You are viewing a plain text version of this content. The canonical link for it is here.
Posted to commits@cassandra.apache.org by "Stu Hood (JIRA)" <ji...@apache.org> on 2010/10/04 02:23:32 UTC

[jira] Created: (CASSANDRA-1569) New variant of NetworkTopologyStrategy to eliminate hotspots

New variant of NetworkTopologyStrategy to eliminate hotspots
------------------------------------------------------------

                 Key: CASSANDRA-1569
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1569
             Project: Cassandra
          Issue Type: Improvement
          Components: Core
            Reporter: Stu Hood
            Assignee: Stu Hood
             Fix For: 0.7.0


NetworkTopologyStrategy assigns replicas to the first endpoints encountered in the required DCs during a ring-order walk. This will lead to hotspots if you don't have an equal number of nodes in each DC, and if you don't alternate them in the ring.

An alternate algorithm that prevents hotspots is to choose replicas using fractions. If the first replica is on the 4th node of 10 for a particular DC, its fractional position is 0.4: remaining replicas in other DCs will be placed on the node at that fractional position.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.

[jira] Resolved: (CASSANDRA-1569) New variant of NetworkTopologyStrategy to eliminate hotspots

Posted by "Jonathan Ellis (JIRA)" <ji...@apache.org>.
     [ https://issues.apache.org/jira/browse/CASSANDRA-1569?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis resolved CASSANDRA-1569.
---------------------------------------

    Resolution: Fixed

Wouldn't it be simpler to just treat the different DCs as separate rings and bsearch each independently?

> New variant of NetworkTopologyStrategy to eliminate hotspots
> ------------------------------------------------------------
>
>                 Key: CASSANDRA-1569
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1569
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Stu Hood
>            Assignee: Stu Hood
>             Fix For: 0.7.0
>
>
> NetworkTopologyStrategy assigns replicas to the first endpoints encountered in the required DCs during a ring-order walk. This will lead to hotspots if you don't have an equal number of nodes in each DC, and if you don't alternate them in the ring.
> An alternate algorithm that prevents hotspots is to choose replicas using fractions. If the first replica is on the 4th node of 10 for a particular DC, its fractional position is 0.4: remaining replicas in other DCs will be placed on the node at that fractional position.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.

[jira] Updated: (CASSANDRA-1569) New variant of NetworkTopologyStrategy to eliminate hotspots

Posted by "Jonathan Ellis (JIRA)" <ji...@apache.org>.
     [ https://issues.apache.org/jira/browse/CASSANDRA-1569?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis updated CASSANDRA-1569:
--------------------------------------

    Affects Version/s: 0.7 beta 1

> New variant of NetworkTopologyStrategy to eliminate hotspots
> ------------------------------------------------------------
>
>                 Key: CASSANDRA-1569
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1569
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 0.7 beta 1
>            Reporter: Stu Hood
>            Assignee: Jonathan Ellis
>             Fix For: 0.7.0
>
>         Attachments: 1569.txt
>
>
> NetworkTopologyStrategy assigns replicas to the first endpoints encountered in the required DCs during a ring-order walk. This will lead to hotspots if you don't have an equal number of nodes in each DC, and if you don't alternate them in the ring.
> An alternate algorithm that prevents hotspots is to choose replicas using fractions. If the first replica is on the 4th node of 10 for a particular DC, its fractional position is 0.4: remaining replicas in other DCs will be placed on the node at that fractional position.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.

[jira] Updated: (CASSANDRA-1569) New variant of NetworkTopologyStrategy to eliminate hotspots

Posted by "Jonathan Ellis (JIRA)" <ji...@apache.org>.
     [ https://issues.apache.org/jira/browse/CASSANDRA-1569?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis updated CASSANDRA-1569:
--------------------------------------

    Attachment: 1569.txt

> New variant of NetworkTopologyStrategy to eliminate hotspots
> ------------------------------------------------------------
>
>                 Key: CASSANDRA-1569
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1569
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 0.7 beta 1
>            Reporter: Stu Hood
>            Assignee: Stu Hood
>             Fix For: 0.7.0
>
>         Attachments: 1569.txt
>
>
> NetworkTopologyStrategy assigns replicas to the first endpoints encountered in the required DCs during a ring-order walk. This will lead to hotspots if you don't have an equal number of nodes in each DC, and if you don't alternate them in the ring.
> An alternate algorithm that prevents hotspots is to choose replicas using fractions. If the first replica is on the 4th node of 10 for a particular DC, its fractional position is 0.4: remaining replicas in other DCs will be placed on the node at that fractional position.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.

[jira] Reopened: (CASSANDRA-1569) New variant of NetworkTopologyStrategy to eliminate hotspots

Posted by "Jonathan Ellis (JIRA)" <ji...@apache.org>.
     [ https://issues.apache.org/jira/browse/CASSANDRA-1569?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis reopened CASSANDRA-1569:
---------------------------------------


oops, didn't mean to Resolve w/ last comment.

... separate logical rings per DC is how NTS worked until r954657.  So that looks like a regression to me.

> New variant of NetworkTopologyStrategy to eliminate hotspots
> ------------------------------------------------------------
>
>                 Key: CASSANDRA-1569
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1569
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Stu Hood
>            Assignee: Stu Hood
>             Fix For: 0.7.0
>
>
> NetworkTopologyStrategy assigns replicas to the first endpoints encountered in the required DCs during a ring-order walk. This will lead to hotspots if you don't have an equal number of nodes in each DC, and if you don't alternate them in the ring.
> An alternate algorithm that prevents hotspots is to choose replicas using fractions. If the first replica is on the 4th node of 10 for a particular DC, its fractional position is 0.4: remaining replicas in other DCs will be placed on the node at that fractional position.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.