Equal disks; excludes reserves and formatting. RAID is not a backup. RAID 10 needs an even disk count; RAID 5 needs 3 or more and RAID 6 needs 4 or more.
Four 4 TB drives in RAID 5 provide 12 TB usable from 16 TB raw: 75% efficiency. This example excludes formatting, reserves and snapshots.
Equal disks; excludes reserves and formatting. RAID is not a backup. RAID 10 needs an even disk count; RAID 5 needs 3 or more and RAID 6 needs 4 or more.
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RAID 0: N×S; 1: S; 5: (N−1)×S; 6: (N−2)×S; 10: N×S/2.Equal disks; excludes reserves and formatting. RAID is not a backup. RAID 10 needs an even disk count; RAID 5 needs 3 or more and RAID 6 needs 4 or more.
All amounts use the same currency of your choice. These are estimates, not measurements or offers.
Compare theoretical NAS or storage-array capacity using equal drives. Enter one drive’s nominal capacity, not the array total. Spares, filesystem overhead and snapshots are excluded.
Actual free space will be lower because of device overhead. RAID 6 leaves 8 TB in the same example. Assess performance and rebuild time separately before choosing a layout.
No. Deletion and ransomware can affect the entire array. Keep independent copies and test restores.
The model assumes equal drives. Use the smallest size as a conventional approximation and check the vendor’s rules.
This model uses mirrored pairs with data distributed between them. It needs at least four drives and an even count.