Skip to content
a stripped-down version of bonnie/bonnie++ implemented in Golang
Branch: master
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Type Name Latest commit message Commit time
Failed to load latest commit information.


GoBonnieGo is a minimal Golang implementation of Tim Bray's bonnie (bonnie is written in C).

It measures disk throughput by reading and writing files.

It presents three disk metrics:

  1. Sequential Write (higher is better)
  2. Sequential Read (higher is better)
  3. IOPS (I/O Operations per Second) (higher is better)

Getting GoBonnieGo

The easiest way to get GoBonnieGo is to download the pre-built binaries in the Releases section. In the following example, we are logged into a Linux box and we download and run the Linux binary:

curl -o gobonniego -L
chmod +x gobonniego

Alternatively, you can run GoBonnieGo from source if you're a Golang developer:

go get
cd $GOPATH/src/
go run gobonniego/gobonniego.go  # "Go Bonnie Go, Go"!


GoBonnieGo can be invoked without parameters; its defaults are reasonable.


Typical output:

2018/04/12 06:20:09 gobonniego starting. version: 1.0.9, runs: 1, seconds: 0, threads: 4, disk space to use (MiB): 512
Sequential Write MB/s: 748.22
Sequential Read MB/s: 1025.19
IOPS: 23832

Running with the verbose option (-v) will print additional timestamped information to STDERR:

gobonniego -v


2018/04/12 06:20:09 gobonniego starting. version: 1.0.9, runs: 1, seconds: 0, threads: 4, disk space to use (MiB): 512
2018/02/24 17:20:20 Number of CPU cores: 8
2018/02/24 17:20:20 Total system RAM (MiB): 65536
2018/02/24 17:20:20 Bonnie working directory: /var/folders/lp/k0g2hcfs0bz1c4zn90pnh32w0000gn/T/gobonniegoParent337382325
2018/02/24 17:20:21 Written (MiB): 512
2018/02/24 17:20:21 Written (MB): 536.870912
2018/02/24 17:20:21 Duration (seconds): 1.029243
Sequential Write MB/s: 521.62
2018/02/24 17:20:21 Read (MiB): 512
2018/02/24 17:20:21 Read (MB): 536.870912
2018/02/24 17:20:21 Duration (seconds): 0.023219
Sequential Read MB/s: 23121.95
2018/02/24 17:20:37 operations 16927770
2018/02/24 17:20:37 Duration (seconds): 15.940455
IOPS: 1061938

You may specify the number of test runs. This is useful when gathering a large sample set.

gobonniego -v -runs 2

You may specify the minimum number of seconds the test should run with the -seconds flag. For example, if you pass the flag -seconds 3600, GoBonnieGo will run continuously until 1 hour has elapsed, at which point the program will wait for the final test suite (write, read, IOPS) to finish and then exit.

GoBonnieGo may take much longer to complete than one would expect. For example, if you set -seconds 60 and run GoBonnieGo on a machine with a very slow disk (some disks take over an hour to finish a single suite), then GoBonnieGo will not stop after 60 seconds; instead, it will continue running until that particular suite is finished.

When used in conjunction with -runs flag, GoBonnieGo will continue to run until both the time has elapsed and the number of runs have completed.

In the following example, GoBonnieGo will run for at least one day (24 hours, i.e. 86,400 seconds):

gobonniego -v -seconds 86400

You may specify the placement of GoBonnieGo's test files. This is useful if the default filesystem is too small or if you want to test a specific filesystem/disk. GoBonnieGo will clean up after itself, and will not delete the directory it's told to run in (you can safely specify /tmp or / as the directory). Here are some examples:

gobonniego -dir D:\
gobonniego -dir /tmp
gobonniego -dir /zfs/tank
gobonniego -dir /Volumes/USB
gobonniego -dir /var/vcap/store/

You may specify the number of threads (Goroutines) to run with the -threads flag. In this example, we spawn 8 threads:

gobonniego -threads 8

You may choose to have JSON-formatted output by specifying the -json flag. In the following example, we pass the JSON output to the popular jq tool which prettifies the JSON output:

gobonniego -json | jq -r .


