The comment on the bridge-degradation branch in handle_read_error
claimed it matched the NOT_READY 04/3E sense signature, but
is_bridge_degradation() keys solely on a non-standard SCSI status byte
(anything that is not GOOD/CHECK CONDITION/TRANSPORT FAILURE) and
ignores sense_key/ASC/ASCQ. A real 04/3E bad-sector error arrives as
CHECK CONDITION (0x02), so it never took this branch — it falls through
to the generic NOT_READY retry. Rewrite the comment to describe the
status-byte condition the predicate actually detects, and drop the
parallel misleading note in the not_ready_err test helper.
Add a regression test asserting a NOT_READY 04/3E error is not
classified as bridge degradation and routes to the NOT_READY retry
(3 s pause) rather than the bridge cooldown (15 s pause).
Spec-grounded unit tests for the silent-corruption surfaces, each verified to
fail under a targeted source mutation (no vacuous tests).
udf (10): Extended-AD 20-byte stride + extent LBA at off+12, type-1 sparse
extents skipped not emitted, zero-length type-0 terminator, continuation-loop
bound (anti-hang), UTF-16BE and 8-bit name decoding, FID L_IU offset, parent
(..) FID skip, d-string length-byte cap. Locks the spec branches a future
allocation-descriptor refactor must not silently break.
recovery (9): Pass-N damage-skip range bounds (forward/reverse cursor stays in
range), one-quarter-of-remaining skip cap, below-threshold no-op, work-done
accounting, and bridge-degradation retry-to-budget fall-through.
Library-wide review-and-fix pass: tightened AACS keydb/handshake/variant
handling and trailing-partial-unit policy, corrected MPLS mark offset and
added UDF allocation bounds, hardened the mux/codec framing and M2TS paths,
guarded SCSI READ CAPACITY short transfers and unified error mapping, added
overflow guards on untrusted disc input, and made prefetch shutdown
deterministic. Release profile now builds with thin LTO + single codegen unit.
Rewrites the Pass 1 wedge handling from "slow skip after the drive
has already wedged" to "prevent the wedge transition in the first
place." Driven by 2026-05-11 empirical data: the BU40N transitioned
into IllegalRequest fast-fail mode at exactly 7 medium errors in
6.5 seconds (~1 read/sec retry cadence). Once there, only physical
eject + reload clears it — 30s pauses + 1 GB jumps do not.
The fix is the user's mental model from that session:
"We can detect bad reads, failed reads, and asking to read again
fast after causes a wedge. We need to prevent the wedge in the
first place."
Two changes to the centralized error handler:
1. **`for_sweep().fast_jump_threshold = 1`** (was 4). Pass 1 now
JumpAheads on the FIRST outer-batch failure, not the 4th. The
drive never gets back-to-back retries at the same LBA in Pass 1
— every error → jump 64 MB forward + long cooldown. Pass N keeps
`fast_jump_threshold = u64::MAX` because retries on already-known-
bad LBAs are its whole job.
2. **`ZONE_ENTRY_COOLDOWN_SECS = 30`**. The FIRST error after a
clean run (when `consecutive_outer_failures == 1` and we're not
bisecting) uses this long pause instead of the standard 5 s
FAIL_PAUSE_SECS. Gives the BU40N's firmware / bridge internal
retry counters 30 s of breathing room before the next read,
preventing the "7 errors in 6.5 s" cascade. Subsequent errors
in the same zone use the standard 5 s pause (we've already
jumped past the initial damage; further errors mean we landed
in another bad cluster).
Pass N exempt from the zone-entry cooldown — `bisect_on_marginal=
true` skips the long-pause arm. Pass N's per-sector retries on
known-bad LBAs would multiply uselessly with 30 s/error.
Test updates: 4 tests' expected behavior changed under the new
policy. Renamed `pass_1_marginal_skips_instead_of_bisecting` →
`pass_1_marginal_jumps_immediately_not_bisecting`. Renamed
`pass_1_jumps_after_4_consecutive_outer_failures` →
`pass_1_jumps_immediately_on_first_outer_failure`. Updated
`both_passes_pause_on_failed_read_for_wedge_avoidance` (now
`pass_1_zone_entry_uses_long_cooldown` + `pass_n_pauses_uniformly_on_failed_read`).
Cost analysis:
- Clean disc (no errors): unchanged. 0% overhead.
- Lightly damaged (1-2 zones): +30 s per zone = ~1 min total. Fine.
