[
https://issues.apache.org/jira/browse/HDFS-1094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12886768#action_12886768
]
Tsz Wo (Nicholas), SZE commented on HDFS-1094:
----------------------------------------------
> Here the assumption is, correct me if it's wrong, that f nodes fail
> simultaneously. Otherwise, we should
> take into account replication process, ...
I totally agree that we should take account with replication process. That's
also the reason that we cannot ignore time T in the equations. A model only
consider data loss (i.e. disk failure) probability P without time T, in my
opinion, is not useful because simultaneous multiple disk failure probability
in real world is really low, probably negligible. I think it would happen only
in site-wise disaster situation.
Rodrigo, have you observed any case of simultaneous multiple disk failure?
> Intelligent block placement policy to decrease probability of block loss
> ------------------------------------------------------------------------
>
> Key: HDFS-1094
> URL: https://issues.apache.org/jira/browse/HDFS-1094
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: name-node
> Reporter: dhruba borthakur
> Assignee: Rodrigo Schmidt
> Attachments: prob.pdf, prob.pdf
>
>
> The current HDFS implementation specifies that the first replica is local and
> the other two replicas are on any two random nodes on a random remote rack.
> This means that if any three datanodes die together, then there is a
> non-trivial probability of losing at least one block in the cluster. This
> JIRA is to discuss if there is a better algorithm that can lower probability
> of losing a block.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
