Informix Error -183: ISAM error: DDR log post processing is already active.

Reasons / Common Causes

-183 is a double-start condition: something attempted to start DDR (Dynamic Data Replication) log post-processing while it was already running. The official text frames this as an internal error, but the practical trigger is almost always a redundant start attempt rather than anything actually broken.

1. An administrative command or automated process attempting to start DDR log post-processing while it's already active — the direct cause.
2. A monitoring or automation script that doesn't check current status before issuing a start command — a retry mechanism or a scheduling overlap can trigger this if the script assumes it needs to (re)start something that's already running.
3. Multiple administrators or automated jobs independently attempting to start replication- related processing around the same time, without coordination.
4. A prior start command that appeared to fail or didn't confirm success clearly, prompting a retry, when in fact it had already succeeded and was running.

Solutions / Resolution

1. Check current DDR log post-processing status before attempting to start it.
2. If it's already active and running as intended, no action is needed. This error is the system enforcing that a duplicate start doesn't happen — it isn't itself causing any problem.
3. For automation or scripts, add a status check before issuing a start command, and treat "already active" as a success condition rather than a failure to retry against.
4. Coordinate any administrators or automated jobs that might independently attempt to start this process, to avoid redundant attempts going forward.

Examples

Treating "already active" as success in automation

-- Before: a script unconditionally issues a start command
start_ddr_postprocessing()

-- After: check status first
if not ddr_postprocessing_active():
    start_ddr_postprocessing()
else:
    log("DDR post-processing already active — no action needed")

Diagnostic Checks

1. Check DDR/replication status directly to confirm it's genuinely already running.
2. Review recent start-command history for an accidental duplicate attempt, whether manual or automated.

Related Errors / Related Topics

• -185 — "ISAM error: DDR log post processing is not active." The direct opposite condition — worth knowing together as the two ends of the same status check.
• -100 — "ISAM error: duplicate value for a record with unique key." The other foundational ISAM-level error in this family, unrelated in cause.

Check status before assuming anything is wrong — this error usually means the thing being started is already running correctly.