ASUSTOR NAS Storage: ADM, RAID Options, and Why Overhead Varies
ASUSTOR ADM storage overhead varies by model and firmware version. No vendor-published overhead figure exists, making ASUSTOR a Tier C brand in our evidence system. Use Exact Mode for the most accurate capacity estimate.
See exactly how much usable storage your configuration delivers.
ASUSTOR ADM Storage
ASUSTOR's ADM operating system creates storage pools and volumes using standard Linux mdraid. The system partition and swap overhead varies by device model. ASUSTOR has not published a consistent per-drive or flat figure in its documentation.
Quick Mode shows "system overhead varies" for ASUSTOR and recommends Exact Mode. In Exact Mode, you can enter the system-reserved value your ASUSTOR NAS reports in Storage Manager after setting up your array.
RAID Options on ASUSTOR
- RAID 5. (n−1) drives usable. Three drives minimum.
- RAID 6. (n−2) drives usable. Four drives minimum.
- RAID 1. Mirror. Single drive capacity usable.
- RAID 10. Half capacity, strong performance.
- JBOD / RAID 0. No redundancy.
ASUSTOR ADM supports Btrfs and ext4. Btrfs is the default on recent ADM versions (~4% metadata overhead), ext4 carries ~2%.
How to Get Exact Overhead for Your ASUSTOR
- Set up your array in ASUSTOR Storage Manager
- Note the "Total Capacity" and "Used" figures shown for the storage pool
- The difference between raw RAID capacity and reported pool size is your system overhead
- Enter this in the RAID calculator's Exact Mode for precise results
Frequently Asked Questions
Why doesn't the RAID calculator apply system overhead for ASUSTOR?
ASUSTOR has not published a consistent system overhead figure across its product range. Applying an estimate with no vendor backing would be misleading. Exact Mode is the honest approach. Enter the value your device actually reports.
Does ASUSTOR support expansion volumes?
Yes. ASUSTOR EZConnect and Storage Manager support adding drives to expand existing RAID 5/6 pools. The pool rebuilds while remaining accessible.