Mongodb 无法在debian上初始化副本集（在createPrivateMap中打开/创建失败）

我尝试在运行Debian 7.3的新虚拟服务器上安装MongoDB。如果尝试使用配置副本集

hosts = {
   "_id" : "rs0",
   "version" : 1,
   "members" : [
      {
         "_id" : 0,
         "host" : "localhost:27017"
      }
   ]
}

rs.initiate(hosts);

MongoDB崩溃，但出现以下异常：

Tue Jan 21 00:10:24.599 [initandlisten] MongoDB starting : pid=3616 port=27017 dbpath=/var/lib/mongodb 64-bit host=lvps176-28-17-95.dedicated.hosteurope.de
Tue Jan 21 00:10:24.599 [initandlisten]
Tue Jan 21 00:10:24.600 [initandlisten] ** WARNING: You are running in OpenVZ. This is known to be broken!!!
Tue Jan 21 00:10:24.600 [initandlisten]
Tue Jan 21 00:10:24.600 [initandlisten] db version v2.4.7
Tue Jan 21 00:10:24.600 [initandlisten] git version: 0161738abf06c1f067b56a465b706efd6f4bf2aa
Tue Jan 21 00:10:24.600 [initandlisten] build info: Linux ip-10-2-29-40 2.6.21.7-2.ec2.v1.2.fc8xen #1 SMP Fri Nov 20 17:48:28 EST 2009 x86_64 BOOST_LIB_VERSION=1_49
Tue Jan 21 00:10:24.600 [initandlisten] allocator: tcmalloc
Tue Jan 21 00:10:24.600 [initandlisten] options: { config: "/etc/mongodb.conf", dbpath: "/var/lib/mongodb", logappend: "true", logpath: "/var/log/mongodb/mongodb.log", replSet: "rs0" }
Tue Jan 21 00:10:24.609 [initandlisten] journal dir=/var/lib/mongodb/journal
Tue Jan 21 00:10:24.609 [initandlisten] recover : no journal files present, no recovery needed
Tue Jan 21 00:10:24.740 [initandlisten] preallocateIsFaster=true 2.38
Tue Jan 21 00:10:24.780 [initandlisten] waiting for connections on port 27017
Tue Jan 21 00:10:24.780 [websvr] admin web console waiting for connections on port 28017
Tue Jan 21 00:10:24.786 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)
Tue Jan 21 00:10:24.786 [rsStart] replSet info you may need to run replSetInitiate -- rs.initiate() in the shell -- if that is not already done
Tue Jan 21 00:10:27.429 [initandlisten] connection accepted from 127.0.0.1:50602 #1 (1 connection now open)
Tue Jan 21 00:10:34.786 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)
Tue Jan 21 00:10:40.160 [conn1] replSet replSetInitiate admin command received from client
Tue Jan 21 00:10:40.163 [conn1] replSet replSetInitiate config object parses ok, 1 members specified
Tue Jan 21 00:10:40.164 [conn1] replSet replSetInitiate all members seem up
Tue Jan 21 00:10:40.164 [conn1] ******
Tue Jan 21 00:10:40.164 [conn1] creating replication oplog of size: 24630MB...

