Data Recovery Case File · Desktop Externals & Aging Drives · The Window Is Reading
A Drive Out of Spare Sectors Can Still Give You What It Already Holds
His enquiry describes an asymmetry that names the fault. A secondary storage drive "visible and readable on my system, but appears unable to write anything; loading anything off it didn't fail, just took an absolute age and would hang." Reading works and writing does not — which is what a drive does when it has run out of the spare sectors it needs in order to write anywhere new.
| Media | 2TB secondary storage hard drive — reads completing with substantial delay and stalls; writes failing; reallocation reserve indicated as exhausted |
| Reported situation | Drive present and readable · content accessible with substantial delay · operations stalling during reads · writes not completing · drive used as secondary storage rather than for the system · contents required |
| Fault class | Reallocation reserve exhausted or protective read-only state entered — read path functional while write path unavailable; reading the operation to spend the remaining window on |
| Equipment used | Read and write asymmetry interpreted as reserve exhaustion or protective state · self-monitoring statistics read for reallocated and pending counts · no further use permitted during the available window · imaged write-blocked under strict per-sector timeouts with retries capped |
The decode: why one direction works and the other does not
What a drive does when it writes to a failing sector: detects the problem and relocates the data to a spare sector held in reserve, remapping the address so that everything continues to work. That reserve is finite, set aside during manufacture, and it is consumed as degradation proceeds.
What happens when the reserve is gone: the drive meets a failing sector and has nowhere to put the data. The write cannot be completed and cannot be worked around, so it fails — while reading data already recorded elsewhere carries on working.
Why some drives go further: firmware may deliberately enter a protective read-only state once degradation passes a threshold, refusing writes to prevent further loss. Either way the behaviour is identical, and either way the message is the same one.
What that message is: the drive can still return what it holds and cannot accept anything more. Which is, as it happens, exactly what he needs from it.
What the slowness and stalls indicate: reads that are succeeding on retry. A marginal sector fails, the drive tries again, and eventually returns the data — which is why loading takes an age rather than failing outright, and why it hangs at particular moments.
Why that is nevertheless a working read path: difficult and impossible are different. Data coming back slowly is data coming back, and a capture with capped timeouts avoids most of the waiting his ordinary use is enduring.
What the drive's own statistics will confirm, and they are free to read: a reallocated count at or near the reserve's capacity, and a pending count showing sectors detected and not yet relocatable. The second figure is the one that matters, because it counts what is currently failing.
What must happen now, and his configuration makes it easy: the drive is not the one his system runs from. It can be disconnected entirely without disrupting anything, which stops all incidental access while a capture is arranged — and every access spends part of a window that is not renewable.
On the bench
The read and write asymmetry was interpreted as reserve exhaustion or protective state — a drive relocating data from failing sectors to a finite reserve during writes, which fails once that reserve is consumed while reading already-recorded data continues, some firmware additionally entering a deliberate read-only state past a degradation threshold. Self-monitoring statistics were read for reallocated and pending counts, and imaging performed under strict per-sector timeouts with retries capped.
The outcome
The asymmetry read as reserve exhaustion, monitoring statistics confirmed, and the drive imaged under capped timeouts. Free assessment, one fixed written figure including VAT; where a drive has to be opened, 50% of parts and labour is payable upfront with the balance only on success — otherwise no recovery, no fee. The decode: reads working while writes fail is a drive with no spare sectors left to relocate into. It is telling you it can still return what it holds and cannot take anything more — which is exactly what you need from it.
Drive that reads slowly and refuses to write
Disconnect it and arrange a capture — that asymmetry means the reading window is open and every incidental access spends part of it. A drive relocates data from failing sectors into a finite spare reserve when it writes, so once that reserve is exhausted, writes fail while reads of already-recorded data keep working; some firmware also enters a deliberate read-only state past a degradation threshold. The slowness and stalls are reads succeeding on retry, which is difficult rather than impossible. Check the drive's own reallocated and pending counts too — the pending figure counts what is currently failing.
Disconnect it now — call Easy Data Recovery on 028 9002 0144; asymmetry read as reserve exhaustion, monitoring statistics confirmed, imaged under strict per-sector timeouts with retries capped.
Request a quote online →
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.