RAID cache protection failure
RAID controllers use battery- or capacitor-backed cache to protect acknowledged writes until they reach disk. A failed BBU, CacheVault module, flash backup unit, or cache memory fault can force write-through mode or leave protected cache awaiting recovery after an outage.
Understand the symptom
Broadcom documents that write-back cache risks data loss without working backup power and that controllers may switch to write-through when protection is bad. After an outage, cache can be marked preserved, dirty, lost, or discarded. Whether the array is consistent depends on which writes reached disk and whether cache contents remain recoverable.
What you may see
Cache protection is discharged, disconnected, expired, or faulty.
Firmware reduced performance to protect data from unbacked write cache.
The controller retained writes that have not yet been committed to members.
Recent acknowledged writes may not exist on disk, affecting metadata consistency.
Protect the source
Database journals, filesystem metadata, or parity updates may exist only in cache.
Firmware, keys, cache format, and array metadata must be compatible.
Another power event can create additional inconsistency.
Do this now
Save logs, cache status, BBU state, virtual-disk policy, firmware, and outage timeline.
Use a UPS and avoid repeated shutdowns while preserved cache is being assessed.
Do not separate or discard controller, cache, battery, capacitor, flash module, or keys.
Do not initialize, clear cache, replace members, or force write-back.
NEPFOSYS process
NEPFOSYS correlates protected-cache state, power history, RAID metadata, and filesystem symptoms.
Array disks are imaged before consistency work or virtual reconstruction.
Candidate array states are checked against databases, VMs, and priority files.
A clear next step
Start a case with the exact symptoms, incident timeline, prior attempts, encryption details, and the files that matter most. NEPFOSYS will route the case to the appropriate DFW intake or nationwide mail-in path.
Start with a case reviewQuestions, answered
Not by itself. Controllers often switch to write-through, but a power event with uncommitted cache can affect recent data.
Not before documenting and protecting it. Preserved cache may contain the newest acknowledged writes.
For an otherwise healthy system that may be maintenance, but after data loss or cache warnings the entire state should be reviewed first.
DFW local · Nationwide mail-in