Tue Jan 21 00:10:40.165 [FileAllocator] allocating new datafile /var/lib/mongodb/local.1, filling with zeroes...
Tue Jan 21 00:10:40.165 [FileAllocator] creating directory /var/lib/mongodb/_tmp
Tue Jan 21 00:10:40.205 [FileAllocator] done allocating datafile /var/lib/mongodb/local.1, size: 2047MB,  took 0.036 secs
Tue Jan 21 00:10:40.206 [FileAllocator] allocating new datafile /var/lib/mongodb/local.2, filling with zeroes...
Tue Jan 21 00:10:40.233 [FileAllocator] done allocating datafile /var/lib/mongodb/local.2, size: 2047MB,  took 0.027 secs
Tue Jan 21 00:10:40.234 [FileAllocator] allocating new datafile /var/lib/mongodb/local.3, filling with zeroes...
Tue Jan 21 00:10:40.255 [FileAllocator] done allocating datafile /var/lib/mongodb/local.3, size: 2047MB,  took 0.02 secs
Tue Jan 21 00:10:40.256 [FileAllocator] allocating new datafile /var/lib/mongodb/local.4, filling with zeroes...
Tue Jan 21 00:10:40.275 [FileAllocator] done allocating datafile /var/lib/mongodb/local.4, size: 2047MB,  took 0.019 secs
Tue Jan 21 00:10:40.276 [FileAllocator] allocating new datafile /var/lib/mongodb/local.5, filling with zeroes...
Tue Jan 21 00:10:40.355 [FileAllocator] done allocating datafile /var/lib/mongodb/local.5, size: 2047MB,  took 0.079 secs
Tue Jan 21 00:10:40.356 [FileAllocator] allocating new datafile /var/lib/mongodb/local.6, filling with zeroes...
Tue Jan 21 00:10:40.372 [FileAllocator] done allocating datafile /var/lib/mongodb/local.6, size: 2047MB,  took 0.014 secs
Tue Jan 21 00:10:40.372 [FileAllocator] allocating new datafile /var/lib/mongodb/local.7, filling with zeroes...
Tue Jan 21 00:10:40.498 [FileAllocator] done allocating datafile /var/lib/mongodb/local.7, size: 2047MB,  took 0.121 secs
Tue Jan 21 00:10:40.499 [FileAllocator] allocating new datafile /var/lib/mongodb/local.8, filling with zeroes...
Tue Jan 21 00:10:40.546 [FileAllocator] done allocating datafile /var/lib/mongodb/local.8, size: 2047MB,  took 0.046 secs
Tue Jan 21 00:10:40.546 [conn1] ERROR: mmap private failed with out of memory. (64 bit build)
Tue Jan 21 00:10:40.546 [conn1] Assertion: 13636:file /var/lib/mongodb/local.8 open/create failed in createPrivateMap (look in log for more information)
0xde0151 0xda188b 0xda1dcc 0xa5a63b 0xa5af9a 0xaba3b1 0x8d518d 0x8d5698 0x8d577f 0x8d5a1e 0xabbb00 0xac1429 0xa75908 0xc10af1 0x8dd4da 0x8de04d 0x8df582 0xa81f00 0xa867cc 0x9fa469
 /usr/bin/mongod(_ZN5mongo15printStackTraceERSo+0x21) [0xde0151]
 /usr/bin/mongod(_ZN5mongo11msgassertedEiPKc+0x9b) [0xda188b]
 /usr/bin/mongod() [0xda1dcc]
 /usr/bin/mongod(_ZN5mongo8MongoMMF13finishOpeningEv+0x1fb) [0xa5a63b]
 /usr/bin/mongod(_ZN5mongo8MongoMMF6createERKSsRyb+0x5a) [0xa5af9a]
 /usr/bin/mongod(_ZN5mongo13MongoDataFile4openEPKcib+0x141) [0xaba3b1]
 /usr/bin/mongod(_ZN5mongo8Database7getFileEiib+0xbd) [0x8d518d]
 /usr/bin/mongod(_ZN5mongo8Database8addAFileEib+0x38) [0x8d5698]
 /usr/bin/mongod(_ZN5mongo8Database12suitableFileEPKcibb+0xaf) [0x8d577f]
 /usr/bin/mongod(_ZN5mongo8Database11allocExtentEPKcibb+0x9e) [0x8d5a1e]
 /usr/bin/mongod(_ZN5mongo13_userCreateNSEPKcRKNS_7BSONObjERSsPb+0x7a0) [0xabbb00]
 /usr/bin/mongod(_ZN5mongo12userCreateNSEPKcNS_7BSONObjERSsbPb+0x2b9) [0xac1429]
 /usr/bin/mongod(_ZN5mongo11createOplogEv+0xa78) [0xa75908]
 /usr/bin/mongod(_ZN5mongo18CmdReplSetInitiate3runERKSsRNS_7BSONObjEiRSsRNS_14BSONObjBuilderEb+0x1da1) [0xc10af1]
 /usr/bin/mongod(_ZN5mongo12_execCommandEPNS_7CommandERKSsRNS_7BSONObjEiRSsRNS_14BSONObjBuilderEb+0x3a) [0x8dd4da]
 /usr/bin/mongod(_ZN5mongo7Command11execCommandEPS0_RNS_6ClientEiPKcRNS_7BSONObjERNS_14BSONObjBuilderEb+0x71d) [0x8de04d]
 /usr/bin/mongod(_ZN5mongo12_runCommandsEPKcRNS_7BSONObjERNS_11_BufBuilderINS_16TrivialAllocatorEEERNS_14BSONObjBuilderEbi+0x5f2) [0x8df582]
 /usr/bin/mongod(_ZN5mongo11runCommandsEPKcRNS_7BSONObjERNS_5CurOpERNS_11_BufBuilderINS_16TrivialAllocatorEEERNS_14BSONObjBuilderEbi+0x40) [0xa81f00]
 /usr/bin/mongod(_ZN5mongo8runQueryERNS_7MessageERNS_12QueryMessageERNS_5CurOpES1_+0xd7c) [0xa867cc]
 /usr/bin/mongod() [0x9fa469]
Tue Jan 21 00:10:40.563 [conn1] replSet replSetInitiate exception: file /var/lib/mongodb/local.8 open/create failed in createPrivateMap (look in log for more information)
Tue Jan 21 00:10:40.563 [conn1] command admin.$cmd command: { replSetInitiate: { _id: "rs0", version: 1.0, members: [ { _id: 0.0, host: "localhost:27017" } ] } } ntoreturn:1 keyUpdates:0 locks(micros) W:401$
Tue Jan 21 00:10:44.787 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)
Tue Jan 21 00:10:53.835 [conn1] replSet replSetInitiate admin command received from client
Tue Jan 21 00:10:53.835 [conn1] replSet replSetInitiate config object parses ok, 1 members specified
Tue Jan 21 00:10:53.835 [conn1] replSet replSetInitiate all members seem up
Tue Jan 21 00:10:53.835 [conn1] replSet info saving a newer config version to local.system.replset
Tue Jan 21 00:10:54.564 Invalid access at address: 0x18 from thread: conn1

