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This article introduces you MONGO DB too many mongodb page_faults error troubleshooting step by step example analysis, the content is very detailed, interested friends can refer to, hope to be helpful to you.

In the morning, morning call, a classmate of operation and maintenance, said that zabbix's MONGO monitoring alarm, the picture was sent to me, and the error reported was too many mongodb page_faults.

The root cause of page_faults is that instantaneous MONGO reads a large amount of data from disk, causing page_faults.

At this time, some MONGO DBA will react immediately to see if there is no full COLLECION scan, no good index, a large number of SCAN, will cause this problem.

But the strange thing about this problem is that the PAGE_FAULTS machine that reported the error does not have a query (not a primary library). Since there is no query, how did you get the page_faults?

A screenshot of the official explanation

Check immediately to see if there is something wrong with the page_faults of the standy library that just ran MONGO.

Here is the machine with the problem. (don't laugh at the fact that the new machine doesn't have that much page_faults.)

To compare the page_faults of the host

Sure enough, the machine with this problem has a lot of page_faults.

In addition, if you look at the state of memory, sure enough, you have already started to use SWAP.

Looking through mongostat, there is nothing wrong with the system.

Checking the log

As you can see, the log has pointed to advisoryHostFQDNS, and through the log, the error has been found all the time, and it takes 80 seconds to execute a command.

After query, there may be several reasons, because this advisoryHostFQDNs is the domain name resolution of each MONGODB machine in the cluster. This information is queried from OPS MANANGER, which indicates that we may have a problem with domain name resolution.

Here's the way to solve the problem: fill in the machine names of all cluster MONGODB on each machine and the HOSTS on OPS MANANGE instead of parsing it through DNS to see if you can solve the above problem.

This is the end of the sample analysis of MONGO DB too many mongodb page_faults error troubleshooting step by step. I hope the above content can be helpful to you and learn more knowledge. If you think the article is good, you can share it for more people to see.

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