How to Expand Storage on a Synology NAS

More capacity starts with the existing layout

A Synology NAS can eventually run short of space, but replacing a drive is not automatically a safe or complete upgrade. Check the exact model, DSM version, storage-pool type, drive health, and current backup before changing hardware.

Choose compatible drives

Use the model’s compatibility guidance for the interface, form factor, and supported capacity. The original article incorrectly implied that any Synology NAS supports SATA, SAS, and SSD options interchangeably. It also confused physical fit with the capacity needed for expansion.

Choose the supported expansion method

Depending on the model and RAID layout, you may be able to add drives to empty bays or replace existing drives with larger ones. Some layouts need several replacements before extra capacity becomes usable. Read Synology’s expansion guide and the drive-replacement procedure for your setup.

Protect the data first

Verify a separate backup and identify the intended drive. RAID redundancy is not a backup. If the pool is already degraded or reports failing disks, resolve that situation before treating it as a routine capacity upgrade.

Replace, repair, then expand

For a supported redundant pool, replace drives one at a time and let repair or rebuilding complete before proceeding. Whether the NAS should be powered down depends on its hardware and supported procedure. Don’t pull multiple drives on the assumption that the system will automatically add them back.

Storage-pool expansion and volume expansion are related but distinct operations. Check both in Storage Manager. A detected disk isn’t proof that the volume has grown.

Verify the result

Confirm pool health, usable capacity, file access, and the next backup. Restoring a backup is required only if your chosen procedure calls for it or recovery is needed; it isn’t an automatic final step for every successful expansion.