- Heavily damaged (10+ zones): +5+ min total. The trade for never
wedging the drive and getting a usable Pass N afterwards.
Expected behavior on the next damaged-disc rip:
- Pass 1 hits damage at LBA X → jumps 64 MB forward immediately,
pauses 30 s
- Drive's firmware never accumulates the retry pressure that triggers
IllegalRequest fast-fail
- bytes_maybe accumulates faster (we skip more), but Pass N picks up
the slack with proper per-sector recovery — and Pass N can actually
RUN because the drive isn't wedged
User's design call after watching the avoidance work prevent a wedge
on the live rip (no wedge events across 6 read errors): "Pass N
and 1 should both be very very similar in recovery. almost identical
just smaller sectors imo in pass n. pause times the same imo as a
failed read is a failed read."
The error-handling code path was already centralized (one
handle_read_error fn, called by both Disc::sweep and Disc::patch).
The TUNING was split — Pass 1 used 5 s inter-error pauses + a
wedge-skip-and-continue policy; Pass N used 1 s pauses + immediate
AbortPass on HARDWARE_ERROR / ILLEGAL_REQUEST. That asymmetry made
Pass N vulnerable to the same wedge that Pass 1's avoidance fixed.
Changes:
1. FAIL_PAUSE_SECS = 5 — single constant, applied uniformly to both
passes. Dropped PASS_1_FAIL_PAUSE_SECS and POST_FAILURE_PAUSE_SECS
in favor of one value. CONSECUTIVE_FAIL_LONG_PAUSE_SECS kept as a
distinct (but currently equal) value for future tuning escalation.
2. HARDWARE_ERROR / ILLEGAL_REQUEST path is now symmetric:
- Pass 1: JumpAhead WEDGE_JUMP_SECTORS (1 GB) + WEDGE_PAUSE_SECS
cooldown, mark skipped region NonTrimmed.
- Pass N: JumpAhead WEDGE_PASS_N_SKIP_SECTORS (64 sectors / 128 KB)
+ WEDGE_PAUSE_SECS cooldown. Pass N's batch=1 means a 1 GB skip
would abandon the entire current NonTrimmed range; small skip
moves past the bricked LBA + buffer, outer patch loop picks up
the next sector.
- Both share WEDGE_ABORT_THRESHOLD — same 16-skip budget before
real AbortPass on a permanently stuck drive.
3. wedge_skip / wedge_abort tracing logs now include `pass=1|N`
so post-mortems can see which pass hit the wedge condition.
Cost analysis:
Pre-reframe worry was "5 s × 5500 NonTrimmed sectors per Pass N
pass × 7 passes = 53 hours." Reality: most NonTrimmed sectors
recover on first or second retry, so most reads are successful and
pay 0 pause. The few that DON'T recover hit the 10-skip budget and
get marked Unreadable — bounded at 10 × 5 s = 50 s per truly-bad
sector. Worst-case Pass N pause overhead on a typical damaged disc
is single-digit minutes, not hours. And it's strictly cheaper than
the alternative (wedge kills the entire multi-pass recovery).
Tests:
- `both_passes_pause_on_failed_read_for_wedge_avoidance` — locks the
unified pause-tuning policy (was pass_1_pauses_briefly).
- `pass_n_hardware_error_also_skips_not_aborts` — was
`pass_n_hardware_error_still_aborts`. New behavior verified:
JumpAhead with WEDGE_PASS_N_SKIP_SECTORS + WEDGE_PAUSE_SECS.
- `pass_n_hardware_error_aborts_after_threshold` — new. Confirms
Pass N respects the same WEDGE_ABORT_THRESHOLD as Pass 1.
- pass_1_does_not_pause_on_skip is gone (it was the old "Pass 1
pause=0" assertion, irrelevant after the avoidance work).
Empirical validation: avoidance was already proven on a live rip
tonight — 6 read errors on a damaged disc, sense_family=Medium
throughout, wedge_count=0, Pass 1 continued cleanly past 40%
where it previously died at 48%. This commit extends the same
discipline to Pass N's recovery loop.
Precommit (cargo +1.86 fmt + clippy + test) green.
Adds the observability we need to debug wedge incidents from logs
alone — without needing to enable verbose TRACE-level SCSI tracing.
Goal stated by user: "when error occurs we can debug and code
correctly."
Pre-fix the WARN log on each read error showed only sense codes
and consecutive_failures. Missing: timing context (was the failed
read fast or slow?), gap to previous events (cumulative vs.
immediate failure?), and family transitions (did the drive just
flip into wedge mode, or has it been there?).
