Typical source
fdisk Create disk partitions BusyBox or util-linux
sfdisk Scriptable partition creation util-linux
mkfs.ext4 Create ext4 filesystem e2fsprogs
blkid Retrieve filesystem UUID BusyBox or util-linux
mount Mount filesystem BusyBox or util-linux
lsblk Inspect disks util-linux

Install additional packages, if needed

Package Why it is useful
util-linux Provides modern disk utilities, including partitioning and inspection tools
e2fsprogs Provides ext2/ext3/ext4 filesystem creation, checking, and maintenance tools 
apk add util-linux
apk add e2fsprogs

Create First New Partition

Check available disks and utilities

lsblk -o NAME,SIZE,TYPE,FSTYPE,MOUNTPOINTS

Create a GPT partition

This initialises a GPT partition table and creates one Linux filesystem occupying 10GiB of disk space.

💡
Warning: This overwrites the existing partition table. Use only after confirming /dev/sdb is the intended unused disk.
printf 'label: gpt\nsize=10GiB, type=L\n' | sfdisk /dev/sdb
lsblk /dev/sdb

Format partition

mkfs.ext4 -L data01 /dev/sdb1

For a dedicated Linux data disk, ext4 is generally the simplest and most dependable choice. For general storage, Docker volumes, application data, or backups on Alpine, choose ext4, unless there is a specific requirement for snapshots, compression, or other advanced features.

Filesystem Advantages Disadvantages Additional utilities
ext4 Mature, reliable, journaling, excellent Linux support Less advanced snapshot functionality e2fsprogs for formatting
XFS Strong for large files and high-throughput workloads Cannot shrink filesystem xfsprogs
Btrfs Snapshots, compression, checksums More operational complexity btrfs-progs
ext2 Simple, minimal overhead No journaling; less resilient to unexpected shutdowns e2fsprogs
FAT32 Broad compatibility 4 GiB maximum individual file size; no Unix permissions dosfstools

Create the mountpoint

mkdir -p /mountpoint01

Backup fstab, if needed

cp -p /etc/fstab /etc/fstab.bak

Configure the persistent mounting

blkid -s UUID -o value /dev/sdb1
UUID=$(blkid -s UUID -o value /dev/sdb1)
printf 'UUID=%s /mountpoint01 ext4 defaults 0 2\n' "$UUID" >> /etc/fstab

Mount and verify

mount /mountpoint01
df -h /mountpoint01

Append Second New Partition

Create new partition

Assuming you want a second 25GiB partition.

printf 'size=25GiB, type=L\n' | sfdisk --append --no-reread /dev/sdb
  • --append preserves existing partitions and adds another partition
  • size=25GiB specifies the desired size
  • type=L specifies a Linux filesystem partition
  • --no-reread suppresses the initial kernel partition-table reread check

Inform kernel about second partition

partx -a -n 2 /dev/sdb
lsblk /dev/sdb

partx is supplied by util-linux. It can register the new partition without requiring the existing partition to be unmounted.

If the kernel refuses to recognize the new partition, reboot before formatting. Do not format a partition until its device node and boundaries are correct.

Backup fstab, if needed

cp -p /etc/fstab /etc/fstab.bak

Format and mount the second partition

UUID=$(blkid -s UUID -o value /dev/sdb2)
printf 'UUID=%s /mountpoint02 ext4 defaults 0 2\n' "$UUID" >> /etc/fstab
mount /mountpoint02
df -h /mountpoint01 /mountpoint02