---
title: "Test disk speed"
description: "You'll need to check the speed of your disks when you carry out your tests. Whether you want to compare the performance of different disks or just check if they"
url: https://docs.us.ovhcloud.com/en/storage-and-backup/block-storage/test-disk-speed
lang: en
---
> For AI agents: the complete documentation index is available at https://docs.us.ovhcloud.com/en/llms.txt, the full documentation bundle is available at https://docs.us.ovhcloud.com/en/llms-full.txt.

# Test disk speed

You'll need to check the speed of your disks when you carry out your tests. Whether you want to compare the performance of different disks or just check if they are satisfactory.

 

## Requirements

- A [Public Cloud Instance](https://us.ovhcloud.com/public-cloud/) in your OVHcloud account
- Administrative (sudo) access to your instance via SSH (Linux) or RDP (Windows)

 

## Instructions

### Install the test command

#### On Linux

The command that you need to test your disk speed is called `fio`, and is not installed on your server by default.
To install `fio`, run the following command:
```bash
apt install fio
```

#### On Windows

The command that you need to test your disk speed is called `fio`, and is not installed on your server by default.
To install `fio`, log in to your instance via RDP and download this binary: [Microsoft Windows binaries for fio](https://bsdio.com/fio/).

 

### Test your disk speed

#### On Linux

To test your disk speed, run the following command:

**Note:** Please note that you will need to modify the `--numjobs` argument to reflect the number of CPUs that your instance has.
You can retrieve a list of arguments and their functions directly from the [fio guide](https://github.com/axboe/fio/blob/master/HOWTO.rst).

```bash
fio --name=rand-write --ioengine=libaio --iodepth=32 --rw=randwrite --invalidate=1 --bsrange=4k:4k,4k:4k --size=512m --runtime=120 --time_based --do_verify=1 --direct=1 --group_reporting --numjobs=1
```

#### On Windows

To test your disk speed, run the following command:

**Note:** Please note that you will need to modify the `--numjobs` argument to reflect the number of CPUs that your instance has.
You can retrieve a list of arguments and their functions directly from the [fio guide](https://github.com/axboe/fio/blob/master/HOWTO.rst).

```
fio --name=rand-write --ioengine=windowsaio --iodepth=32 --rw=randwrite --invalidate=1 --bsrange=4k:4k,4k:4k --size=512m --runtime=120 --time_based --do_verify=1 --direct=1 --group_reporting --numjobs=1
```

 

### Analyze the data

#### On Linux

Once the test is finished, you will get a result similar to the following:
```
fio-3.37
Starting 1 process
Jobs: 1 (f=1): [w(1)][100.0%][w=156MiB/s][w=40.0k IOPS][eta 00m:00s]
rand-write: (groupid=0, jobs=1): err= 0: pid=2974: Sat Nov 16 03:21:07 2024
  write: IOPS=40.0k, BW=156MiB/s (164MB/s)(18.3GiB/120001msec); 0 zone resets
    slat (usec): min=2, max=812, avg= 4.65, stdev= 1.89
    clat (usec): min=53, max=12487, avg=794.13, stdev=75.55
     lat (usec): min=58, max=12492, avg=798.78, stdev=75.53
    clat percentiles (usec):
     |  1.00th=[  742],  5.00th=[  775], 10.00th=[  783], 20.00th=[  783],
     | 30.00th=[  791], 40.00th=[  791], 50.00th=[  799], 60.00th=[  799],
     | 70.00th=[  799], 80.00th=[  807], 90.00th=[  807], 95.00th=[  816],
     | 99.00th=[  840], 99.50th=[  857], 99.90th=[ 1037], 99.95th=[ 1434],
     | 99.99th=[ 4883]
   bw (  KiB/s): min=159904, max=191976, per=100.00%, avg=160265.41, stdev=2060.10, samples=239
   iops        : min=39976, max=47994, avg=40066.36, stdev=515.02, samples=239
  lat (usec)   : 100=0.01%, 250=0.07%, 500=0.30%, 750=0.94%, 1000=98.56%
  lat (msec)   : 2=0.10%, 4=0.01%, 10=0.01%, 20=0.01%
  cpu          : usr=7.37%, sys=20.48%, ctx=4614084, majf=0, minf=10
  IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=100.0%, >=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.1%, 64=0.0%, >=64=0.0%
     issued rwts: total=0,4803938,0,0 short=0,0,0,0 dropped=0,0,0,0
     latency   : target=0, window=0, percentile=100.00%, depth=32

Run status group 0 (all jobs):
  WRITE: bw=156MiB/s (164MB/s), 156MiB/s-156MiB/s (164MB/s-164MB/s), io=18.3GiB (19.7GB), run=120001-120001msec

Disk stats (read/write):
  sda: ios=0/4799786, merge=0/29, ticks=0/3797382, in_queue=3797385, util=74.39% 
```
The line we are interested in is the fifth, which contains the IOPS:
```
write: IOPS=40.0k, BW=156MiB/s (164MB/s)(18.3GiB/120001msec); 0 zone resets
```
We can see that the performance of the main disk is around 40.0k IOPS.