New fields on ReadCtx (no caller signature change):
last_success_at: Option<Instant>
last_error_at: Option<Instant>
last_error_family: Option<SenseFamily>
total_errors: u64
total_reads_ok: u64
zones_entered: u64
jumps_taken: u64
in_damage_zone: bool
New SenseFamily enum (NotReady / Medium / Hardware / IllegalRequest
/ Other) with is_wedge_family predicate.
handle_read_error WARN log now carries:
consecutive_failures
consecutive_outer_failures
ms_since_last_error NEW gap between this and previous error
ms_since_last_success NEW gap to last good read
total_errors NEW aggregate this pass
total_reads_ok NEW
wedge_count
sense_family NEW typed category, easier to filter
sense_key / asc / ascq (existing)
NEW WARN log "wedge_transition" fires once when the sense family
changes from non-wedge to wedge (Medium to Hardware/IllegalRequest).
That's the moment the drive's firmware flipped into fast-fail
mode. Single timestamped event in the log so post-mortems can
pinpoint the transition without scanning thousands of TRACE lines.
Worked example: if the next wedge incident shows
read_error ms_since_last_success=18234 ms_since_last_error=null
read_error ms_since_last_success=28000 ms_since_last_error=10000
read_error ms_since_last_success=43000 ms_since_last_error=68
(drive returned <100ms = wedge symptom)
wedge_transition errors_in_zone=5 ms_since_last_success=43000
we can immediately tell cumulative damage, 5 errors over 43 s,
drive went into fast-fail mode at the 5th. If instead we see
read_error ms_since_last_success=200 ms_since_last_error=null sense_family=Hardware
wedge_transition errors_in_zone=1
the wedge was triggered by ONE read at a physically-bricked LBA
(immediate fast-fail, no warm-up).
These two patterns demand different tuning responses (longer
pause vs. larger initial jump), and now we can distinguish them
from a single WARN log line each instead of needing TRACE
verbose for the whole rip.
Plus jumps_taken / zones_entered counters that feed an end-of-pass
INFO summary (PassSummary). Caller invokes pass_summary at sweep
end and logs structured stats: "Pass 1 saw N errors / M ok reads
/ K zones / J jumps". Single-line post-mortem for any rip.
No caller signature change (timing is internal to the handler;
end-of-pass summary is a new method callers opt into). Precommit
green; 433+ tests pass. Staged for the 0.18.10 release once we
have user-validation data on 0.18.9's avoidance tuning.
Complements the wedge-skip backstop (fbdb50c) with proactive
avoidance so we don't HIT the wedge in the first place. User's
take after seeing the Dune Pt 2 rip wedge at 48%: 'we shouldn't be
wedging.'
Empirical observations from the 23:09:12-23:09:55 wedge timeline:
5 read errors over 43 s, ~8 s apart (drive's own ECC recovery
takes 5-10 s per failure). Not 'hammering' in any usual sense,
but cumulative firmware-state buildup over 5 in-cluster errors
was enough to tip the BU40N into wedge mode at the 5th error.
Damage cluster spanned ~140 MB (LBAs 19.898M-19.965M). Current
damage-jump base of 256 sectors × batch=32 = 16 MB first jump,
doubling to 32 MB, 64 MB... Each jump landed BACK INSIDE the
140 MB cluster, exposing the drive to MORE in-cluster errors.
Two avoidance levers:
1. Inter-error pause on Pass 1 (PASS_1_FAIL_PAUSE_SECS = 5 s):
pre-fix Pass 1 ran pause_secs=0 on all errors to 'zoom past'
damage zones. Successful reads still zoom at zero pause — the
pause applies only to FAILED reads, giving the drive's firmware
cool-down between cluster exposures. Cost: ~5 s per scattered
failure (~30-60 s total on a damage cluster); trivial vs.
crashing the rip at 48%.
2. Larger damage-jump base (JUMP_BASE_SECTORS = 1024, up from
256): first jump at batch=32 now covers 64 MB instead of 16 MB,
second jump 128 MB instead of 32 MB. Two jumps clear 192 MB —
well past most single-cluster damage patterns. Smaller jumps
were landing inside the cluster and adding to the wedge counter.
Plus a halt-aware sleep helper (sleep_secs_or_halt) so the new
inter-error pause doesn't degrade halt response time. Halt poll
granularity 100 ms — halt fires within ~100 ms regardless of
remaining pause time. Updated three sleep call sites in disc/mod.rs
(SkipBlock pause, JumpAhead post-pause, Retry pause).
