ERROR: child process failed, exited with error number 100

  mongodb, question

1. mongoDB is configured in replica set mode and started successfully
2. insert data into it, master and slave2 are normal, slave1 goes down abnormally
3. restart slave1 and report the following error

about to fork child process, waiting until server is ready for connections.
 forked process: 756411
 ERROR: child process failed, exited with error number 1

4. after deleting mongo.lock and mongodb.log, start in repair mode and report the following error

about to fork child process, waiting until server is ready for connections.
 forked process: 756411
 ERROR: child process failed, exited with error number 100

5. check mongodb.log for the following contents and report a pile of No space left on device.

2017-02-28T15:22:10.933+0800 E STORAGE  [repl writer worker 3] WiredTiger (28) [1488266530:932986][21657:0x7f903153f700], WT_SESSION.commit_transaction: journal/WiredTigerLog.0000000003: ha
 ndle-write: pwrite: failed to write 45952 bytes at offset 8572928: No space left on device
 2017-02-28T15:22:10.933+0800 I -        [repl writer worker 3] Invariant failure: s->commit_transaction(s, NULL) resulted in status UnknownError: 28: No space left on device at src/mongo/db
 /storage/wiredtiger/wiredtiger_recovery_unit.cpp 213
 2017-02-28T15:22:10.933+0800 E STORAGE  [repl writer worker 0] WiredTiger (28) [1488266530:933845][21657:0x7f9032d42700], WT_SESSION.commit_transaction: journal/WiredTigerLog.0000000003: ha
 ndle-write: pwrite: failed to write 129408 bytes at offset 8753152: No space left on device
 2017-02-28T15:22:10.933+0800 I -        [repl writer worker 0] Invariant failure: s->commit_transaction(s, NULL) resulted in status UnknownError: 28: No space left on device at src/mongo/db
 /storage/wiredtiger/wiredtiger_recovery_unit.cpp 213
 2017-02-28T15:22:10.934+0800 E STORAGE  [repl writer worker 7] WiredTiger (28) [1488266530:934510][21657:0x7f902f53b700], WT_SESSION.commit_transaction: journal/WiredTigerLog.0000000003: ha
 ndle-write: pwrite: failed to write 131840 bytes at offset 8882560: No space left on device
 2017-02-28T15:22:10.934+0800 I -        [repl writer worker 7] Invariant failure: s->commit_transaction(s, NULL) resulted in status UnknownError: 28: No space left on device at src/mongo/db
 /storage/wiredtiger/wiredtiger_recovery_unit.cpp 213
 2017-02-28T15:22:10.935+0800 E STORAGE  [repl writer worker 1] WiredTiger (28) [1488266530:935197][21657:0x7f9032541700], WT_SESSION.commit_transaction: journal/WiredTigerLog.0000000003: ha
 ndle-write: pwrite: failed to write 131840 bytes at offset 9014400: No space left on device
 2017-02-28T15:22:10.935+0800 I -        [repl writer worker 1] Invariant failure: s->commit_transaction(s, NULL) resulted in status UnknownError: 28: No space left on device at src/mongo/db
 /storage/wiredtiger/wiredtiger_recovery_unit.cpp 213
 2017-02-28T15:22:10.936+0800 E STORAGE  [repl writer worker 9] WiredTiger (28) [1488266530:936508][21657:0x7f902e539700], WT_SESSION.commit_transaction: journal/

6. Has anyone encountered similar problems? We still hope for an answer.

Your disk space is low, causing the log submission to fail.df -hCheck the disk space. /mongo/db
/storage/wiredtiger/ Whether the corresponding disk is full or not, you can usually delete mongo’s log file to free up some disk space.