---
name: "mongoperf"
section: "1"
platform: "linux"
package: "mongodb-clients"
version: "1:3.2.11-2+deb9u1"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/mongoperf"
---

# mongoperf(1)

MongoDB

## NAME

mongoperf - MongoDB

## SYNOPSIS

*mongoperf* is a utility to check disk I/O performance independently of MongoDB.

It times tests of random disk I/O and presents the results. You can use *mongoperf* for any case apart from MongoDB. The *mmf* **true** mode is completely generic. In that mode is it somewhat analogous to tools such as *bonnie++* (albeit mongoperf is simpler).

Specify options to *mongoperf* using a JavaScript document.

- See also

  - •

    *bonnie*

  - •

    *bonnie++*

  - •

    *Output from an example run*

  - •

    *Checking Disk Performance with the mongoperf Utility*

## OPTIONS

- **mongoperf**

  - **--help**

  Displays the options to *mongoperf*.  Specify options to *mongoperf* with a JSON document described in the *Configuration Fields* section.

- **\<jsonconfig\>**

  *mongoperf* accepts configuration options in the form of a file that holds a *JSON* document. You must stream the content of this file into *mongoperf*, as in the following operation:

  ```
  mongoperf < config
  ```

  In this example **config** is the name of a file that holds a JSON document that resembles the following example:

  ```
  {
    nThreads:<n>,
    fileSizeMB:<n>,
    sleepMicros:<n>,
    mmf:<bool>,
    r:<bool>,
    w:<bool>,
    recSizeKB:<n>,
    syncDelay:<n>
  }
  ```

  See the *Configuration Fields* section for documentation of each of these fields.

## CONFIGURATION FIELDS

- **mongoperf.nThreads**

  *Type:* Integer.

  *Default:* 1

  Defines the number of threads *mongoperf* will use in the test. To saturate your system's storage system you will need multiple threads. Consider setting *nThreads* to **16**.

- **mongoperf.fileSizeMB**

  *Type:* Integer.

  *Default:* 1 megabyte (i.e. 10242 bytes)

  Test file size.

- **mongoperf.sleepMicros**

  *Type:* Integer.

  *Default:* 0

  *mongoperf* will pause for the number of specified *sleepMicros* divided by the *nThreads* between each operation.

- **mongoperf.mmf**

  *Type:* Boolean.

  *Default:* **false**

  Set *mmf* to **true** to use memory mapped files for the tests.

  Generally:

  - •

    when *mmf* is **false**, *mongoperf* tests direct, physical, I/O, without caching. Use a large file size to test heavy random I/O load and to avoid I/O coalescing.

  - •

    when *mmf* is **true**, *mongoperf* runs tests of the caching system, and can use normal file system cache. Use **mmf** in this mode to test file system cache behavior with memory mapped files.

- **mongoperf.r**

  *Type:* Boolean.

  *Default:* **false**

  Set *r* to **true** to perform reads as part of the tests.

  Either *r* or *w* must be **true**.

- **mongoperf.w**

  *Type:* Boolean.

  *Default:* **false**

  Set *w* to **true** to perform writes as part of the tests.

  Either *r* or *w* must be **true**.

- **mongoperf.syncDelay**

  *Type:* Integer.

  *Default:* 0

  Seconds between disk flushes. *syncDelay* is similar to **syncDelay** for **mongod**.

  The *syncDelay* controls how frequently *mongoperf* performs an asynchronous disk flush the memory mapped file used for testing. By default, **mongod** performs this operation every every 60 seconds. Use *syncDelay* to test basic system performance of this type of operation.

  Only use *syncDelay* in conjunction with *mmf* set to **true**.

  The default value of **0** disables this

## USE

```
mongoperf < jsonconfigfile
```

Replace **jsonconfigfile** with the path to the *mongoperf* configuration. You may also invoke *mongoperf* in the following form:

```
echo "{nThreads:16,fileSizeMB:1000,r:true}" | ./mongoperf
```

In this operation:

- •

  *mongoperf* tests direct physical random read io's, using 16 concurrent reader threads.

- •

  *mongoperf*  uses a 1 gigabyte test file.

Consider using **iostat**, as invoked in the following example to monitor I/O performance during the test.

```
iostat -xm 2
```

## AUTHOR

MongoDB Documentation Project

## COPYRIGHT

2011-2013, 10gen, Inc.