index.merge.scheduler exception - java.io.IOException: Input/output error

[T Vinod Gupta]

Hi,
My log files are showing the below exceptions almost at twice a minute
frequency. what is causing it and how can i fix it? I am not using lucene
directly but instead using elasticsearch (0.18.7 version). but since the
stack trace is all lucene, i am sending it to this mailing list.

also, my queries are taking a long time to execute (sometimes take a
minute). could this be contributing to it somehow?

[2012-07-08 19:44:19,887][WARN ][index.merge.scheduler    ] [<my node
name>] [twitter][4] failed to merge
java.io.IOException: Input/output error:
NIOFSIndexInput(path="/media/ephemeral0
/ES_data/elasticsearch/nodes/0/indices/twitter/4/index/_2h29k.tis")
        at
org.apache.lucene.store.NIOFSDirectory$NIOFSIndexInput.readInternal(N
IOFSDirectory.java:180)
        at
org.apache.lucene.store.BufferedIndexInput.refill(BufferedIndexInput.
java:229)
        at
org.apache.lucene.store.BufferedIndexInput.readByte(BufferedIndexInput.java:39)
        at org.apache.lucene.store.DataInput.readVInt(DataInput.java:105)
        at
org.apache.lucene.store.BufferedIndexInput.readVInt(BufferedIndexInput.java:197)
        at org.apache.lucene.index.TermBuffer.read(TermBuffer.java:86)
        at
org.apache.lucene.index.SegmentTermEnum.next(SegmentTermEnum.java:133)
        at
org.apache.lucene.index.SegmentMergeInfo.next(SegmentMergeInfo.java:72)
        at
org.apache.lucene.index.SegmentMerger.mergeTermInfos(SegmentMerger.java:546)
        at
org.apache.lucene.index.SegmentMerger.mergeTerms(SegmentMerger.java:473)
        at
org.apache.lucene.index.SegmentMerger.merge(SegmentMerger.java:109)
        at
org.apache.lucene.index.IndexWriter.mergeMiddle(IndexWriter.java:4295)
        at org.apache.lucene.index.IndexWriter.merge(IndexWriter.java:3940)
        at
org.apache.lucene.index.ConcurrentMergeScheduler.doMerge(ConcurrentMergeScheduler.java:388)
        at
org.apache.lucene.index.TrackingConcurrentMergeScheduler.doMerge(TrackingConcurrentMergeScheduler.java:88)
        at
org.apache.lucene.index.ConcurrentMergeScheduler$MergeThread.run(ConcurrentMergeScheduler.java:456)
Caused by: java.io.IOException: Input/output error
        at sun.nio.ch.FileDispatcher.pread0(Native Method)
        at sun.nio.ch.FileDispatcher.pread(FileDispatcher.java:49)
        at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:248)
        at sun.nio.ch.IOUtil.read(IOUtil.java:224)
        at sun.nio.ch.FileChannelImpl.read(FileChannelImpl.java:663)
        at
org.apache.lucene.store.NIOFSDirectory$NIOFSIndexInput.readInternal(NIOFSDirectory.java:162)
        ... 15 more

thanks