Hi, I have 10 Node cluster running from last 25days( running with Hbase cluster). Recently observed that for every continuos blocks scans, there are many timeouts coming in DataNode. After this block scan verifications, again reads succeeded. This situation keep occurring many times now, for every continuous block scans. Here Hbase continuously performing many random reads.
Whether any one faced this situation in your clusters? Below is the logs with timeouts. 2011-12-28 11:30:42,618 INFO DataNode.clienttrace (BlockSender.java:sendBlock(529)) - src: /107.252.175.3:10010, dest: /107.252.175.3:52764, bytes: 264192, op: HDFS_READ, cliID: DFSClient_hb_rs_107-252-175-3,20020,1324837769603_1324837770095_1770885334_27, srvID: DS-306564179-107.252.175.3-10010-1322019943818, blockid: blk_1323251633953_187190 2011-12-28 11:30:42,621 INFO DataNode.clienttrace (BlockSender.java:sendBlock(529)) - src: /107.252.175.3:10010, dest: /107.252.175.3:52772, bytes: 396288, op: HDFS_READ, cliID: DFSClient_hb_rs_107-252-175-3,20020,1324837769603_1324837770095_1770885334_27, srvID: DS-306564179-107.252.175.3-10010-1322019943818, blockid: blk_1323251635735_188342 2011-12-28 11:30:42,641 INFO DataNode.clienttrace (BlockSender.java:sendBlock(529)) - src: /107.252.175.3:10010, dest: /107.252.175.3:52796, bytes: 396288, op: HDFS_READ, cliID: DFSClient_hb_rs_107-252-175-3,20020,1324837769603_1324837770095_1770885334_27, srvID: DS-306564179-107.252.175.3-10010-1322019943818, blockid: blk_1323251634096_187277 2011-12-28 11:30:42,889 INFO DataNode.clienttrace (BlockSender.java:sendBlock(529)) - src: /107.252.175.3:10010, dest: /107.252.175.3:52732, bytes: 264192, op: HDFS_READ, cliID: DFSClient_hb_rs_107-252-175-3,20020,1324837769603_1324837770095_1770885334_27, srvID: DS-306564179-107.252.175.3-10010-1322019943818, blockid: blk_1323251635763_188363 2011-12-28 11:30:42,889 INFO DataNode.clienttrace (BlockSender.java:sendBlock(529)) - src: /107.252.175.3:10010, dest: /107.252.175.3:52637, bytes: 264192, op: HDFS_READ, cliID: DFSClient_hb_rs_107-252-175-3,20020,1324837769603_1324837770095_1770885334_27, srvID: DS-306564179-107.252.175.3-10010-1322019943818, blockid: blk_1323251634921_187798 2011-12-28 11:30:42,976 INFO DataNode.clienttrace (BlockSender.java:sendBlock(529)) - src: /107.252.175.3:10010, dest: /107.252.175.3:52755, bytes: 396288, op: HDFS_READ, cliID: DFSClient_hb_rs_107-252-175-3,20020,1324837769603_1324837770095_1770885334_27, srvID: DS-306564179-107.252.175.3-10010-1322019943818, blockid: blk_1323251635359_188075 2011-12-28 11:30:57,757 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251602823_167208 2011-12-28 11:32:15,757 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251599175_166755 2011-12-28 11:32:54,561 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251673745_194676 2011-12-28 11:33:33,561 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251640709_189383 2011-12-28 11:34:12,557 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251649630_190779 2011-12-28 11:34:51,557 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251463964_91885 2011-12-28 11:35:23,958 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251636310_188845 2011-12-28 11:36:01,155 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1322486683238_54999 2011-12-28 11:36:04,157 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251678959_195786 2011-12-28 11:36:43,157 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251641803_189561 2011-12-28 11:37:20,357 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1322486706170_66445 2011-12-28 11:37:44,759 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251646924_190359 2011-12-28 11:38:23,759 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251673776_194683 2011-12-28 11:38:30,157 INFO datanode.DataBlockScanner (DataBlockScanner.java:verifyBlock(481)) - Verification succeeded for blk_1323251621379_178399 2011-12-28 11:38:37,549 INFO DataNode.clienttrace (BlockSender.java:sendBlock(529)) - src: /107.252.175.3:10010, dest: /107.252.175.3:51942, bytes: 396288, op: HDFS_READ, cliID: DFSClient_hb_rs_107-252-175-3,20020,1324837769603_1324837770095_1770885334_27, srvID: DS-306564179-107.252.175.3-10010-1322019943818, blockid: blk_1323251634345_187432 2011-12-28 11:38:37,550 WARN datanode.DataNode (DataXceiver.java:readBlock(274)) - DatanodeRegistration(107.252.175.3:10010, storageID=DS-306564179-107.252.175.3-10010-1322019943818, infoPort=10075, ipcPort=10020):Got exception while serving blk_1323251634345_187432 to /107.252.175.3: java.net.SocketTimeoutException: 480000 millis timeout while waiting for channel to be ready for write. ch : java.nio.channels.SocketChannel[connected local=/107.252.175.3:10010 remote=/107.252.175.3:51942] at org.apache.hadoop.net.SocketIOWithTimeout.waitForIO(SocketIOWithTimeout.java:249) at org.apache.hadoop.net.SocketOutputStream.waitForWritable(SocketOutputStream.java:159) at org.apache.hadoop.net.SocketOutputStream.transferToFully(SocketOutputStream.java:198) at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendChunks(BlockSender.java:410) at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendBlock(BlockSender.java:508) at org.apache.hadoop.hdfs.server.datanode.DataXceiver.readBlock(DataXceiver.java:247) at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:130) at java.lang.Thread.run(Thread.java:662) Regards, Uma