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.
matthew
231b9d2cb1