HFS Plus catalog recovery
The HFS Plus catalog file is a B-tree containing file and folder names, hierarchy, IDs, metadata, and initial extent information. Damaged nodes can make directories disappear, produce invalid record counts, or prevent the volume from mounting.
Understand the symptom
HFS Plus stores hierarchy in catalog B-tree records keyed by parent folder ID and name. Recovery compares header, index, leaf, map nodes, thread records, CNIDs, extents overflow, allocation bitmap, journal, and file content to rebuild paths while avoiding stale or duplicate records.
What you may see
fsck_hfs reports B-tree node, key order, link, or record-count errors.
macOS cannot traverse the catalog to expose a consistent directory tree.
Catalog relationships no longer map names and parent IDs reliably.
Each pass encounters additional tree or allocation inconsistencies.
Protect the source
A consistent new tree may omit files whose hierarchy cannot be proven.
Blocks may be marked free or reassigned while older catalog evidence is lost.
Image unstable drives before reading every B-tree node and data extent.
Do this now
Do not erase, reinstall, rebuild the catalog, or continue using the volume.
Save Disk Utility and fsck_hfs output, volume UUID, Mac model, failure trigger, and last working state.
Preserve partitioning, headers, journal, and every special file before reconstruction.
Retain valid passwords, recovery keys, and the original Mac hardware when FileVault is involved.
NEPFOSYS process
NEPFOSYS maps catalog nodes, keys, CNIDs, threads, extents, and allocation evidence.
Surviving records and file content are correlated on the image without editing the source.
Recovered data is checked for readable content, forks, names, and reconstructed folder relationships.
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
It is the special file that stores the volume's file and folder hierarchy, names, IDs, and key metadata.
Sometimes it can restore consistency, but it may remove ambiguous records. Image the device first when the files matter.
Not necessarily. Data extents may remain even when names and directory relationships need reconstruction.
DFW local · Nationwide mail-in