When using tar to backup some files, you may face such errors sometime, it's caused by an type of "internal" file error, that means your file system may need a fsck check.

[joseph@bj-592 data]$ ls -l /data/30/056/082/42397DF6446555
-rw-r--r-- 1 datum root 8990605 Oct 21 02:50 /data/30/056/082/42397DF6446555
[joseph@bj-592 data]$ du -sh /data/30/056/082/42397DF6446555
8.6M /data/30/056/082/42397DF6446555
[joseph@bj-592 data]$ wc -l /data/30/056/082/42397DF6446555 1>/dev/null
wc: /data/30/056/082/42397DF6446555: Input/output error

From the command above, you'd see the real cause.

ERROR OUTPUT FROM COMMAND LINE EXAMPLES:
tar: /data/30/056/006/42397DFD3CA255: File shrank by 4909337 bytes; padding with zeros
tar: /data/30/056/006/42397DFEF37255: File shrank by 543683 bytes; padding with zeros
tar: /data/30/056/006/42397E02241D55: File shrank by 2461249 bytes; padding with zeros
tar: /data/30/056/006/42397E02326A55: File shrank by 8030 bytes; padding with zeros
tar: /data/30/056/012/42397DFECDA955: File shrank by 2026228 bytes; padding with zeros
tar: /data/30/056/012/42397DFF79F255: File shrank by 37629 bytes; padding with zeros
tar: /data/30/056/017/42397DFC703F55: File shrank by 114590 bytes; padding with zeros
tar: /data/30/056/017/42397DFD12C255: File shrank by 573544 bytes; padding with zeros
tar: /data/30/056/017/42397E004F2C55: File shrank by 36199 bytes; padding with zeros