OK, I've just solved problem with minor data lost. Steps to solve:
1) comment out FSEditLog.java:542 2) compile hadoop-core jar 3) start cluster with new jar Namenode will skip bad records in "name/current/edits" and write new edits file back into fs. As bad records stand for actual IO operations, some files in HDFS may be deleted as they consist of blocks which do not correspond to edits entries. In my situtation, I've lost files of last fortnight period. 4) wait for some time while datanodes are removing blocks, that do not corresond to entries in edits file 5) stop cluster 6) replace hadoop-core jar with release one 7) start cluster
