Mongodb ERROR: child process failed, exited with error number 51 - mongodb

Question

mongodb was closed by some reason. system shutdown abnormally.
when i try to restart mongodb use:
mongod -f /usr/local/mongodb/etc/mongo.conf
got
about to fork child process, waiting until server is ready for connections.
forked process: 28402
ERROR: child process failed, exited with error number 51
To see additional information in this output, start without the "--fork" option.
mongodb.log:
2019-02-19T13:22:24.105+0800 I CONTROL [main] ***** SERVER RESTARTED *****
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] MongoDB starting : pid=28131 port=27017 dbpath=/usr/local/mongodb/data/mongodata 64-bit host=nginx.xchs
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] db version v3.6.2
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] git version: 489d177dbd0f0420a8ca04d39fd78d0a2c539420
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] OpenSSL version: OpenSSL 1.0.1e-fips 11 Feb 2013
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] allocator: tcmalloc
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] modules: none
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] build environment:
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] distmod: rhel62
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] distarch: x86_64
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] target_arch: x86_64
2019-02-19T13:22:24.112+0800 I CONTROL [initandlisten] options: { config: "/usr/local/mongodb/etc/mongo.conf", net: { bindIp: "0.0.0.0" }, processManagement: { fork: true }, storage: { dbPath: "/usr/local/mongodb/data/mongodata" }, systemLog: { destination: "file", logAppend: true, path: "/usr/local/mongodb/data/log/mongolog/mongodb.log" } }
2019-02-19T13:22:24.112+0800 W - [initandlisten] Detected unclean shutdown - /usr/local/mongodb/data/mongodata/mongod.lock is not empty.
2019-02-19T13:22:24.113+0800 I - [initandlisten] Detected data files in /usr/local/mongodb/data/mongodata created by the 'wiredTiger' storage engine, so setting the active storage engine to 'wiredTiger'.
2019-02-19T13:22:24.113+0800 W STORAGE [initandlisten] Recovering data from the last clean checkpoint.
2019-02-19T13:22:24.113+0800 I STORAGE [initandlisten]
2019-02-19T13:22:24.113+0800 I STORAGE [initandlisten] ** WARNING: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine
2019-02-19T13:22:24.113+0800 I STORAGE [initandlisten] ** See http://dochub.mongodb.org/core/prodnotes-filesystem
2019-02-19T13:22:24.113+0800 I STORAGE [initandlisten] wiredtiger_open config: create,cache_size=3424M,session_max=20000,eviction= (threads_min=4,threads_max=4),config_base=false,statistics=(fast),log= (enabled=true,archive=true,path=journal,compressor=snappy),file_manager= (close_idle_time=100000),statistics_log=(wait=0),verbose=(recovery_progress),
2019-02-19T13:22:24.602+0800 E STORAGE [initandlisten] WiredTiger error (0) [1550553744:602025][28131:0x7f41a84cea80], file:WiredTiger.wt, WT_CURSOR.next: read checksum error for 24576B block at offset 1671168: block header checksum of 3727800471 doesn't match expected checksum of 605632
2019-02-19T13:22:24.602+0800 E STORAGE [initandlisten] WiredTiger error (0) [1550553744:602085][28131:0x7f41a84cea80], file:WiredTiger.wt, WT_CURSOR.next: WiredTiger.wt: encountered an illegal file format or internal value: (__wt_block_read_off, 227)
2019-02-19T13:22:24.602+0800 E STORAGE [initandlisten] WiredTiger error (-31804) [1550553744:602097][28131:0x7f41a84cea80], file:WiredTiger.wt, WT_CURSOR.next: the process must exit and restart: WT_PANIC: WiredTiger library panic
2019-02-19T13:22:24.602+0800 F - [initandlisten] Fatal Assertion 28558 at src/mongo/db/storage/wiredtiger/wiredtiger_util.cpp 361
2019-02-19T13:22:24.602+0800 F - [initandlisten]
***aborting after fassert() failure
how to resolve this problem?

Answer 1

Open your config file in VIM or in a plain text editor,
got to this line:
storage:
dbPath: THE_PATH_TO_THE_DIRECTORY_YOU_STORE_YOUR_DB
for example:
/var/mongodb/db/mydb
Go to your terminal to confirm if the path under dbPath exists, type:
ls THE_PATH_TO_THE_DIRECTORY_YOU_STORE_YOUR_DB
for example for my case here:
ls /var/mongodb/db/mydb
If the result is directory does not exist, then just recreate it:
mkdir -p THE_PATH_TO_THE_DIRECTORY_YOU_STORE_YOUR_DB
for example:
mkdir -p /var/mongodb/db/mydb
If you found that the directory exists then it was corrupted during shutdown,as highlighted in the answere above.
Go to your terminal and run the following command:
mongod --dbpath /data/db --repair
Please Refer the above from the Mongo DB Offcial Docs

Answer 2

Please Try
mongod --repair --dbpath /path/to/data/db