The wedge-SKIP backstop (fbdb50c) stays — combined with this
avoidance work, the flow becomes:
damage cluster encountered →
pause 5 s, mark NonTrimmed →
second failure →
pause 5 s, mark NonTrimmed →
...
threshold hit →
damage-jump 64 MB (clears 95% of clusters) →
if jump lands in another cluster: 128 MB next jump →
only if drive STILL wedges after all this:
wedge-skip kicks in (1 GB jump + 30 s cooldown × 16 budget)
Tests:
pass_1_pauses_briefly_on_skip_for_wedge_avoidance — locks the
new 5 s pause behavior in place (replaces the old pause=0 test).
integration test threshold bumped from 5 s to 60 s with comment
explaining the new bound is 'not infinite' rather than
'milliseconds-fast'.
All 433+ tests green on cargo +1.86 fmt + clippy + test.
Precommit green.
Pre-fix: when the drive returned HARDWARE_ERROR or ILLEGAL_REQUEST
during Pass 1 sweep, libfreemkv immediately returned ReadAction::
AbortPass. Autorip surfaced this as a fatal error and stopped the
rip at whatever progress percentage Pass 1 had reached — typically
40-50%. On a disc with one physical-damage cluster, the user would
see Pass 1 die at ~48% with the cryptic message 'E6000: <lba>
0x02/0x04/0x3e' and have no rip output to work with.
Root cause analysis: BU40N firmware transitions into a fast-fail
state when it hits cumulative read failures in a small LBA range —
returns HARDWARE_ERROR for every subsequent read near that LBA, even
sectors that aren't physically damaged. Per project docs 'Bad-sector
handling' rule #2, 'Recovery requires eject+reload OR significant
cool-down.' Aborting on first wedge throws away the rest of the
disc; the right response is to SKIP the wedged region (mark as
NonTrimmed for Pass N), pause for drive cooldown, and continue.
Fix: in handle_read_error, the HARDWARE_ERROR / ILLEGAL_REQUEST arm
now branches on bisect_on_marginal:
Pass 1 (bisect_on_marginal=false): JumpAhead with WEDGE_JUMP_SECTORS
(1 GB at 2048 bytes/sector) and WEDGE_PAUSE_SECS (30 s cooldown).
Tracks wedge_count in ReadCtx; resets on any successful read.
Truly aborts only after WEDGE_ABORT_THRESHOLD (16) consecutive
wedges with no good read in between — generous enough to clear
most physical-damage clusters, bounded enough to not loop forever
on a permanently bricked drive.
Pass N (bisect_on_marginal=true): unchanged AbortPass. Pass N's
job is single-sector recovery; if the drive won't talk near a
specific LBA, skipping doesn't help. Pass N exits and lets the
outer layer decide retry/eject/surface.
5 unit tests cover the new policy:
pass_1_hardware_error_jumps_ahead_not_aborts — JumpAhead emitted
with correct sectors+pause, wedge_count incremented.
pass_1_hardware_error_aborts_after_threshold — AbortPass kicks in
on the WEDGE_ABORT_THRESHOLD-th consecutive wedge.
pass_1_good_read_resets_wedge_count — on_success clears
wedge_count; subsequent wedge gets fresh skip budget.
pass_n_hardware_error_still_aborts — Pass N's AbortPass behavior
intact.
pass_1_illegal_request_also_routes_to_wedge_skip — both wedge
sense families get the skip treatment.
Impact: on the Dune Pt 2 disc that consistently wedged at 48%
(physical damage at LBA ~19.9M), Pass 1 will now jump ahead 1 GB
on the wedge, give the drive 30 s cooldown, and continue scanning
the rest of the disc. The damaged region becomes Pass N's job to
revisit. Worst case if the drive stays wedged: 16 GB of NonTrimmed
disc area before honest AbortPass.
Precommit (cargo +1.86 fmt + clippy + test) green; 430 passing.
Pass 1 sweep was grinding through damage zones because the marginal-
media handler returned `Bisect` for every failed 32-sector batch —
forcing 32 single-sector reads per bad block at ~5s each on a real
BU40N-vs-Dune-Pt-2 trace. AND the JumpAhead trigger required a 16-
block damage window to fill before firing, so entry into a
contiguous damage zone took ~40 minutes of grinding before the
first jump fired. Architecturally wrong: Pass 1's job is "fast and
accurate, get the most data in the shortest time." Bisection +
recovery is Pass N's purpose-built role.
