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<chapter id="wal">

<title>Reliability and the Write-Ahead Log</title>

command forces all data from the BBU to the disks, eliminating much

of the benefit of the BBU. You can run the utility

<filename>src/tools/fsync</> in the PostgreSQL source tree to see

if you areeffected. If you areeffected, the performance benefits

if you areaffected. If you areaffected, the performance benefits

of the BBU cache can be regained by turning off write barriers in

the file system or reconfiguring the disk controller, if that is

an option. If write barriers are turned off, make sure the battery