[
https://issues.apache.org/jira/browse/HDFS-3721?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13421751#comment-13421751
]
Todd Lipcon commented on HDFS-3721:
-----------------------------------
The issue here is the following code:
{code}
/** Header size for a packet */
private static final int PROTO_SIZE =
PacketHeaderProto.newBuilder()
.setOffsetInBlock(0)
.setSeqno(0)
.setLastPacketInBlock(false)
.setDataLen(0)
.setSyncBlock(false)
.build().getSerializedSize();
public static final int PKT_HEADER_LEN =
6 + PROTO_SIZE;
{code}
Since the new {{syncBlock}} flag is optional, this caused the packet header to
become variable-length depending on whether the client is post-hsync or not.
This screws up the datanode, resulting in an exception:
{code}
12/07/24 13:55:45 INFO datanode.DataNode: Exception in receiveBlock for
BP-2093170007-127.0.0.1-1342943513882:blk_3332306339985613438_1008
java.io.IOException: Data remaining in packet does not matchsum of checksumLen
and dataLen size remaining: 22 data len: 20 checksum Len: 4
at
org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receivePacket(BlockReceiver.java:595)
at
org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receivePacket(BlockReceiver.java:532)
at
org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receiveBlock(BlockReceiver.java:748)
{code}
> hsync support broke wire compatibility
> --------------------------------------
>
> Key: HDFS-3721
> URL: https://issues.apache.org/jira/browse/HDFS-3721
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: data-node, hdfs client
> Affects Versions: 2.1.0-alpha
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Critical
>
> HDFS-744 added support for hsync to the data transfer wire protocol. However,
> it actually broke wire compatibility: if the client has hsync support but the
> server does not, the client cannot write to the old cluster.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