  "version": "1.0.9",
  "start_time": "2018-04-12T06:46:00.274348275-07:00",
  "gobonniego_directory": "/var/folders/zp/vmj1nyzj6p567k5syt3hvq3h0000gn/T/gobonniegoParent456127644/gobonniego",
  "disk_space_used_gib": 0.5,
  "num_readers_and_writers": 4,
  "physical_memory_bytes": 17179869184,
  "iops_duration_seconds": 0.5,
  "results": [
      "write_megabytes_per_second": 1312.8274662905276,
      "read_megabytes_per_second": 8279.508528024262,
      "iops": 382508.71617051313,
      "write_seconds": 0.408942474,
      "read_seconds": 0.064843331,
      "io_seconds": 0.724610939,
      "start_time": "2018-04-12T06:46:00.274972832-07:00",
      "write_bytes": 536870912,
      "read_bytes": 536870912,
      "io_operations": 277170

jq can also convert the human-readable timestamps into the number of seconds elapsed since the benchmark was started (a useful conversion when creating line charts):

gobonniego -json | jq -r '( .start_time | sub("\\.[0-9]*";"") | fromdate ) as $start_time |
  .results = [ .results[] | .start_time = ( .start_time | sub("\\.[0-9]*";"") | fromdate - $start_time ) ]'

You may specify the amount of disk space GoBonnieGo should use with the -size flag which takes an integer argument (in GiB). This can be used to iterate rapidly while testing. For example, to constrain GoBonnieGo to use 0.5 GiB of disk space, type the following:

gobonniego -size 0.5

You may specify the duration of the IOPS test. By default it runs for 15 seconds, but this can be overridden in order to iterate rapidly while testing. For example, to trim the duration of the IOPS test to 1/2 second, type the following:

gobonniego --iops-duration=0.5

-version will display the current version of GoBonnieGo:

gobonniego -version


gobonniego version 1.0.9

gobonniego -h will print out the available command line options and their current default values:

Usage of ./gobonniego:
  -dir string
        The directory in which gobonniego places its temporary files, should have at least '-size' space available (default "/var/folders/zp/vmj1nyzj6p567k5syt3hvq3h0000gn/T/gobonniegoParent120217156")
  -iops-duration float
        The duration in seconds to run the IOPS benchmark, set to 0.5 for quick feedback during development (default 15)
        Version. Will print JSON-formatted results to stdout. Does not affect diagnostics to stderr
  -runs int
        The number of test runs (default 1)
  -size float
        The amount of disk space to use (in GiB), defaults to twice the physical RAM (default 32)
  -threads int
        The number of concurrent readers/writers, defaults to the number of CPU cores (default 4)
  -v    Verbose. Will print to stderr diagnostic information such as the amount of RAM, number of cores, etc.
        Version. Will print the current version of gobonniego and then exit

Technical Notes

GoBonnieGo detects the number of CPU cores and the amount of RAM.

The number of cores may not match the number of physical cores. For example, an Intel core i5 with two physical cores and hyperthreading is detected as 4 cores.

GoBonnieGo spawns one thread for each core unless overridden by the -threads flag.

GoBonnieGo writes twice the amount of RAM unless overridden with the -size flag. For example, on a system with 16 GiB of RAM, GoBonnieGo would write 32 GiB of data. This is to reduce the effect of the buffer cache, which may give misleadingly good results.

If the sequential read performance is several multiples of the sequential write performance, it's likely that the buffer cache has skewed the results.

