just found the data dir consume a lot of space, which is because there was many snapshots in it.
but I have set snapshot_before_compaction: false. is that possible that cassandra create those snapshot automatically? could I delete them? the dir names is strange(normally it should contain date info like this one: 1309954201568-20110706snap): 1309954201568-20110706snap 1313655860450 1313657278693 1313658563469 1313660368230 1313661946829 1313673041895 1313978414627 1313993893774 1313994151125 1309954218127-20110706snap 1313655977397 1313657539385 1313658794663 1313660540216 1313665575966 1313684621571 1313981129181 1313993899685 1313994436489 1309954367559-20110706snap 1313656318839 1313657769222 1313659117385 1313660791414 1313670545340 1313688842151 1313993527645 1313994045681 1313994537282 1313655524690 1313656750454 1313657987723 1313659841880 1313661186615 1313671377867 1313821800047 1313993601281 1313994093703 1313994548470 1313655632823 1313657058205 1313658288595 1313660165346 1313661433088 1313672861562 1313822718672 1313993882415 1313994138019 1313994791621