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hostInfo

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  • Definition
  • Syntax
  • Output

Definition

hostInfo
Returns:A document with information about the underlying system that the mongod or mongos runs on. Some of the returned fields are only included on some platforms.

You must run the hostInfo command, which takes no arguments, against the admin database.

Syntax

db.adminCommand(
   {
     hostInfo: 1
   }
)

Output

In mongosh you can use db.hostInfo() as a helper to access hostInfo. The output of hostInfo on a Linux system will resemble the following:

{
   "system" : {
          "currentTime" : ISODate("<timestamp>"),
          "hostname" : "<hostname>",
          "cpuAddrSize" : <number>,
          "memSizeMB" : <number>,
          "memLimitMB" : <number>,  // Available starting in MongoDB 4.0.9 (and 3.6.13)
          "numCores" : <number>,
          "cpuArch" : "<identifier>",
          "numaEnabled" : <boolean>
   },
   "os" : {
          "type" : "<string>",
          "name" : "<string>",
          "version" : "<string>"
   },
   "extra" : {
          "versionString" : "<string>",
          "libcVersion" : "<string>",
          "kernelVersion" : "<string>",
          "cpuFrequencyMHz" : "<string>",
          "cpuFeatures" : "<string>",
          "pageSize" : <number>,
          "numPages" : <number>,
          "maxOpenFiles" : <number>
   },
   "ok" : <return>
}

Output Fields

hostInfo

The document returned by the hostInfo.

hostInfo.system

An embedded document providing information about the underlying environment of the system running the mongod or mongos

hostInfo.system.currentTime

A timestamp of the current system time.

hostInfo.system.hostname

The system name, which should correspond to the output of hostname -f on Linux systems.

hostInfo.system.cpuAddrSize

A number reflecting the architecture of the system. Either 32 or 64.

hostInfo.system.memSizeMB

The total amount of system memory (RAM) in megabytes.

hostInfo.system.memLimitMB

The memory usage limit in megabytes.

For example, running in a container may impose memory limits that are lower than the total system memory. This memory limit, rather than the total system memory, is used as the maximum RAM available to calculate WiredTiger internal cache.

Available starting in MongoDB 4.0.9 (and 3.6.13)

hostInfo.system.numCores

The total number of available logical processor cores.

hostInfo.system.cpuArch

A string that represents the system architecture. Either x86 or x86_64.

hostInfo.system.numaEnabled

A boolean value. false if NUMA is interleaved (i.e. disabled), otherwise true.

hostInfo.os

An embedded document that contains information about the operating system running the mongod and mongos.

hostInfo.os.type

A string representing the type of operating system, such as Linux or Windows.

hostInfo.os.name

If available, returns a display name for the operating system.

hostInfo.os.version

If available, returns the name of the distribution or operating system.

hostInfo.extra

An embedded document with extra information about the operating system and the underlying hardware. The content of the extra embedded document depends on the operating system.

hostInfo.extra.cpuString

A string containing a human-readable description of the system's processor.

cpuString only appears on macOS systems.

hostInfo.extra.versionString

A complete string of the operating system version and identification. On Linux and macOS systems, this contains output similar to uname -a.

hostInfo.extra.libcVersion

The release of the system libc.

libcVersion only appears on Linux systems.

hostInfo.extra.kernelVersion

The release of the Linux kernel in current use.

kernelVersion only appears on Linux systems.

hostInfo.extra.alwaysFullSync

alwaysFullSync only appears on macOS systems.

hostInfo.extra.nfsAsync

nfsAsync only appears on macOS systems.

hostInfo.extra.cpuFrequencyMHz

Reports the clock speed of the system's processor in megahertz.

hostInfo.extra.cpuFeatures

Reports the processor feature flags. On Linux systems this the same information that /proc/cpuinfo includes in the flags fields.

hostInfo.extra.pageSize

Reports the default system page size in bytes.

hostInfo.extra.physicalCores

Reports the number of physical, non-HyperThreading, cores available on the system.

physicalCores only appears on macOS systems.

hostInfo.extra.numPages

numPages only appears on Linux systems.

hostInfo.extra.maxOpenFiles

Reports the current system limits on open file handles. See UNIX ulimit Settings for more information.

maxOpenFiles only appears on Linux systems.

hostInfo.extra.scheduler

Reports the active I/O scheduler. scheduler only appears on OS X systems.

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