> [!SLRUSync] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_io_slrusync.png"></td><td><b>Wait Category</b></td><td>IO</td></tr><tr><td><b>Mechanism</b></td><td><code>SLRU</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Tuple/ModifyTable">ModifyTable</a></td></tr><tr><td><b>Resources</b></td><td><a href="Resources/disk IO">disk IO</a>, <a href="Resources/CPU">CPU</a></td></tr><tr><td colspan="3"><b>Transaction-Level Metadata Durability Barrier</b>. Before a transaction can be considered "finished" (especially if it involves Subtransactions or MultiXacts), the metadata describing its status must be safe on disk.</td></tr></table>