#### On Windows

Once the test is finished, you will get a result similar to the following:
```
fio-3.38
Starting 1 thread
rand-write: Laying out IO file (1 file / 512MiB)
Jobs: 1 (f=1): [w(1)][100.0%][w=156MiB/s][w=40.0k IOPS][eta 00m:00s]
rand-write: (groupid=0, jobs=1): err= 0: pid=6880: Thu Nov 14 08:57:53 2024
write: IOPS=39.4k, BW=154MiB/s (161MB/s)(18.0GiB/120001msec); 0 zone resets
slat (usec): min=5, max=542348, avg=15.35, stdev=251.51
clat (nsec): min=900, max=184132k, avg=663865.64, stdev=581569.23
lat (usec): min=65, max=544389, avg=679.22, stdev=632.99
clat percentiles (usec):
|  1.00th=[  182],  5.00th=[  273], 10.00th=[  330], 20.00th=[  437],
| 30.00th=[  537], 40.00th=[  619], 50.00th=[  676], 60.00th=[  725],
| 70.00th=[  766], 80.00th=[  807], 90.00th=[  881], 95.00th=[  979],
| 99.00th=[ 1418], 99.50th=[ 1975], 99.90th=[ 6259], 99.95th=[ 8094],
| 99.99th=[13435]
bw (  KiB/s): min=111952, max=183453, per=100.00%, avg=157817.69, stdev=10924.21, samples=201
iops        : min=27988, max=45863, avg=39454.11, stdev=2731.09, samples=201
lat (nsec)   : 1000=0.01%
lat (usec)   : 2=0.01%, 4=0.01%, 10=0.01%, 20=0.01%, 50=0.01%
lat (usec)   : 100=0.06%, 250=3.54%, 500=22.77%, 750=40.01%, 1000=29.12%
lat (msec)   : 2=3.98%, 4=0.29%, 10=0.17%, 20=0.02%, 50=0.01%
lat (msec)   : 250=0.01%
cpu          : usr=7.50%, sys=36.67%, ctx=0, majf=0, minf=0
IO depths    : 1=0.2%, 2=0.5%, 4=1.8%, 8=9.5%, 16=71.1%, 32=17.0%, >=64=0.0%
submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete  : 0=0.0%, 4=94.7%, 8=2.1%, 16=1.6%, 32=1.6%, 64=0.0%, >=64=0.0%
issued rwts: total=0,4726001,0,0 short=0,0,0,0 dropped=0,0,0,0
latency   : target=0, window=0, percentile=100.00%, depth=32

Run status group 0 (all jobs):
WRITE: bw=154MiB/s (161MB/s), 154MiB/s-154MiB/s (161MB/s-161MB/s), io=18.0GiB (19.4GB), run=120001-120001msec
```
The line we are interested in is the sixth, which contains the IOPS:
```
write: IOPS=39.4k, BW=154MiB/s (161MB/s)(18.0GiB/120001msec); 0 zone resets
```
We can see that the performance of the main disk is around 39.4k IOPS.

