我是mongodb的新手，我的mongodb数据库有时会自动掉线。我找不到原因。我们还没有发出任何drop命令。但数据库丢失，日志文件包含，
MongoDB - 版本2.4.6
dropDatabase test starting
removeJournalFiles
dropDatabase test finished
Assertion: 13347:local.oplog.rs missing. did you drop it? if so restart server
0x9877f6 0x94bfaa 0x7998e8 0x794d8c 0x6b909e 0x6b95bc 0x7a1549 0x7a4b03 0x75a530 0x5a08eb 0x973c82 0x33b8e07f33 0x33b86f4ded
/usr/bin/mongod(_ZN5mongo15printStackTraceERSo+0x26) [0x9877f6]
/usr/bin/mongod(_ZN5mongo11msgassertedEiPKc+0x9a) [0x94bfaa]
/usr/bin/mongod() [0x7998e8]
/usr/bin/mongod(_ZN5mongo5logOpEPKcS1_RKNS_7BSONObjEPS2_Pbb+0x3c) [0x794d8c]
/usr/bin/mongod(_ZN5mongo7Command11execCommandEPS0_RNS_6ClientEiPKcRNS_7BSONObjERNS_14BSONObjBuilderEb+0xb6e) [0x6b909e]
/usr/bin/mongod(_ZN5mongo12_runCommandsEPKcRNS_7BSONObjERNS_11_BufBuilderINS_16TrivialAllocatorEEERNS_14BSONObjBuilderEbi+0x22c) [0x6b95bc]
/usr/bin/mongod(_ZN5mongo11runCommandsEPKcRNS_7BSONObjERNS_5CurOpERNS_11_BufBuilderINS_16TrivialAllocatorEEERNS_14BSONObjBuilderEbi+0x29) [0x7a1549]
/usr/bin/mongod(_ZN5mongo8runQueryERNS_7MessageERNS_12QueryMessageERNS_5CurOpES1_+0x6c3) [0x7a4b03]
/usr/bin/mongod(_ZN5mongo16assembleResponseERNS_7MessageERNS_10DbResponseERKNS_11HostAndPortE+0x6f0) [0x75a530]
/usr/bin/mongod(_ZN5mongo16MyMessageHandler7processERNS_7MessageEPNS_21AbstractMessagingPortEPNS_9LastErrorE+0xbb) [0x5a08eb]
/usr/bin/mongod(_ZN5mongo17PortMessageServer17handleIncomingMsgEPv+0x432) [0x973c82]
/lib64/libpthread.so.0() [0x33b8e07f33]
/lib64/libc.so.6(clone+0x6d) [0x33b86f4ded]
请有人向我解释自动数据库丢弃的原因。