Which directory provides a systematic link to storage devices by their manufacturer ID?

The directory that provides a systematic link to storage devices by their manufacturer ID is indeed /dev/disk/by-id. This directory contains symbolic links to storage devices that are named based on their identifiers, which often include the manufacturer's name or the device's serial number. This is particularly useful for identifying devices uniquely in a way that is not dependent on the physical order of the devices or how they are connected to the system.

For instance, if a user had multiple disks from the same manufacturer, /dev/disk/by-id would allow them to differentiate between those disks by their unique identifiers, making it easier to manage storage, particularly in environments with multiple drives.

The other options serve different purposes. For example, /proc/mounts displays information about currently mounted file systems, while /dev/disk/by-path shows the devices linked by their connection path in the hardware hierarchy. /dev/disk/by-uuid links the devices by their universally unique identifiers, which is another way to identify devices but does not include the manufacturer ID as part of its naming convention.