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https://issues.apache.org/jira/browse/BOOKKEEPER-592?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13645260#comment-13645260
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Sijie Guo commented on BOOKKEEPER-592:
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{code}
We would need to keep that information with the metadata and use it to drive
the selection when replacing bookies.
{code}
why we need to keep information with metadata? should IP address be enough for
selection? putting information with metadata, you had to consider metadata
update, backward compatibility issue?
my thought is to have an EnsembleSelectionPolicy interface, which has an method
#newEnsemble(Set<InetSocketAddress> knownBookies, int ensembleSize).
have a method in BookKeeper #setEnsembleSelectionPolicy().
by default, we provide a random selection policy. and user could implement its
selection policy based on rack information or other application properties. how
does it sound?
> allow application to recommend ledger data locality
> ---------------------------------------------------
>
> Key: BOOKKEEPER-592
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-592
> Project: Bookkeeper
> Issue Type: Improvement
> Reporter: Ming Ma
> Assignee: Sijie Guo
>
> For application like hbase WAL, it will be useful if application like hbase
> can give a hint to bk about application's preferred ledger location. In that
> way, application can fail over to specific machines where one of the ledger
> replica is located; the recovery time will be faster. Another scenario is
> hbase's support for hot standby region server where read request can be
> served from a different machine other than the active region server. That
> requires the hot standby region server to read from ledger. If the ledger is
> on the same machine as standby region server, the performance will be better.
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