Start with these three steps
Keep the complete original pair
Retain both storage devices and the iMac’s repair history. If a shop replaced either part, ask for the removed component to be kept with the case.
Do not rebuild Fusion
Do not run diskutil resetFusion or approve a Fusion recreation while the old files matter. Apple’s rebuild procedure permanently deletes the data on both drives.
Record what changed
Note whether the problem followed a drive replacement, erase, macOS update or gradual slowdown. Photograph any existing Disk Utility view without altering the disks.
A single Finder disk can depend on two devices
Apple describes Fusion Drive as combining mechanical and flash storage for capacity and performance. Its smaller device should not be treated as an expendable accessory. The safe preservation decision is to keep the original pair available for assessment.
Do not guess which member holds a particular folder. Ask the assessor to identify the physical devices and the logical volume before trying to recover individual files. Label any already removed parts with their origin and removal date; avoid writing labels directly over connectors or exposed circuitry.
Sources: [1] Apple Support
A split-drive fix is not an undelete procedure
Apple’s split Fusion Drive article is a procedure for creating a working combined drive again. It explicitly warns that the operation deletes the contents of the member drives. Follow it only after the recovery question is resolved and wanted files are independently protected.
If you already ran a command or accepted a repair prompt, stop and write down exactly what it was. Include whether macOS was reinstalled and whether new accounts or files were created afterwards. That timeline is more useful than a vague description that the drive was repaired.
Sources: [2] Apple Support
Assess the condition of each member
A paired configuration can complicate an already failing disk. Repeated clicking or severe read errors from the mechanical side are reasons to stop further use. The absence of sound from the flash side does not establish that it is healthy.
Ask how each source would be preserved before any logical reconstruction. Keep an inventory of drive capacities and original component labels if a technician has already supplied them. Do not open the iMac merely to obtain those details; its model and service history are enough to start the conversation.
Define a useful result before authorising work
Identify the user accounts, libraries and date ranges that matter. For a family iMac, that might mean recovering the main Photos library and the last two years of Documents before less important downloads. Tell the assessor whether folder names and library organisation are essential.
Ask whether the proposed result is a set of verified files or a fully reconstructed volume, and whether missing or unreadable areas would be reported. A partial result can still be valuable, but its limits should be clear before you decide what further work to fund.
Sources: [5] Data Recovery Lab NZ
A realistic view of recovery
- Missing, damaged or overwritten portions of either member can limit reconstruction; preserving both does not guarantee a complete result.
- Recreating Fusion storage does not recover the previous logical volume.
Your questions, answered
Can I send only the large hard drive?
Does seeing two drives prove one has failed?
Can I replace the hard drive and reconnect the old SSD?
Need help with the original iMac?
Describe the model, what happened and which data matters. Data Recovery Lab NZ is an external specialist; ask it to confirm the assessment route for your exact device.
Sources & further reading
Primary and specialist guidance checked 27 October 2026. Features and instructions depend on the model and operating system.