Re: Performance Stats

[Stephen Steneker]

It is my first post here I believe it is a DBA related question. 

Reading docs from mongodb.org I understand that if I want to know about I/O stats about my MongoDB I should look at iostat. It is very important to understand how many reads/writes are going to disk, etc, etc.

Is there any command  or tool where I can see the working set size?

Hi Rodrigo,

There is a wiki page with some information on checking server usage and estimating working set size:
 http://www.mongodb.org/display/DOCS/Checking+Server+Memory+Usage#CheckingServerMemoryUsage-WorkingSetSize

It looks like you may have already come across the Monitoring+Diagnostics info:
 http://www.mongodb.org/display/DOCS/Monitoring+and+Diagnostics

To understand your typical working set and server performance over time you should be using monitoring tools such as MMS and/or Munin.

Cheers,
Stephen 

[Rodrigo]

Sthepen,

How are you?

Thank you for your reply.

Sorry for my newbie questions, it is because I'm trying to find out how a Enterprise Storage like NetApp can aggregate values to mongodb implementations. It is very important to me understand how analyze I/O at MongoDB. I'm wanna be a MongoDB Database Administrator. :-)

Is there any way to see which collections are mostly accessed? 

Thanks,

Rodrigo

NetApp - Enjoy it!

PS. Sorry for any English mistakes, it is not my native language.

[Stephen Steneker]

Sorry for my newbie questions, it is because I'm trying to find out how a Enterprise Storage like NetApp can aggregate values to mongodb implementations. It is very important to me understand how analyze I/O at MongoDB. I'm wanna be a MongoDB Database Administrator. :-)

Is there any way to see which collections are mostly accessed? 

Hi Rodrigo,

The previous links I provided should be a good starting point for monitoring & stats documentation.

A few items which might be of particular interest for you from those pages are:

 - the `mongostat` utility which provides a snapshot of DB activity counters similar to vmstat: http://docs.mongodb.org/manual/reference/mongostat/
 - 10gen's free hosted MongoDB Monitoring Service (MMS) which can provide helpful insight into statistics over time: https://mms.10gen.com/

MongoDB uses memory-mapped files for disk I/O, so the general performance metrics on I/O, Ram, etc can be monitored using your normal O/S admin tools.

To see which collections are accessed you can enable query profiling:
   http://www.mongodb.org/display/DOCS/Database+Profiler

You can query the profile data to get some detail on access patterns by db+collection ("namespace"), but the information is probably more detailed than what you are after.

There are a few community-contributed tools that can work with the profiler data and help make recommendations on indexing:

  http://blog.mongolab.com/2012/07/remote-dex/

  http://late.am/post/2011/09/22/professor-a-mongodb-profile-viewer

Profiling uses a capped collection so will keep a limited amount of history; you can increase the size if needed:

  http://www.mongodb.org/display/DOCS/Database+Profiler#DatabaseProfiler-Changingthesystem.profileCollectionSize

There are some great presentations across many topics in the 10gen presentation archive: http://www.10gen.com/presentations.

You mentioned you are based in Brazil.  FYI, there is also an upcoming user group meeting in Sãu Paulo at the end of the month which will include a few visiting 10gen team members:
 http://www.meetup.com/SP-MongoDB/

I would suggest you set up a local instance of MongoDB to test with (if you haven't already!).

Cheers,

Stephen

[Scott Hernandez]

In particular, mongotop will show the currently accessed collections
listed by most active at the top:
http://docs.mongodb.org/manual/reference/mongotop/

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[Rodrigo]

Sthepen,

Thank you very much!

Very useful links....

Rodrigo

NetApp -Enjoy it!