Mailing-List: contact notifications-help@accumulo.apache.org; run by ezmlm
Precedence: bulk
Reply-To: jira@apache.org
Date: Wed, 2 Mar 2016 22:07:18 +0000 (UTC)
From: "Josh Elser (JIRA)" <jira@apache.org>
To: notifications@accumulo.apache.org
Message-ID: <JIRA.12946256.1456945550000.200299.1456956438088@Atlassian.JIRA>
In-Reply-To: <JIRA.12946256.1456945550000@Atlassian.JIRA>
References: <JIRA.12946256.1456945550000@Atlassian.JIRA>
 <JIRA.12946256.1456945550332@arcas>
Subject: [jira] [Commented] (ACCUMULO-4156) Tunable replication frequency
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/ACCUMULO-4156?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15176574#comment-15176574 ] 

Josh Elser commented on ACCUMULO-4156:
--------------------------------------

To expand some more (for my own benefit): I was initially considering using offset into WAL entries as the tracking point, however, it might be more consistent to use the same last compaction after the last start (same logic wal recovery uses). I'm not sure if we need to do that for the same consistency reasons that WAL does, but it might be a little more natural (the flow inside the tabletserver is already set up to record the flushID) than just offset tracking into the WALs .

> Tunable replication frequency
> -----------------------------
>
>                 Key: ACCUMULO-4156
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4156
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.7.1
>            Reporter: William Slacum
>             Fix For: 1.8.0
>
>
> Currently, replication happens when a write ahead log file is closed. The only parameter to toggle when this event occurs is write ahead log size, and is only applicable to the tablet servers themselves.
> By default this means that when replication happens isn't tied to the table it is configured on, but also exogenous factors such as total write load and failures. If a system receives ~100MB/day/TServer, and the WAL size is its default 1GB, it will take 10 days for any replication event to occur. Another possibility is that an unreplicated table is receiving many writes, which will cause more frequent replication events, but proportionally the work will involve less data for the table being replicated.
> I don't have a specific implementation in mind, but I'd like to see a solution that involves isolating the work down to specific table events such as time-since-last-replication and data-added-since-last-replication.
> [~elserj] has had some ideas about doing things incrementally within WAL files (ie, replicating between two sync points) that can also help with this. 


--
This message was sent by Atlassian JIRA
(v6.3.4#6332)