Elastic Compute Service:Test the IOPS performance of an ESSD

Test conditions

• Sample operation: random write (randwrite).
• Image: We recommend that you use a later version of a Linux public image provided by Alibaba Cloud, such as CentOS 7.4 64-bit, CentOS 7.3 64-bit, CentOS 7.2 64-bit, or Alibaba Cloud Linux 2.1903 64-bit.
• Tool: We recommend that you use FIO.
• Instance type: We recommend that you use ecs.g7se.32xlarge. For more information, see g7se, storage-enhanced general-purpose instance family.
• ESSD: We recommend that you use an ESSD at performance level 3 (PL3 ESSD). In this example, the device name of the ESSD is /dev/your_device. Replace it with your actual device name. For more information, see ESSDs.

Operation notes

Procedure

1. Connect to an ECS instance.
   For more information, see Connect to a Linux instance by using a password.
2. Run the following commands in sequence to install libaio and FIO:

   sudo yum install libaio -y
   sudo yum install libaio-devel -y
   sudo yum install fio -y

3. Run the following command to switch the path:

   cd /tmp

4. Run the following command to create the test100w.sh script:

   vim test100w.sh

5. Paste the following content to the test100w.sh script.
   For more information, see Details about the test100w.sh script.

   function RunFio
   {
    numjobs=$1   # The number of test threads. In this example, the value is 10.
    iodepth=$2   # The maximum number of concurrent I/O requests. In this example, the value is 64.
    bs=$3        # The data block size per I/O. In this example, the value is 4k.
    rw=$4        # The read and write policy. In this example, the value is randwrite.
    size=$5
    filename=$6  # The name of the test file. In this example, the value is /dev/your_device.
    nr_cpus=`cat /proc/cpuinfo |grep "processor" |wc -l`
    if [ $nr_cpus -lt $numjobs ];then
        echo "Numjobs is more than cpu cores, exit!"
        exit -1
    fi
    let nu=$numjobs+1
    cpulist=""
    for ((i=1;i<10;i++))
    do
        list=`cat /sys/block/your_device/mq/*/cpu_list | awk '{if(i<=NF) print $i;}' i="$i" | tr -d ',' | tr '\n' ','`
        if [ -z $list ];then
            break
        fi
        cpulist=${cpulist}${list}
    done
    spincpu=`echo $cpulist | cut -d ',' -f 2-${nu}`
    echo $spincpu
    fio --ioengine=libaio --runtime=30s --numjobs=${numjobs} --iodepth=${iodepth} --bs=${bs} --size=${size} --rw=${rw} --filename=${filename} --time_based=1 --direct=1 --name=test --group_reporting --cpus_allowed=$spincpu --cpus_allowed_policy=split
   }
   echo 2 > /sys/block/your_device/queue/rq_affinity
   sleep 5
   RunFio 10 128 4k randwrite 1024g /dev/your_device

6. Modify the parameter settings in the test100w.sh script based on the actual conditions.
   • Replace your_device with the actual device name of the ESSD. Example: nvme1n1.
   • Modify 10, 64, 4k, randwrite, and /dev/your_device in RunFio 10 64 4k randwrite /dev/your_device based on the actual conditions.
   • To proceed with this operation, set filename to a device name. Example: [/dev/vdb]. If you do not want to risk data loss, set filename to a file path. Example: [/mnt/test.image].

   Warning

   • You can obtain accurate test results by testing raw disk partitions. However, you may destroy the file system structure in a raw disk partition if you directly test the partition. Before you test a raw disk, we recommend that you back up your data by taking a snapshot of the disk. For more information, see Create a snapshot of a disk.
   • We recommend that you do not test a disk in which the operating system is located or a disk that stores important data. To prevent data loss, we recommend that you use a new Elastic Compute Service (ECS) instance that does not contain data for the test.
7. Run the following command to test the performance of the ESSD:

   sh test100w.sh

   If the IOPS=*** result is displayed in the command output, the performance stress test for the ESSD is complete.

Details about the test100w.sh script

• In the script, the following command sets the rq_affinity parameter to 2:

  echo 2 > /sys/block/your_device/queue/rq_affinity

  Value of rq_affinity	Description
  1	Indicates that the block device delivers received I/O completion events to the group of the vCPUs that submit the corresponding I/O requests. In scenarios where multiple threads run concurrently, I/O completion events may be delivered only to one vCPU and cause a performance bottleneck.
  2	Indicates that the block device delivers received I/O completion events to the vCPUs that submit the corresponding I/O requests. In scenarios where multiple threads run concurrently, each vCPU can deliver its maximum performance.

• The following command runs jobs to bind queues to different CPU cores:

  fio -ioengine=libaio -runtime=30s -numjobs=${numjobs} -iodepth=${iodepth} -bs=${bs} -rw=${rw} -filename=${filename} -time_based=1 -direct=1 -name=test -group_reporting -cpus_allowed=$spincpu -cpus_allowed_policy=split

  Note In normal mode, a device has a single request queue. This request queue becomes a performance bottleneck when multiple threads concurrently process I/O requests. In multi-queue mode, a device can have multiple request queues to process I/O requests and deliver the maximum backend storage performance. For example, assume that you have four I/O threads. To make full use of multi-queue mode and improve storage performance, you must bind these threads to the CPU cores that correspond to different request queues.

  Parameter	Description	Example
  numjobs	The number of I/O threads.	10
  /dev/your_device	The device name of the ESSD.	/dev/nvme1n1
  cpus_allowed_policy	The parameter provided by FIO to bind vCPUs. FIO provides the cpus_allowed_policy and cpus_allowed parameters to bind vCPUs.	split

  The preceding command runs jobs to bind queues to different CPU cores. These queues have different queue IDs. To view the ID of the CPU core to which a queue is bound, perform the following steps:

  • Run the ls /sys/block/your_device/mq/ command. In this command, replace your_device with your actual device name. Example: nvme1n1. This command returns the ID of the queue for an ESSD whose device name is in the /dev/vd* format.
  • Run the cat /sys/block/your_device/mq//cpu_list command. In this command, replace your_device with your actual device name. Example: nvme1n1. This command returns the ID of the CPU core to which the queue for an ESSD is bound. The device name of the ESSD is in the /dev/vd* format.