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diff --git a/doc/v3compatibility.html b/doc/v3compatibility.html index b17aca82..c2a51139 100644 --- a/doc/v3compatibility.html +++ b/doc/v3compatibility.html @@ -87,7 +87,24 @@ via rsyslog.conf. That set of configuration directives is to be expanded. So far, we support:</p> <p>$klogSymbolsTwice [on/off]<br> $DebugPrintKernelSymbols [on/off] # spits *a lot* of messages at startup</p> -<h2>Queue Modes for the Main Message Queue</h2> +<h2>Output File Syncing</h2>Rsyslogd tries to keep as compatible to +stock syslogd as possible. As such, it retained stock syslogd's default +of syncing every file write if not specified otherwise (by placing a +dash in front of the output file name). While this was a useful feature +in past days where hardware was much less reliable and UPS seldom, this +no longer is useful in today's worl. Instead, the syncing is a high +performace hit. With it, rsyslogd writes files around 50 *times* slower +than without it. It also affects overall system performance due to the +high IO activity. In rsyslog v3, syncing has been turned off by +default. This is done via a specific configuration directive +"$ActionFileEnableSync on/off" which is off by default. So even if +rsyslogd finds sync selector lines, it ignores them by default. In +order to enable file syncing, the administrator must specify +"$ActionFileEnableSync on" at the top of rsyslog.conf. This ensures +that syncing only happens in those installations where the +administrator actually wanted that (performance-intense) feature. In +the fast majority of cases (if not all), this dramatically increases +rsyslogd performance without any negative effects.<h2>Queue Modes for the Main Message Queue</h2> <p>Either "FixedArray" or "LinkedList" is recommended. "Direct" is available, but should not be used except for a very good reason ("Direct" disables queueing and will potentially lead to message loss |