Normally I dislike writing about problems without being able to provide some more information, but unfortunately in this case I just can't find anything.
Here is the situation - DFS cluster running Hadoop version 0.19.0. The cluster is running on multiple servers with practically identical hardware. Everything works perfectly well, except for one thing - from time to time one of the data nodes (every time it's a different node) starts to consume more and more disk space. The node keeps going and if we don't do anything - it runs out of space completely (ignoring 20GB reserved space settings). Once restarted - it cleans disk rapidly and goes back to approximately the same utilization as the rest of data nodes in the cluster. Scanning datanodes and namenode logs and comparing thread dumps (stacks) from nodes experiencing problem and those that run normally didn't produce any clues. Running balancer tool didn't help at all. FSCK shows that everything is healthy and number of over-replicated blocks is not significant. To me - it just looks like at some point the data node stops cleaning invalidated/deleted blocks, but keeps reporting space consumed by these blocks as "not used", but I'm not familiar enough with the internals and just plain don't have enough free time to start digging deeper. Anyone has an idea what is wrong or what else we can do to find out what's wrong or maybe where to start looking in the code? Thanks, Igor