Tue Jan 21 00:10:54.564 Got signal: 11 (Segmentation fault).

---

为什么MongoDB尝试在2GB中创建8个文件？我的机器用16GB内存运行，这就是问题所在吗？因为在一行中，错误“[conn1]error:mmap private因内存不足而失败。（64位构建）”看起来像是我的机器内存不足。但我只创建了一个副本集，其中包含一个成员和一个空数据库。Sombody知道那个bug吗？

问题不是RAM而是磁盘空间，它也不是bug

Tue Jan 21 00:10:40.164[conn1]正在创建大小为24630MB的复制oplog…

从MongoDB文档：

oplog（操作日志）是一个特殊的封顶集合，用于保存 修改存储在数据库中的数据的所有操作的滚动记录 数据库。MongoDB在主服务器上应用数据库操作，然后 在主操作日志上记录操作。次要成员 然后在异步进程中复制并应用这些操作。全部的 副本集成员包含oplog的副本，允许它们 维护数据库的当前状态

对于64位Linux、Solaris、FreeBSD和Windows系统，MongoDB 将可用可用磁盘空间的5%分配给oplog。如果这 数量小于1GB，则MongoDB分配1GB 空间

上经

复制需要Oplog（它是一个固定大小的上限集合），并且在创建复制集时会自动创建Oplog

oplogSize

可以通过配置选项进行设置（如果您只想尝试设置，无法释放更多磁盘空间）。 上面有个文件：

然而：

mongod第一次创建oplog后 oplog大小不会影响oplog的大小

通过

如果要在创建oplogSize后更改它，可以使用本教程：

但是，如果这是您的“游乐场”安装，最好删除旧MongoDB数据目录的内容（

/var/lib/MongoDB

），更改配置文件

/etc/MongoDB.conf

（或者在启动时将--oplogSize参数传递给mongo），然后“重新开始”使用较小的oplog或将MongoDB

dbpath

目录指向磁盘空间较大的位置