mars-nwe/doc/NWFS_SALVAGE_COMPRESSION_TOOLS.md

NWFS salvage, stream, compression and tool roadmap

This note records the storage-backend decisions made after the NSS Unicode, namespace and public-core audits. It is a design note only; it does not change runtime behavior.

Salvage authority

Long-term salvage state should be driven by NetWare/NSS-shaped metadata, not by private JSON sidecars.

Target authority order:

.recycle payload                 => deleted payload storage / Samba compatibility
netware.metadata on payload      => authoritative deleted-file metadata
.salvage JSON                    => legacy transition only, then remove

.recycle remains because it matches existing MARS-NWE behavior and Samba vfs_recycle interoperability. The goal is not to move deleted payloads into .nwfs_streams and not to replace the backend with the NSS ZLSS purge tree. The goal is to make the recycled payload itself carry the NetWare/NSS deleted metadata needed for NCP salvage, backup tools and restore.

New code should not create another private salvage metadata database. Use or extend netware.metadata for the deleted-file view.

Samba recycle interaction

The Samba 4.23.6 vfs_recycle module was checked. Its normal recycle path uses SMB_VFS_NEXT_RENAMEAT() to move the file into the repository. It does not copy the file and then copy xattrs. For the normal same-filesystem recycle case, Linux xattrs remain attached to the inode across the rename, so an existing netware.metadata xattr is preserved when Samba moves a file into .recycle.

If Samba cannot rename into the recycle repository, that module falls back to the normal unlink path rather than creating a copied recycled payload. In that case there is no recycled file for MARS-NWE to salvage.

Therefore:

• files moved to .recycle by MARS-NWE should have complete deleted metadata;
• files moved to .recycle by Samba should retain existing xattrs;
• files manually copied into .recycle without netware.metadata are not valid NetWare salvage objects by default.

Do not add automatic synthetic salvage fallback for missing metadata. If an administrator wants to repair such files, provide an explicit tool command later.

Delete, scan, recover and purge target flow

Delete through MARS-NWE/NCP:

1. move the payload into .recycle
2. set/update netware.metadata on the recycled payload
3. mark the object as deleted/salvageable using NSS-shaped fields
4. do not write a new .salvage JSON sidecar once migration is complete

Metadata on the recycled payload should include at least:

zNTYPE_DELETED_FILE-compatible deleted type
DeletedPersistentParentEntry_s-compatible delete time and UserID_t
original parent identity
original DOS/LONG/MAC/UNIX names where available
original attributes/times/owner/archive/modifier fields
trustees / inherited-rights mask where available
stream, EA and compression references later

NCP scan:

scan .recycle
read netware.metadata from each recycled payload
return official salvage replies from that metadata
ignore entries without valid deleted metadata

Recover:

move/copy the payload back through existing MARS-NWE file mechanisms
clear or normalize the deleted state in netware.metadata
restore names, attributes, times, trustees, AFP hints, streams, EA and compression state

Purge/final delete:

remove the .recycle payload
remove associated NWFS internal stream/EA/compression backend entries when present

Legacy .salvage JSON:

read only for migration or old-install cleanup
migrate to netware.metadata where possible
stop writing new sidecars
remove yyjson once no other required consumer remains

.nwfs_streams scope

.nwfs_streams is for internal NWFS stream-like storage, not for the main Samba-compatible recycle payload.

Target layout:

/export/SYS/.nwfs_streams/<stable-file-id>/primary
/export/SYS/.nwfs_streams/<stable-file-id>/resource
/export/SYS/.nwfs_streams/<stable-file-id>/ea
/export/SYS/.nwfs_streams/<stable-file-id>/compression

Rules:

• <stable-file-id> is a MARS/NWFS/NSS-shaped stable file ID stored in netware.metadata.
• Do not use Linux inode numbers as the authoritative ID.
• Do not use the visible filename as the authoritative ID.
• Do not expose .nwfs_streams through normal NCP namespace calls.
• Compression state belongs in metadata/stream descriptors, not in a compressed_ filename prefix.
• A compressed stream backend is keyed by the stable file ID; the backend name is not the user's DOS/LONG/MAC/UNIX filename and should survive rename/move.

