Informix Error -21531: Defragment: A partition that contains a partition header page table cannot be defragmented.

Reasons / Common Causes

-21531 fires when defragmentation targets a partition containing a partition header page table — per the official guidance, this isn't allowed.

1. The target partition containing a partition header page table, per the official guidance — the direct, only cause.

Solutions / Resolution

1. Don't run the defragmenter on a partition header page table, per the official guidance — this operation is disallowed outright.

Examples

N/A

No specific triggering statement is documented beyond targeting a partition header page table for defragmentation.

Diagnostic Checks

1. Check whether the target partition contains a partition header page table, and choose a different, eligible partition.

Related Errors / Related Topics

• -21532 — "Defragment: The partition is in the wrong state or an incompatible type." A related defragmentation-eligibility restriction, general to unsupported partition states/types rather than specifically partition header page tables.

Defragmentation was attempted on a partition header page table, which isn't allowed — choose a different, eligible partition.