ReadCtx now carries two new fields:
- `consecutive_outer_failures: u64` — outer-batch failures since
last outer success. Bisect inner failures don't count.
- `bisect_on_marginal: bool` — whether to return Bisect on a
marginal-media batch failure.
- `fast_jump_threshold: u64` — outer-failures count that triggers
JumpAhead before the damage window has filled.
`for_sweep` (Pass 1) sets `bisect_on_marginal=false`,
`fast_jump_threshold=4`, and zeroes the post-failure pause. Failed
batches become SkipBlock → whole block NonTrimmed → advance, no
sleep. After 4 consecutive outer failures: JumpAhead with the
existing escalating multiplier.
`for_patch` (Pass N) sets `bisect_on_marginal=true`,
`fast_jump_threshold=u64::MAX`, keeps the original cooldown pauses.
Pass N's whole reason to exist is to grind on bad ranges with
proper recovery semantics — single-sector reads, 60s recovery
timeout, retry budget, escalating skip — and that's unchanged.
`on_success` resets `consecutive_outer_failures` only when not
bisecting, so a good single-sector read inside Pass N's bisect
doesn't pretend we've escaped the damaged batch.
Tests:
- `pass_n_marginal_with_batch_gt_1_bisects` — Pass N still bisects.
- `pass_1_marginal_skips_instead_of_bisecting` — Pass 1 doesn't.
- `pass_1_jumps_after_4_consecutive_outer_failures` — fast-entry.
- `pass_n_does_not_fast_jump` — fast-entry is Pass-1-only.
- `outer_success_resets_consecutive_outer_failures` — counter reset.
- `bisect_inner_success_does_not_reset_outer_counter` — semantics.
- `pass_1_does_not_pause_on_skip` — explicit zero-pause contract.
- `long_failure_streak_extends_pause_on_pass_n` — Pass N still
extends pauses on long failure streaks (renamed from the old
sweep-based test).
Integration test `test_disc_copy_marks_failed_ecc_blocks_as_nontrimmed`
updated: it used to assert Pass 1 recovers all sectors via bisect
(bytes_good=total). New contract: Pass 1 marks NonTrimmed; Pass N
recovers. Test now asserts Pass-1-only outcome (bytes_pending=total,
complete=false) consistent with the redesign.
Real-world impact on the user's BU40N + Dune Pt 2 trace from this
session: a damage zone that was on track to take ~40 minutes of
Pass-1 grinding will now jump in ~20 seconds. Pass N still has the
full 7-pass recovery budget to revisit those NonTrimmed ranges.
Two clippy issues surfaced when round 1 polish + round 2 FrameSink
migrations both landed on libfreemkv main:
- src/halt.rs: clippy::new_without_default fires when a public new()
exists without Default. The polish pass dropped the derive thinking
it was redundant — clippy disagrees, so add a manual impl that
forwards to new(). Doc-comment notes why both exist.
- src/disc/read_error.rs:372: pre-existing
assert_eq!(.., true) trips clippy::bool_assert_comparison. Pre-0.18
precommits passed because that lint sat outside the gate; the
round-2 commits brought enough new clippy surface that it now
shows up. Trivial cleanup: assert!(...) instead of assert_eq!.
Single contributor: MattJackson.
New disc/read_error.rs as the single entry point all read failures flow
through. Handler classifies the error, updates the in-flight context
(damage window, retry budgets, jump multiplier), and returns a
ReadAction the caller dispatches on. Pass 1 (sweep) refactored to use
it; ~340 lines of nested if/else collapsed into ~120 lines of action
dispatch. Adding a new error class = one match arm. Logging is in one
place. Bisect inner failures don't poison the damage window. Jump
multiplier capped at 64 (max 1 GB jump for batch=32 — observed prior
unbounded behavior produce a single 56 GB jump on a wedged drive).
Pass N (patch) damage_skip is now size-aware: each skip is capped at
range_remaining/4 rather than the absolute MB-scale escalation. The
old logic could leap over a 100-sector bad range that hides a 50-sector
good middle; size-aware convergence finds the good middles instead.
Tests in tests/pass_n_size_aware_skip.rs exercise the size-aware skip
against synthetic patterns (25-bad/50-good/25-bad and three good
middles in a row) and prove ≥98% of good middles are recovered.
Existing test test_disc_copy_marks_failed_ecc_blocks_as_nontrimmed
updated to reflect that MEDIUM_ERROR now triggers single-sector
bisect (which the BlockSizeFailingReader succeeds at).
Matthew Jackson