Example:

NCP-visible file:
  SYS:FOO\BAR.TXT

Linux namespace payload while live and uncompressed:
  /export/SYS/FOO/BAR.TXT

Internal compressed stream backend after future compression work:
  /export/SYS/.nwfs_streams/0000000000001234/compression/primary

Authoritative metadata:
  netware.metadata:
    file_id = 0000000000001234
    primary stream storage = compressed
    logical_size = ...
    compressed_size = ...
    algorithm = netware/nss

Salvage may reference stream snapshots in .nwfs_streams, but the deleted primary payload remains in .recycle for Samba compatibility.

Compression storage model

Linux filesystems such as ext3 and XFS do not provide a portable NSS-compatible transparent compression model. MARS-NWE should not depend on host-FS-native compression for NetWare/NSS semantics.

Compression belongs to future libnwfs work:

Phase 1: import/adapt NSS compression algorithm sources
Phase 2: add NWFS stream backend for compressed payloads
Phase 3: make NCP read/write paths transparently de/compress when enabled
Phase 4: add compression manager/accounting/state for monitor endpoints

When a compressed file is recycled, the .recycle payload should be written in uncompressed form. Samba and host-side tools know only the recycle repository and normal Linux file contents; they do not know how to read a private NWFS compressed stream backend. Therefore future delete/recycle handling must materialize the primary data stream before or during the move to .recycle, then record the former compression state in netware.metadata so NCP recover can recreate the compressed state later if the volume policy requires it.

live compressed file:
  /export/SYS/FOO/BAR.TXT                         # namespace object
  /export/SYS/.nwfs_streams/<file-id>/compression/primary
  netware.metadata: primary stream storage = compressed

recycled file:
  /export/SYS/.recycle/<user>/FOO/BAR.TXT         # uncompressed payload
  netware.metadata: deleted metadata + previous compression descriptor

Do not expose compressed bytes directly in .recycle. .recycle is the Samba-compatible payload backend; .nwfs_streams is the private live/future stream backend.

Compression-related NCP providers must use real libnwfs state, not fake data:

decimal 90/12  == wire/code 0x5a/0x0c  Set Compressed File Size
decimal 123/70 == wire/code 0x7b/0x46  Get Current Compressing File
decimal 123/71 == wire/code 0x7b/0x47  Get Current DeCompressing File Info List
decimal 123/72 == wire/code 0x7b/0x48  Get Compression and Decompression Time and Counts
decimal 22/51  == wire/code 0x16/0x33  Extended Volume Info compression counters

Tool roadmap

Future host tools should operate on netware.metadata and libnwfs helpers, not on private JSON sidecars.

nwsalvage

nwsalvage --help
nwsalvage --list <volume-or-path>
nwsalvage --info <recycled-file>
nwsalvage --restore <recycled-file>
nwsalvage --restore-to <recycled-file> <target>
nwsalvage --finaldelete <recycled-file>
nwsalvage --purge <volume-or-path>
nwsalvage --verify <volume-or-path>
nwsalvage --repair-minimal <recycled-file>   # explicit admin action only

--repair-minimal must never run implicitly during normal salvage scan. It is only for an administrator who intentionally wants to turn a manually copied .recycle file into a NetWare salvage object.

nwmetadata

nwmetadata --dump <file>
nwmetadata --verify <file>
nwmetadata --set-deleted <file>
nwmetadata --clear-deleted <file>
nwmetadata --repair-minimal <file>

nwcompress

nwcompress --help
nwcompress --info <file>
nwcompress --compress <file>
nwcompress --uncompress <file>
nwcompress --verify <file>
nwcompress --list <volume-or-path>

nwstreams

nwstreams --help
nwstreams --list <file>
nwstreams --dump <file> <stream>
nwstreams --extract <file> <stream> <out>
nwstreams --remove <file> <stream>

nwea

nwea --help
nwea --list <file>
nwea --dump <file>
nwea --set <file> <name> <value>
nwea --remove <file> <name>

yyjson removal target

yyjson is currently part of the tree because .salvage JSON sidecars exist. Once new deletes stop writing .salvage JSON, legacy sidecar migration is complete, and no other required code uses yyjson, remove the third_party/yyjson submodule/build dependency.

Do not remove yyjson in the same patch that changes salvage semantics. First move the authoritative model to netware.metadata, migrate or retire the JSON reader/writer path, then remove yyjson as a cleanup patch.