Informix Error -311

Reasons / Common Causes

-311 is a serious, infrastructure-level error: the server can't even open one of its own system catalog tables (systables, syscolumns, and similar) for the current database — something well below the level of an ordinary application query going wrong. The official text points straight at the accompanying ISAM error code and any OS-level error messages as the real diagnostic path.

1. Filesystem or disk-level problems affecting the dbspace/chunk that holds the system catalog — a full disk, a permissions problem, a damaged or offline chunk.
2. Database corruption affecting the catalog tables specifically, from an unclean shutdown, hardware failure, or an interrupted operation.
3. Insufficient OS-level file permissions on the underlying chunk files for the Informix server process.
4. The database or an underlying dbspace is offline or in an inconsistent state, preventing normal catalog access.

Solutions / Resolution

1. Check the accompanying ISAM error code first, per the official guidance — it's the primary signal for what's actually failing underneath.
2. Check the online log and OS-level error messages for anything relevant occurring at the same time (disk I/O errors, permission denials, chunk status changes).
3. Verify the dbspace/chunk holding the database's system catalog is online (onstat -d) and not marked down or offline.
4. Check disk space and filesystem-level permissions on the underlying chunk files.
5. If corruption is suspected, engage standard DBA recovery procedures (consistency checks, restore from backup) rather than attempting to work around it at the application level — this isn't something a query rewrite can fix.

Examples

Checking chunk/dbspace status

onstat -d
-- look for the dbspace backing this database's system catalog;
-- confirm it isn't marked "D" (down) or otherwise offline

Checking the online log for related messages

onstat -m
-- or review $INFORMIXDIR/online.log directly for I/O errors,
-- permission denials, or chunk-status changes around the same time

Diagnostic Checks

1. Read the accompanying ISAM error code for the specific underlying condition.
2. Check onstat -d for the status of the dbspace/chunk holding the database's system catalog.
3. Review the online log / OS logs for I/O errors or permission problems at the same timestamp.
4. Check available disk space on the filesystem(s) backing the relevant chunks.

Related Errors / Related Topics

• -310 — "Table table-name already exists in database." A much more routine table-naming condition — useful contrast, since -311 is an infrastructure-level failure rather than an ordinary application-level mistake.
• -296 — "Referenced table table-name not available." Another table-access failure, though at the level of an individual application table rather than the system catalog itself.

This is a server/infrastructure-level failure, not a query-writing mistake — the ISAM error code and the online log are the real diagnostic starting points, not the SQL statement itself.