Data Recovery Case File · NAS & Network Storage · Health Is the Problem
Recovering Deleted Files From a Working System Means Racing the System
His enquiry asks for something ordinary in an unusually difficult setting. Large backup files from a particular period, suspected to have been deleted from a network unit that "is a working storage solution" still in use for research. Nothing has failed, which is precisely the difficulty: a healthy system in daily service is writing continuously into exactly the space those deleted files occupy.
| Media | Multi-drive network storage unit in continuous operational use — historical backup files believed deleted; array healthy and serving |
| Reported situation | Network storage unit in continuous use as working storage · large backup files from a particular period sought · files believed to have been deleted at some point · unit operating normally · no fault present · recovery of deleted content requested |
| Fault class | Deleted content on a live array — no device fault; recoverability governed entirely by subsequent writing, which continues while the system serves |
| Equipment used | Continued operation identified as the sole factor reducing recoverability · unit taken out of service before assessment · every member imaged individually write-blocked · array assembled offline with parameters derived from the members · unallocated regions carved for large contiguous backup files |
The decode: why a working system is the harder case
Why deletion alone would be favourable: deleting a file removes its entry and marks its space available. The content stays where it was written until something is put in its place — which on an idle system means indefinitely.
Why a live system removes that grace: it writes constantly. Working storage in daily use allocates from the space that deletion released, which is precisely where those backups sit.
Why the file size cuts both ways: very large files occupy very large contiguous regions. That makes them easy to recognise and slow to be fully overwritten, since a great deal of new data is needed to cover one — but also means a partial overwrite ruins the whole file rather than part of a set.
Why the period matters more than the quantity: the longer ago the deletion, the more has been written since. Backups deleted years ago on a busy system are unlikely to survive; ones deleted recently may be largely intact.
What has to happen first, and it is the difficult part organisationally: the unit comes out of service. Every hour it continues serving reduces what can be recovered, and no technique compensates for content that has been written over.
Why that is a real cost to weigh: a working research store taken offline has consequences. The decision is whether the historical backups are worth the interruption, and it should be made deliberately rather than by delay.
Why delay is itself a decision: leaving the system running while the question is considered is choosing to reduce the prospects. The recoverable window is closing during the deliberation, which is worth saying plainly.
What the array configuration adds: content is distributed across members, so a deleted file's fragments sit on several drives. Recovery requires the array assembled before anything can be carved, which is done offline from images rather than on the live unit.
Why nothing is attempted on the unit itself: a live array cannot be searched safely, and any scanning tool run against it is another process writing. Members are imaged and the array reconstructed from copies.
What is worth checking before committing to any of it: whether the backups exist anywhere else — on tape, in an archive, or on a system that took a copy. An organisation that made backups often kept them somewhere, and that costs nothing to establish.
On the bench
Continued operation was identified as the sole factor reducing recoverability — deletion removing an entry and marking space available while content remains until replaced, so an idle system preserves indefinitely whereas working storage allocates from precisely that released space. Very large files occupy contiguous regions, making them recognisable and slow to overwrite completely, though partial overwriting ruins the whole file. The array was assembled offline with parameters derived from the members.
The outcome
Continued operation identified as the sole factor reducing recoverability, the unit taken out of service, and the array assembled offline from images. Free assessment, one fixed written figure including VAT, charged per drive. The decode: nothing has failed, and that is the difficulty. Your system is healthy and writing into exactly the space those deleted backups occupy — so the recoverable window closes while it serves, including while the question is being considered.
Recovering deleted files from a system still in use
Decide quickly whether to take it offline, because leaving it running while you consider is itself a decision that reduces the prospects. Deletion only removes the entry and marks the space available — content survives until something is written in its place, which on an idle system means indefinitely and on working storage means very little time at all. Large backup files help slightly, being contiguous and slow to overwrite completely, though partial overwriting ruins the whole file. Check whether copies exist elsewhere first, on tape or in an archive.
The window closes while it serves — call Manchester Data Recovery on 0161 871 0788; continued operation identified as the sole factor, members imaged individually, array assembled offline from images.
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Our case files are drawn from genuine enquiries received by our laboratory over the past ten years, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery procedure our engineers apply to that fault, using the equipment listed.