The buffer cache also skews the results of the IOPS metric — the number reported by GoBonnieGo is often much too high, and a reasonable rule of thumb would be to halve the IOPS value reported by GoBonnieGo (e.g. 200k IOPS would become 100k IOPS) (assumptions: GoBonnieGo dataset size is twice RAM, that half the dataset is in the buffer cache, that any given operation has a 50% chance of hitting the cache instead of the disk, that the operation is a read (true 90% of the time), and that any operation hitting the buffer cache returns instantaneously (takes zero seconds to process)).

If run as root on Linux or macOS systems, GoBonnieGo will flush the buffer cache before running the read test or the IOPS test, and will also flush the buffer cache every three seconds. It accomplishes this on linux by writing 3 to /proc/sys/vm/drop_caches; on macOS, it runs the purge command. The results given by GoBonnieGo under these conditions will more closely reflect the performance of the underlying hardware (i.e. you should not halve the IOPS value), but there is always a risk when running commands as root. Caveat Utor.

GoBonnieGo divides the total amount to write by the number of threads. For example, a 4-core system with 8 GiB of RAM would have four threads each of which would concurrently write 4 GiB of data for a total of 16 GiB.

GoBonnieGo writes with buffered I/O; however, it waits for bufio.Flush() to complete before recording the duration.

GoBonnieGo creates a 64 kiB chunk of random data which it writes in succession to disk. It's random in order to avoid inflating the results for filesystems which enable compression (e.g. ZFS). We are aware that we are unfairly handicapping filesystems which enable compression.

GoBonnieGo reads the files concurrently in 64 kiB chunks. Every 127 chunks it does a byte comparison against the original random data 64 kiB chunk to make sure there has been no corruption. This probably exacts a small penalty in read performance.

For IOPS measurement, a GoBonnieGo thread seeks to a random position in the file and reads 512 bytes. This counts as a single operation. Every tenth seek instead of reading it will write 512 bytes of data. This also counts as an operation. The ratio of reads:writes is 10:1, in order to approximate the ratio that the TPC-E benchmark uses (

The IOPS measurement cycle runs for approximately 15 seconds, at the end of which GoBonnieGo tallies up the number of I/O operations and divides by the duration of the test.

GoBonnieGo uses ioutil.TempDir() to create the temporary directory in which to place its files, unless overridden by the -dir flag. On Linux systems this temporary directory is often /tmp/, on macOS systems, /var/folders/....

GoBonnieGo measures bytes in MiB and GiB:

  • 1 MiB == 220 bytes == 1,048,576 bytes
  • 1 GiB == 230 bytes == 1,073,741,824 bytes

However, the output of the read and write metrics are in MB/s (Megabytes/second, i.e. 1,000,000 bytes per second) to conform with the industry norm.

GoBonnieGo uses 64 kiB blocks for its read and write tests. For its IOPS test, it uses a 512-byte blocks: it seeks to a random location in the test file and either reads or writes 512 bytes.


GoBonnieGo may have difficulty running on 32-bit systems; int and int64 were used interchangeably in the code.

If GoBonnieGo crashes you may need to find and delete the GoBonnieGo files manually. Below is a sample find command to locate the GoBonnieGo directory; delete that directory and everything underneath:

find / -name gobonniegoParent\* -follow

GoBonnieGo needs integration tests. Badly.


Tim Bray wrote the original bonnie which inspired Russell Coker to write bonnie++ which was used to measure ZFS performance in's post which inspired me to build a ZFS-based NAS and benchmark it. And credit must be given to Brendan Gregg's excellent post, Active Benchmarking: Bonnie++.


Tim Bray suggested the name, gobonniego:

maybe "GoBonnieGo"?

It's a reference to the refrain of Chuck Berry's song, Johnny B. Goode, which repeats the phrase, "Go Johnny go"


The impetus for writing GoBonnieGo is to provide concurrency. During a benchmark of a ZFS filesystem (using bonnie++), it became clear that a the single-threaded performance of bonnie++ and not disk speed was the limiting factor.

You can’t perform that action at this time.