Mongodb – Progress of mongodump operation jams at a random point

backupdumpmongodb

We are executing remote mongodumps to backup collections. For some time now sporadically one of these dumps stops to progress any further and remains to log out the same amount of documents processed over and over:

2016-06-27T06:35:06.428+0000    [##############.......]  col  1140198/1853120  (61.5%)
2016-06-27T06:35:09.428+0000    [##############.......]  col  1140198/1853120  (61.5%)
2016-06-27T06:35:12.428+0000    [##############.......]  col  1140198/1853120  (61.5%)

This time the dump is stuck at this point for about four hours and more than 5000 log lines showing 61.5% of progress.

I can still access the MongoDB Server from the backup machine, mongodb answers to queries, no annomalies in the logs.

MongoDB version 2.6.12

Best Answer

Seems that some other folks had this issue (here or here) without any clear resolution. Someone suggests adding --quiet to the mongodump command.

But maybe mongodump is not the correct way of doing it. From the documentation:

mongodump and mongorestore are simple and efficient tools for backing up and restoring small MongoDB deployments, but are not ideal for capturing backups of larger systems

Also:

When connected to a MongoDB instance, mongodump can adversely affect mongod performance. If your data is larger than system memory, the queries will push the working set out of memory, causing page faults

Some other methods of creating backups are detailed in the documentation. Maybe „Filesystem Snapshots” or „cp or rsync” are more suitable to your use case.

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