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Troubleshooting

Test SSD and RAM speed and on VPS

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What I really like about VPS providers these days is ability to spin up an instance, and test if it’s good by measuring hardware performance. I would then discard it or proceed with it on permanent basis based on performance level. All major cloud providers (DigitalOcean, Linode, Vultr VPS) allow you to test them with their per-hour billing model. And this is great!

But how do you test performance of a VPS in a reliable way?

First, sign up for any of the hosting providers mentioned. Next, create a new VPS with the lowest RAM amount available.

All the testing is done via SSH. Once you are logged in as root user, you can test the performance of disk, RAM, and CPU.

Test SSD Disk performance

With modern PHP frameworks (WordPress can be considered as one), consisting of hundreds of small PHP files, it is extremely important to run the server off an SSD drive. Many hosting providers advertise SSD in their plans. But you may still find your site running slow. Common reason? Yes, they lied to you and they actually installed a regular SATA drive. You can test SSD existence and speed by running a simple test:

dd if=/dev/zero of=sb-io-test bs=1M count=1k conv=fdatasync; rm -rf sb-io-test

This will show you the speed of accessing the drive. If you find the number below 150 MB/s, be certain that it is not an SSD drive. If it is below 50 MB/s, it is a SATA drive that is having problems.

Upon running the test on a few VPS providers, I found that Linode is the fastest provider with real SSD performance: 700 MB/sec.

Test CPU performance

Install SysBench utility. For example, on CentOS/RHEL system:

sudo yum -y install epel-release
sudo yum -y install sysbench

Run the actual test with:

sysbench cpu --threads=$(nproc) run

Look at “events per second”. The higher the better.

Test RAM performance

You can also use SysBench for testing RAM performance:

sysbench --test=memory --memory-total-size=1G run
  1. Luparu Nicu

    I have a vps that empty, only with the debian8 64 operating system consumes 0.8G of memory, is it normal?

    Reply
    • Danila Vershinin

      It depends on what services enabled at startup and what device drivers are in use.

      Reply
  2. Provas

    Hi Danila, very good post. My VPS server is constantly down because low memory status, ( 1GB available, but when executing ‘free’ command is always near to 0. or only few mb) . Do you know how to free memory with command line? is it possible with workbench? Thanks in advance

    Reply
    • Danila Vershinin

      Hi Private, you’d rather have to configure the server to not reach “out of memory” state. This is usually achieved through lowering PHP-FPM max_children setting, MySQL innodb buffer pool lowering, etc.

      Reply
  3. IT Blog

    Thank you for your great info, i have VPS from some company but i found that the speed is not high and is not low look at the result:
    dd if=/dev/zero of=/tmp/basezap.img bs=512 count=1000 oflag=dsync
    1000+0 records in
    1000+0 records out
    512000 bytes (512 kB) copied, 3.93107 s, 130 kB/s

    Time is 4s and speed is 130kB/s and they said to me this is SSD VPS….are this is true?

    Regards,

    Reply
    • Danila Vershinin

      Your test is “flawed”. You’re testing by writing to tmp, which is usually mounted to RAM. And only 512k of data wouldn’t be presentable. Use test as given in my post, and run in a directory where e.g. your site files are present.

      Reply
  4. sbabis

    Hello,
    i have 2 vps at contabo.
    The disk speed is 150MB / sec.
    It is ssd or not ?

    Reply
    • Danila Vershinin

      It is likely an SSD but the result is a clear case of how Contabo shares clients’ resources between VPS instances.
      The performance is like a regular drive, not SSD, due to sharing.
      Too many VPS machines on a single hardware instance – that’s why it’s cheap.

      Reply

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