/etc/fstab

The fstab (file system table) file is a configuration file that is used to configure how and where the main filesystems are mounted, especially at boot time.

Syntax
Each line of the fstab contains the necessary settings to mount one partition, drive or network share. The line has six columns, separated by whitespaces or tabs. The columns are as follows:
 * 1) The device file, UUID or label or other means of locating the partition or data source.
 * 2) The mount point, where the data is to be attached to the filesystem.
 * 3) The filesystem type.
 * 4) Options, including if the filesystem should be mounted at boot.
 * 5) Adjusts the archiving schedule for the partition (used by ). 0 disables, 1 enables the feature.
 * 6) Controls the order in which fsck checks the device/partition for errors at boot time. The root device should be 1. Other partitions should be either 2 (to check after root) or 0 (to disable checking for that partition altogether).

An example for the root device:

UUID, label
Instead of device files you can use persistent UUIDs and labels:

Services
The following OpenRC services read the fstab to mount or manage the filesystems.
 * localmount- Mount disks and swap according to fstab.
 * netmount - Mount network shares according to fstab.
 * fsck - Check and repair filesystems according to fstab.
 * root - Mount the root filesystem read/write.

These services supplement the fstab, if the filesystems are not explicit stated:
 * sysfs - Mount the filesystem.
 * devfs - Mount system critical filesystems in.

Check that they are enabled to start at boot time: