Manual method
Preserve chosen files from a mounted NAS or external disk onto another independent storage device.
- Connect the source drive or mount the authorized network share in Finder/File Explorer.
- Create a dated folder on a different destination disk; confirm which device is source and which is destination.
- Copy one top-level folder at a time and keep a batch log with source path, counts and errors.
- After copying, verify representative files and safely eject removable media.
Coverage and limitations: Two folders on the same drive are not two independent copies. RAID protects against some disk failures but is not the same as an independent archive. NAS snapshots/configuration require manufacturer-specific procedures.
Size and time to allow
Illustrative small / central / large case: 50 / 500 / 4000 GB (decimal GB). These are planning assumptions, not a measured average per person. 500 GB is a practical family-media archive scenario; a NAS can contain several terabytes.
Preparation: No provider queue. A network share is limited by local-network speed; USB disks by disk/interface speed. At an effective 100 MB/s, 500 GB alone takes about 83 minutes before verification.
For the central 500 GB example, network transfer alone is approximately:
| Connection | Estimated transfer |
|---|---|
| 10 Mbps | 158.7 hours |
| 50 Mbps | 31.7 hours |
| 100 Mbps | 15.9 hours |
Assumes 70% sustained use of the stated connection. Provider throttling, many small files, retries, local extraction and copying add time. For online backup use your upload speed. These are not estimates of the provider’s preparation queue. See calculation and large-file advice.
Store and verify the archive
Use an external SSD or hard drive as the main archive. A USB key is suitable for a selected transfer copy, but capacity and sustained speed can be limiting. Keep a second encrypted copy on a separate drive or in private online backup.
Create nas_external_drives/YYYY-MM-DD/originals/, preserve the untouched download, and extract a separate working copy when needed. Allow extra free space for archive plus extraction; compressed text can expand far beyond twice its size. Record account/scope, export date, date coverage and missing items in a local README without passwords.
Verify total bytes and checksums between independent devices, then open the destination with the source disconnected. Reopen a sample from the second copy before deleting or replacing any source. Storage choices and verification.
Sources and review
Public documentation was reviewed on 27 October 2026. No signed-in export or restoration was performed. Account options and availability can change; follow the current provider instructions.