[SERVER-30363] MongoDB journal data size increase everyday Created: 27/Jul/17  Updated: 22/Aug/17  Resolved: 22/Aug/17

Status: Closed
Project: Core Server
Component/s: Storage, WiredTiger
Affects Version/s: 3.4.4
Fix Version/s: None

Type: Question Priority: Major - P3
Reporter: Sandip Kushvah Assignee: Bruce Lucas (Inactive)
Resolution: Incomplete Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Participants:

 Description   

I am using mongodb 3.4 with storage engine wired tiger.when i check every day of storage consumed by mongodb ,i found journal directory size increase everyday. Currently it's size is 1.8Gb.
From Mongo DB document

WiredTiger journal files for MongoDB have a maximum size limit of approximately 100 MB. Once the file exceeds that limit, WiredTiger creates a new journal file.

WiredTiger automatically removes old journal files to maintain only the files needed to recover from last checkpoint.

WiredTiger will pre-allocate journal files.

I want to know why this size increased up to this level ? .why old files not removed ?



 Comments   
Comment by Bruce Lucas (Inactive) [ 28/Jul/17 ]

Hi Sandip,

In order for us to continue our diagnosis, I have generated a secure upload portal for this ticket. Can you please

  • archive and upload the directory $dbpath/diagnostic.data for the affected instance (preferably the one on 3.4.6).
  • compress and upload all available mongod log files for that same instance
  • show us the output of ls -lR $dbpath (either attach to this ticket or upload to the secure portal)

Thanks,
Bruce

Comment by Sandip Kushvah [ 28/Jul/17 ]

Hi Bruce,
Mongodb is running on AWS EC2 instance. I have two instance in which mongodb 3.4.4 is running in one instance and 3.4.6 is running in another instance.Both are stand alone instances.
Is there any configuration set up require for journal file set up ? If not why old file not removed and size increase everyday?

Comment by Bruce Lucas (Inactive) [ 27/Jul/17 ]

Hi Sandip,

I have a couple of questions about your installation:

  • Are you running on Azure?
  • Do you see messages like the following in syslog:

    May 17 14:37:10 db-rs0-2 systemd[1]: Time has been changed
    

If so, you may be encountering WT-3327, which can produce the same symptom you are seeing as described in SERVER-29230. You can avoid this issue by either

  • upgrading to 3.4.6, which contains the fix for WT-3327, or
  • disabling Azure time sync as described in the last two comments in SERVER-29230.

Please let us know if this resolves your issue.

Bruce

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