 

### Additional disk

#### On Linux

To test the speed of an additional disk, you will need to mount the disk with the following command:
```bash
cd /mnt/disk
```
 
#### Analyze the data:

The IOPS value will depend on the type of additional disk you use. In the example below, we ran the test on a High speed volume:
```
fio-3.37
Starting 1 process
Jobs: 1 (f=1): [w(1)][100.0%][w=11.9MiB/s][w=3054 IOPS][eta 00m:00s]
rand-write: (groupid=0, jobs=1): err= 0: pid=2946: Sat Nov 16 03:13:20 2024
  write: IOPS=3052, BW=11.9MiB/s (12.5MB/s)(1431MiB/120011msec); 0 zone resets
    slat (usec): min=2, max=8119, avg= 6.14, stdev=53.35
    clat (usec): min=114, max=20721, avg=10477.33, stdev=587.51
     lat (usec): min=117, max=20724, avg=10483.47, stdev=584.33
    clat percentiles (usec):
     |  1.00th=[ 9634],  5.00th=[10028], 10.00th=[10028], 20.00th=[10159],
     | 30.00th=[10159], 40.00th=[10290], 50.00th=[10290], 60.00th=[10421],
     | 70.00th=[10552], 80.00th=[11076], 90.00th=[11207], 95.00th=[11338],
     | 99.00th=[11469], 99.50th=[11469], 99.90th=[12780], 99.95th=[14877],
     | 99.99th=[17433]
   bw (  KiB/s): min=12160, max=14648, per=100.00%, avg=12217.46, stdev=158.45, samples=239
   iops        : min= 3040, max= 3662, avg=3054.36, stdev=39.61, samples=239
  lat (usec)   : 250=0.01%, 500=0.04%, 750=0.03%, 1000=0.01%
  lat (msec)   : 2=0.01%, 4=0.01%, 10=5.06%, 20=94.84%, 50=0.01%
  cpu          : usr=0.70%, sys=1.82%, ctx=143740, majf=0, minf=10
  IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=100.0%, >=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.1%, 64=0.0%, >=64=0.0%
     issued rwts: total=0,366290,0,0 short=0,0,0,0 dropped=0,0,0,0
     latency   : target=0, window=0, percentile=100.00%, depth=32

Run status group 0 (all jobs):
  WRITE: bw=11.9MiB/s (12.5MB/s), 11.9MiB/s-11.9MiB/s (12.5MB/s-12.5MB/s), io=1431MiB (1500MB), run=120011-120011msec

Disk stats (read/write):
  sdb: ios=0/365996, merge=0/23, ticks=0/3826413, in_queue=3826472, util=96.45%
```
```
write: IOPS=3052, BW=11.9MiB/s (12.5MB/s)(1431MiB/120011msec); 0 zone resets
```
We can see that the performance of the additional disk is around 3052 IOPS.

##### On Windows

To test the speed of an additional disk, you will need to mount the disk. For more information, consult this [guide](https://docs.us.ovhcloud.com/en/storage-and-backup/block-storage/create-and-configure-an-additional-disk-on-an-instance.md).
Next, access the disk via PowerShell and run the same command as above.

 

## Go further

Browse all the [Block Storage guides](https://docs.us.ovhcloud.com/en/storage-and-backup/block-storage/landing-page-block-storage.md).

Browse the rest of the [OVHcloud US documentation](https://docs.us.ovhcloud.com/en/index.md) for guides on our other products and services.

Learn more about [Block Storage](https://us.ovhcloud.com/public-cloud/block-storage/) on the OVHcloud US website.