The Backup Drive Failed Too

The decode

Two drives failing at once invites one question before two diagnoses. Simultaneous failure of a master and its backup can be coincidence, but it can also share a cause — a power event that struck both, similar drives of the same age wearing out together, or handling that affected the pair. Each drive is diagnosed on its own, but the possibility of a common cause is considered, because it can shape both the recovery and the advice that follows.

The faults are almost certainly different in detail, and each is imaged accordingly. A video recorder's internal drive and a removable external are different devices in different roles; even from one cause they may fail in different ways. So each is characterised separately — electronic, firmware, or mechanical — and imaged by its own fault, because the merged result can only be as good as each individual image allows.

Two damaged copies are a genuine advantage, and this is the encouraging part. When the same data exists on two drives, damage rarely falls in the same place on both. A region unreadable on the master may read cleanly on the backup, and vice versa. Comparing and merging the two images lets the good parts of each fill the other's gaps — so two partially recoverable drives frequently combine into one complete set, an outcome neither could give alone. His having kept a backup, even a failed one, is what makes this possible.

MP4 files add a second layer of resilience worth having. Video files carry strong signatures and internal structure, so they carve well and can be validated by playback. Where a file's container is damaged on both copies, it can often be rebuilt against a healthy reference clip from the same source — and where one copy's version is intact, that copy simply supplies the whole file. Assembled presentations built over years benefit from every one of these routes.

The whole job runs on images, never the failing originals. Both drives are imaged first, and all comparison, merging and repair happen on the images — protecting two already-fragile drives from further stress while the reconstruction proceeds.

The honest deliverable is the merged, validated set, with any true gaps named. Where a region failed on both copies at once, that footage may be incomplete — a real possibility, reported by file — but the two-copy merge is precisely what shrinks that category. The result goes to his new 2TB drive as playable, validated files, with the standing recommendation that a collection this valuable now lives in more than two aging places.

On the bench

Both drives were assessed independently on PC-3000 UDMA and their faults characterised, then each imaged under a hardware write-blocker — on DeepSpar Disk Imager with head mapping where degraded, with clean-air donor work under laminar flow where mechanical. The two images were compared and merged, good regions of one filling gaps in the other, and the MP4 files extracted and rebuilt, containers repaired against a reference where damaged and validated by playback to the new 2TB drive.

The outcome

Both drives imaged, the two copies merged to fill each other's gaps, and the MP4 collection rebuilt and validated to the new drive. The assessment is free and the quote is a single fixed figure inclusive of VAT; where a drive has to be opened, half of the parts and labour is payable up front and the balance falls due only on success — otherwise it is no recovery, no fee. The decode: your backup failing too was bad luck, but two damaged copies beat one — where the master couldn't be read, the backup often could, and merging them rebuilt the complete set.

Our case files are written up from genuine enquiries our lab has handled for customers across Staines, Surrey and the surrounding area, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery approach our engineers apply to that fault, using the equipment listed.