> [!WALCopySync] > <table><tr><td rowspan="4" width="25%"><img src="assets/wl_io_walcopysync.png"></td><td><b>Wait Category</b></td><td>IO</td></tr><tr><td><b>Mechanism</b></td><td><code>pg_wal</code></td></tr><tr><td><b>Operations</b></td><td><a href="Operations/Distributed/Redistribute">Redistribute</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>Log Management Durability Barrier</b>. Before a recycled WAL segment can be safely used for new transaction data, the engine must ensure that the previous copy operation (and any zeroing) has reached the physical media.</td></tr></table>