[jira] Issue Comment Edited: (CASSANDRA-279) finish snapshot support

["Michael Greene (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12732798#action_12732798 ] 

Michael Greene edited comment on CASSANDRA-279 at 7/17/09 5:21 PM:
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This won't apply to trunk.  Can you rebase?

Shouldn't snapshot directories be a list since it mirrors data file directories?
Is there no way to expose the tag parameter to nodeprobe?  Also, if the output stream isn't going to be used it should probably not be passed to takeSnapshot.

      was (Author: euphoria):
    This won't apply to trunk.  Can you rebase?
  
> finish snapshot support
> -----------------------
>
>                 Key: CASSANDRA-279
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-279
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Sammy Yu
>         Attachments: 0001-Work-for-CASSANDRA-279.patch, 0001-Work-for-CASSANDRA-279.patch, 0002-Work-for-CASSANDRA-279.patch
>
>
> searching for "snapshot" in *.java shows a bunch of code for supporting snapshots via hard links.
> (this works b/c SSTables are immutable, once created.)
> this used to be more complete but when we dropped the JDK7 requirement we just removed the code that we couldn't do in JDK6 and hard link support was one of those.
> So what you would need to do here is:
>  * create a hard link method (using Runtime.exec("ln") on linux / os x I imagine)
>  * add a JMX hook to invoke this on the data files (this is where looking at the old codebase might help); ColumnFamilyStoreMBean.forceFlush is an example of an "Action" jmx interface. using jconsole to interact with JMX stuff is explained here: http://wiki.apache.org/cassandra/MemtableThresholds
>  * add something to list the snapshots available via JMX
>  * optionally make this all per-Table instead of per-database

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