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Posted to commits@cassandra.apache.org by "Yang Yang (JIRA)" <ji...@apache.org> on 2011/02/10 02:53:57 UTC

[jira] Commented: (CASSANDRA-1872) Provide ability send notifications via JMX when an SSTable is written

    [ https://issues.apache.org/jira/browse/CASSANDRA-1872?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12992833#comment-12992833 ] 

Yang Yang commented on CASSANDRA-1872:
--------------------------------------

sorry guys I didn't get any email triggers for comments here, so have been late in reply.



the notification missing is indeed possible. but it's practically impossible if you setup the listener on the same host as cassandra/JMX server.

in the rare event that data is lost, we do use this in conjunction with complete snapshot backup, so we could just cut a new, clean snapshot, and add the incrementals from there on. 


to automatically verify the validity of the incrementals, something more needs to be worked out, for example, keeping a persistent, monotonically increasing sequence number for all the SSTables. but that's probably an overkill for the slight danger of missing one. 

crawling the FS was indeed one of our original thoughts, but here you face the issue that you could lose the fresh level-0 SStables after they are compacted, before the crawling operation is executed periodically. also you could face a change in the physical dir layout.  


Thanks 
Yang

> Provide ability send notifications via JMX when an SSTable is written
> ---------------------------------------------------------------------
>
>                 Key: CASSANDRA-1872
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1872
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Tools
>            Reporter: Nate McCall
>         Attachments: full.diff, jmockit-0.999.5.jar
>
>
> One application of interest is the immediate backup of new SSTables. Relying on JMX's MBeanNotificationInfo would be a minimally intrusive to add "listeners" to CFS to facilitate this. 

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