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https://issues.apache.org/activemq/browse/AMQ-2837?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=60822#action_60822
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Gary Tully commented on AMQ-2837:
---------------------------------

There is a utility in the distribution that can help you determine relative 
disk speed as experienced by the journal writer thread:

java -classpath lib/kahadb-<version>.jar org.apache.kahadb.util.DiskBenchmark 

As to the value of the log threshold, the calculation is a simple time 
difference before and after the journal and index update, there is no 
complicated formula and it really is there as a development aid. So pick a 
large value if you have a slow disk and don't want to see the log entry. 
Otherwise you will be regularly reminded of the fact.

> Slow KahaDB
> -----------
>
>                 Key: AMQ-2837
>                 URL: https://issues.apache.org/activemq/browse/AMQ-2837
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 5.3.2
>         Environment: Linux
>            Reporter: Andy
>            Assignee: Rob Davies
>
> I'm using KahaDB for persistence with the following configuration:
> <?xml version="1.0" encoding="UTF-8"?>
> <beans>
>   <broker brokerName="test-broker"
>         persistent="true"
>         useJmx="true" 
>         useShutdownHook="false"
>         deleteAllMessagesOnStartup="false"
>         xmlns="http://activemq.apache.org/schema/core";>
>     <persistenceAdapter>
>       <kahaDB directory="activemq-data" journalMaxFileLength="32mb" 
> indexCacheSize="10000000
> "/>
>     </persistenceAdapter>
>     <transportConnectors>
>       <transportConnector uri="tcp://localhost:61616"/>
>     </transportConnectors>
>     <destinationPolicy>
>       <policyMap>
>       <policyEntries>
>         <policyEntry topic=">">
>           <subscriptionRecoveryPolicy>
>             <timedSubscriptionRecoveryPolicy recoverDuration="3600000"/>
>           </subscriptionRecoveryPolicy>
>         </policyEntry>
>       </policyEntries>
>       </policyMap>
>     </destinationPolicy>
> </broker>
> </beans>
> I've some durable consumers. The broker is showing many "Slow KahaDB access" 
> log entries. 
> Any suggestions?
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1248 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1560 
> ms
>  INFO | Slow KahaDB access: Journal append took: 1 ms, Index update took 1227 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1227 
> ms
>  INFO | Slow KahaDB access: Journal append took: 1480 ms, Index update took 0 
> ms
>  INFO | Slow KahaDB access: Journal append took: 5 ms, Index update took 1302 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1302 
> ms
>  INFO | Slow KahaDB access: Journal append took: 13 ms, Index update took 
> 1348 ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1590 
> ms
>  INFO | Slow KahaDB access: Journal append took: 1327 ms, Index update took 0 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1263 
> ms
>  INFO | Slow KahaDB access: Journal append took: 1 ms, Index update took 1276 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1277 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1318 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1312 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1593 
> ms
>  INFO | Slow KahaDB access: Journal append took: 3 ms, Index update took 1608 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1302 
> ms
>  INFO | Slow KahaDB access: Journal append took: 3 ms, Index update took 1317 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1318 
> ms
>  INFO | Slow KahaDB access: Journal append took: 2 ms, Index update took 1316 
> ms
>  INFO | Slow KahaDB access: Journal append took: 1318 ms, Index update took 1 
> ms
>  INFO | Slow KahaDB access: Journal append took: 0 ms, Index update took 1296 
> ms

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