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

Question

我尝试在运行 Debian 7.3 的新虚拟服务器上设置 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 尝试创建 8 个文件 2GB？我的机器运行 16GB 内存，这可能是问题所在吗？因为在一行中出现错误“[conn1] ERROR:mmap private failed with out of memory。(64 位构建)”看起来我的机器内存不足。但我只创建了一个包含一个成员和一个空数据库的副本集。有人知道那个错误吗？

Answer 1

问题不是 RAM，而是磁盘空间，也不是错误。

1 月 21 日星期二 00:10:40.164 [conn1] 创建大小为 24630MB 的复制 oplog...

来自 MongoDB 文档:

The oplog (operations log) is a special capped collection that keeps a rolling record of all operations that modify the data stored in your databases. MongoDB applies database operations on the primary and then records the operations on the primary’s oplog. The secondary members then copy and apply these operations in an asynchronous process. All replica set members contain a copy of the oplog, allowing them to maintain the current state of the database.

For 64-bit Linux, Solaris, FreeBSD, and Windows systems, MongoDB allocates 5% of the available free disk space to the oplog. If this amount is smaller than a gigabyte, then MongoDB allocates 1 gigabyte of space.

以上来自http://docs.mongodb.org/manual/core/replica-set-oplog/

复制需要 Oplog(它是一个固定大小的上限集合)，这是在您创建副本集时自动创建的。 oplogSize 可以通过配置选项设置(如果您只想试验一下设置并且不能释放更多磁盘空间)。这是关于它的文档:http://docs.mongodb.org/manual/reference/configuration-options/#oplogSize

但是:

Once the mongod has created the oplog for the first time, changing oplogSize will not affect the size of the oplog.

通过http://docs.mongodb.org/manual/reference/configuration-options/#oplogSize

如果您想在创建 oplogSize 后更改它，您可以使用本教程:http://docs.mongodb.org/manual/tutorial/change-oplog-size/

但是，如果这是您的“ Playground ”安装，最好删除旧 MongoDB 数据目录 (/var/lib/mongodb) 的内容，更改配置文件 /etc/mongodb .conf (或在它启动时将 --oplogSize 参数传递给 mongo)，然后使用较小的 oplog 进行“全新开始”，或者将您的 MongoDB dbpath 目录指向一个包含更多操作日志的地方磁盘空间。