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From "Aaron T. Myers (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-2602) NN should log newly-allocated blocks without losing BlockInfo
Date Thu, 15 Dec 2011 19:30:33 GMT

     [ https://issues.apache.org/jira/browse/HDFS-2602?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Aaron T. Myers updated HDFS-2602:
---------------------------------

    Description: 
Without the patch in HDFS-1108, new block allocations aren't logged to the edits log. For
HA, we'll need that functionality and we'll need to make sure that block locations aren't
blown away in the Standby NN when tailing the edits log.

As described in HDFS-1975:

When we close a file, or add another block to a file, we write OP_CLOSE or OP_ADD in the txn
log. FSEditLogLoader, when it sees these types of transactions, creates new BlockInfo objects
for all of the blocks listed in the transaction. These new BlockInfos have no block locations
associated. So, when we close a file, the SBNN loses its block locations info for that file
and is no longer "hot".

I have an ugly hack which copies over the old BlockInfos from the existing INode, but I'm
not convinced it's the right way. It might be cleaner to add new opcode types like OP_ADD_ADDITIONAL_BLOCK,
and actually treat OP_CLOSE as just a finalization of INodeFileUnderConstruction to INodeFile,
rather than replacing block info at all.

  was:
As described in HDFS-1975:

When we close a file, or add another block to a file, we write OP_CLOSE or OP_ADD in the txn
log. FSEditLogLoader, when it sees these types of transactions, creates new BlockInfo objects
for all of the blocks listed in the transaction. These new BlockInfos have no block locations
associated. So, when we close a file, the SBNN loses its block locations info for that file
and is no longer "hot".

I have an ugly hack which copies over the old BlockInfos from the existing INode, but I'm
not convinced it's the right way. It might be cleaner to add new opcode types like OP_ADD_ADDITIONAL_BLOCK,
and actually treat OP_CLOSE as just a finalization of INodeFileUnderConstruction to INodeFile,
rather than replacing block info at all.

        Summary: NN should log newly-allocated blocks without losing BlockInfo  (was: Standby
needs to maintain BlockInfo while following edits)
    
> NN should log newly-allocated blocks without losing BlockInfo
> -------------------------------------------------------------
>
>                 Key: HDFS-2602
>                 URL: https://issues.apache.org/jira/browse/HDFS-2602
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: ha
>    Affects Versions: HA branch (HDFS-1623)
>            Reporter: Todd Lipcon
>            Assignee: Aaron T. Myers
>            Priority: Critical
>         Attachments: HDFS-2602.patch, HDFS-2602.patch, HDFS-2602.patch
>
>
> Without the patch in HDFS-1108, new block allocations aren't logged to the edits log.
For HA, we'll need that functionality and we'll need to make sure that block locations aren't
blown away in the Standby NN when tailing the edits log.
> As described in HDFS-1975:
> When we close a file, or add another block to a file, we write OP_CLOSE or OP_ADD in
the txn log. FSEditLogLoader, when it sees these types of transactions, creates new BlockInfo
objects for all of the blocks listed in the transaction. These new BlockInfos have no block
locations associated. So, when we close a file, the SBNN loses its block locations info for
that file and is no longer "hot".
> I have an ugly hack which copies over the old BlockInfos from the existing INode, but
I'm not convinced it's the right way. It might be cleaner to add new opcode types like OP_ADD_ADDITIONAL_BLOCK,
and actually treat OP_CLOSE as just a finalization of INodeFileUnderConstruction to INodeFile,
rather than replacing block info at all.

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