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3 | 3 | <chapter id="wal"> |
4 | 4 | <title>Reliability and the Write-Ahead Log</title> |
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139 | 139 | <para> |
140 | 140 | Because <acronym>WAL</acronym> restores database file |
141 | 141 | contents after a crash, it is not necessary to use a |
142 | | - journaled filesystem; infact, journaling overhead can |
143 | | -reduce performance. For bestperformance,turn off |
144 | | - <emphasis>data</emphasis>journaling as a filesystem mount |
145 | | -option, e.g. use <literal>data=writeback</> on Linux. |
146 | | -Meta-data journaling (e.g. file creation and directory |
147 | | -modification) is still desirable for faster rebooting after |
148 | | - a crash. |
| 142 | + journaled filesystem for reliability. Infact, journaling |
| 143 | +overhead can reduceperformance,especially if journaling |
| 144 | +causes file system<emphasis>data</emphasis>to be flushed |
| 145 | +to disk. Fortunately,data flushing during journaling can |
| 146 | +often be disabled with a filesystem mount option, e.g. |
| 147 | +<literal>data=writeback</> on a Linux ext3 file system. |
| 148 | +Journaled file systems do improve boot speed aftera crash. |
149 | 149 | </para> |
150 | 150 | </tip> |
151 | 151 |
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