Informix Error -177

Reasons / Common Causes

-177 covers the second phase of a two-phase restore: after -176's physical restore brings back the archived data itself, logical restore replays logical log backups to bring the database forward to a consistent (or specifically targeted point-in-time) state. Same generic-wrapper principle as -173/-174/-176 — the accompanying SQL API error text carries the actual cause.

1. Missing or corrupted logical log backups needed to replay forward from the physical restore point — without a complete set, logical restore can't proceed.
2. A gap in the sequence of available logs — an incomplete set (even if individual logs are intact) prevents logical restore from reconstructing a consistent state.
3. A requested point-in-time target that isn't actually reachable given the available logs — specifying a recovery point beyond what the log backups on hand can replay to.
4. Network or media issues accessing the needed log backups, the same general class of cause as -173/-174/-176, specific to whichever logs this phase needs.

Solutions / Resolution

1. Check the accompanying SQL API error text first, exactly as with -173/-174/-176.
2. Verify all needed logical log backups are present, intact, and form a complete, gap-free sequence from the physical restore point forward to the desired recovery point.
3. If a specific point-in-time target was requested, confirm it's actually reachable given the available logs — adjust the target to what the available logs actually support if necessary.
4. Check network or media access to the log backups if they're stored remotely or on physical media.
5. Treat this with the same urgency as -176 — logical restore is part of an active disaster-recovery effort following a physical restore, not a routine maintenance operation.

Examples

Checking the associated error text first

-- As with -173/-174/-176, capture and read the accompanying SQL API
-- error text for the specific cause behind the generic -177 message

An unreachable point-in-time target

-- Physical restore completed from an archive taken Monday
-- Logical restore requested to recover to Wednesday 3pm
-- But log backups are only available through Tuesday
-- -177: the requested point-in-time target isn't reachable

Adjusting the recovery target to the latest point the available logs actually support (or locating the missing log backups, if they exist elsewhere) resolves this.

A gap in the log sequence

-- Available logs: 001, 002, 003, 005, 006
-- Log 004 is missing or corrupted
-- -177: logical restore can't replay past the gap at log 004

Diagnostic Checks

1. Capture and review the accompanying SQL API error text.
2. Inventory the available logical log backups and confirm they form a complete sequence from the physical restore point forward.
3. Confirm the requested recovery point is within what the available logs actually support.
4. Check network or media access to the log backups if remote or tape-based.

Related Errors / Related Topics

• -176 — "ISAM error: An error has occurred during physical restore." The first phase of the same two-phase restore process — logical restore (this error) only runs after physical restore succeeds.
• -173 — "ISAM error: An error has occurred during logical log back up." The source of the logs logical restore consumes — a gap or failure there is often the root cause of a subsequent -177.

Inventory the available logical log backups for completeness first — a gap or missing log in the sequence is a common, directly checkable cause of a failed logical restore.