fluentdのread_from_headでログの欠損が治ったパターン ref: http://qiita.com/ikuwow/items/ea300af9d0ff2d90d69c

file0.txt

log-2016-02-01-00.log
log-2016-02-01-01.log
...
log-2016-02-01-22.log
log-2016-02-01-23.log
log-2016-02-02-00.log

file1.txt

<source>
  type tail
  path /path/to/log/log-%Y-%m-%d-%H.log
  ... 以下略
</source>

file2.txt

<source>
  type tail
  path /path/to/log/log-%Y-%m-%d-%H.log
  read_from_head true
  ... 以下略
</source>