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https://issues.apache.org/jira/browse/HDFS-8341?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14538625#comment-14538625
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Tsz Wo Nicholas Sze commented on HDFS-8341:
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> ... If replica scheduled successfully it will return, but here it should
> continue for next replica.
The reason of returning is that we don't want to move multiple replicas of the
same block at once.
> Now the problem is, if file have more than one block for example 10 ...
Do you mean "a block has more than one replicas for example 10"?
> ... and some problem in moving first replica then scheduleMoves4Block() API
> will always schedule first replica in each iteration and it will return.
The locations are shuffled so that the first replica is not necessarily the
same in each iteration. Am I missing anything?
{code}
//scheduleMoves4Block
Collections.shuffle(locations);
{code}
> HDFS mover stuck in loop after failing to move block, doesn't move rest of
> blocks, can't get data back off decommissioning external storage tier as a
> result
> ------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-8341
> URL: https://issues.apache.org/jira/browse/HDFS-8341
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: balancer & mover
> Affects Versions: 2.6.0
> Environment: HDP 2.2
> Reporter: Hari Sekhon
> Assignee: surendra singh lilhore
> Priority: Blocker
>
> HDFS mover gets stuck looping on a block that fails to move and doesn't
> migrate the rest of the blocks.
> This is preventing recovery of data from a decomissioning external storage
> tier used for archive (we've had problems with that proprietary "hyperscale"
> storage product which is why a couple blocks here and there have checksum
> problems or premature eof as shown below), but this should not prevent moving
> all the other blocks to recover our data:
> {code}hdfs mover -p /apps/hive/warehouse/<custom_scrubbed>
> 15/05/07 14:52:50 INFO mover.Mover: namenodes =
> {hdfs://nameservice1=[/apps/hive/warehouse/<custom_scrubbed>]}
> 15/05/07 14:52:51 INFO balancer.KeyManager: Block token params received from
> NN: update interval=10hrs, 0sec, token lifetime=10hrs, 0sec
> 15/05/07 14:52:51 INFO block.BlockTokenSecretManager: Setting block keys
> 15/05/07 14:52:51 INFO balancer.KeyManager: Update block keys every 2hrs,
> 30mins, 0sec
> 15/05/07 14:52:52 INFO block.BlockTokenSecretManager: Setting block keys
> 15/05/07 14:52:52 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:52:52 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:52:52 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:52:52 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:52:52 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:52:52 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:52:52 WARN balancer.Dispatcher: Failed to move
> blk_1075156654_1438349 with size=134217728 from <ip>:1019:ARCHIVE to
> <ip>:1019:DISK through <ip>:1019: block move is failed: opReplaceBlock
> BP-120244285-<ip>-1417023863606:blk_1075156654_1438349 received exception
> java.io.EOFException: Premature EOF: no length prefix available
> <NOW IT STARTS LOOPING ON SAME BLOCK>
> 15/05/07 14:53:31 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:53:31 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:53:31 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:53:31 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:53:31 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:53:31 INFO net.NetworkTopology: Adding a new node:
> /default-rack/<ip>:1019
> 15/05/07 14:53:31 WARN balancer.Dispatcher: Failed to move
> blk_1075156654_1438349 with size=134217728 from <ip>:1019:ARCHIVE to
> <ip>:1019:DISK through <ip>:1019: block move is failed: opReplaceBlock
> BP-120244285-<ip>-1417023863606:blk_1075156654_1438349 received exception
> java.io.EOFException: Premature EOF: no length prefix available
> ...<repeat indefinitely>...
> {code}
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