Mongodb – Unable to start the mongo services on debian server

debianlinuxmongodb

Mongo DB keep on crashing automatically and all database and collection remove automatically.This is happening randomly and when I check mongod.log I can see it's automatically dropped.

Today I got the error message that mongo service unable to start, and when I start it services it give me the error

Job for mongod.service failed. See 'systemctl status mongod.service' and 'journalctl -xn' for details.

when I type this command

systemctl status mongod.service

Debian Server Configuration are: 40GB HHD 4GB RAM

I have around 2 million data as of now in mongoDB and it will increase day by day.

I have down so much of google but didn't find the perfect solution and as I'm not an expert at server level ,so can some give a suggestion or solution to how can I get rid with this problem.

Best Answer

That first log file tells that "client" connects to the server and gives dropDatabase command, so check your application. Why it executes dropDatabase.

What comes to the second problem, you need to check your mongodb.log, what it tells for the reason, why mongodb cannot start. Wild guess is ownership of some files (data, lock, log), all files must be owned by user what you use to start mongod process (probably mongodb -user) Name and location of mongodb.log, you can find from /etc/mongod.conf -file

journal

journal Default: (on 64-bit systems) true

Default: (on 32-bit systems) false

Set to true to enable operation journaling to ensure write durability and data consistency.

Set to false to prevent the overhead of journaling in situations where durability is not required. To reduce the impact of the journaling on disk usage, you can leave journal enabled, and set smallfiles to true to reduce the size of the data and journal files.

Note You must use nojournal to disable journaling on 64-bit systems.

journalCommitInterval

Default: 100 or 30

Set this value to specify the maximum amount of time for mongod to allow between journal operations. Lower values increase the durability of the journal, at the possible expense of disk performance.

The default journal commit interval is 100 milliseconds if a single block device (e.g. physical volume, RAID device, or LVM volume) contains both the journal and the data files.

If different block devices provide the journal and data files the default journal commit interval is 30 milliseconds.

This option accepts values between 2 and 300 milliseconds.

To force mongod to commit to the journal more frequently, you can specify j:true. When a write operation with j:true is pending, mongod will reduce journalCommitInterval to a third of the set value.

For more clarification, please read Recover MongoDB Data following Unexpected Shutdown. You may need to run validate() on your data collections to verify integrity.

You should also read about Journaling

SUGGESTIONS

Looking back at this phrase If different block devices provide the journal and data files the default journal commit interval is 30 milliseconds.
You should make store the MongoDB journals on a different disk from the Data.
You may also want to shrink the journaling files if you haven't already done so.
You should see if the journal files are RAM-based. If they are and if you ran out of memory, that may explain your crash.
See Documentation on --smallfiles

Mysql – Unable to start thesql

I found my answer and I want to laugh on myself... What a silly mistake I did! Sharing this solution so that others can save their time. I just prefix sudo command in the below statement and mysql started.

$ sudo /etc/rc.d/init.d/mysql start

Input password: Starting MySQL. I checked and found that MySQL is running by issuing below command:

$ mysqladmin -u root -pjoomla1 ping

mysqld is alive

Best Answer

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Mongodb – Mongo DB Can’t Start

journal

journalCommitInterval

SUGGESTIONS

Mysql – Unable to start thesql

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