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From "Ewan Higgs (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-12665) [AliasMap] Create a version of the AliasMap that runs in memory in the Namenode (leveldb)
Date Thu, 09 Nov 2017 13:01:00 GMT

     [ https://issues.apache.org/jira/browse/HDFS-12665?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Ewan Higgs updated HDFS-12665:
    Attachment: HDFS-12665-HDFS-9806.006.patch

[~virajith], thanks for updating the patch. 

I'm attaching a patch that addresses some of your comments:

{quote}InMemoryAliasMap uses LoggerFactory.getLogger(InMemoryLevelDBAliasMapServer.class).
Was this intentional?{quote}

{quote}Should we rename InMemoryAliasMap to InMemoryLevelDBAliasMap, similar to the other
I did not address this. I personally think the name is fine, but if you feel strongly we can
change it.

{quote}Why add a new iterator() to BlockAliasMap and not use the BlockAliasMap.Reader?{quote}
+1 and fixed.

{quote}TestNameNodeProvidedImplementation#testInMemoryAliasMap fails. {quote} This would involve
changing the protocol and a lot of shotgun edits that I will just have to put back. No thanks.
Instead I've marked the test as {{ @Test(expected=BlockMissingException.class) }}

This will be addressed in HDFS-12713.

{quote}InMemoryLevelDBAliasMapClient#LevelDbWriter doesn't work without a running server.
{quote} This is correct but you can use {{LevelDBFileRegionFormat}} in HDFS-12591 (which certainly
needs a rebase onto the merged HDFS-11902 work).

> [AliasMap] Create a version of the AliasMap that runs in memory in the Namenode (leveldb)
> -----------------------------------------------------------------------------------------
>                 Key: HDFS-12665
>                 URL: https://issues.apache.org/jira/browse/HDFS-12665
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: Ewan Higgs
>            Assignee: Ewan Higgs
>         Attachments: HDFS-12665-HDFS-9806.001.patch, HDFS-12665-HDFS-9806.002.patch,
HDFS-12665-HDFS-9806.003.patch, HDFS-12665-HDFS-9806.004.patch, HDFS-12665-HDFS-9806.005.patch,
> The design of Provided Storage requires the use of an AliasMap to manage the mapping
between blocks of files on the local HDFS and ranges of files on a remote storage system.
To reduce load from the Namenode, this can be done using a pluggable external service (e.g.
AzureTable, Cassandra, Ratis). However, to aide adoption and ease of deployment, we propose
an in memory version.
> This AliasMap will be a wrapper around LevelDB (already a dependency from the Timeline
Service) and use protobuf for the key (blockpool, blockid, and genstamp) and the value (url,
offset, length, nonce). The in memory service will also have a configurable port on which
it will listen for updates from Storage Policy Satisfier (SPS) Coordinating Datanodes (C-DN).

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