Help Center/ Dedicated Host/ Best Practices/ Best Practices for Purchasing DeHs
Updated on 2025-05-14 GMT+08:00

Best Practices for Purchasing DeHs

Scenarios

Dedicated Host (DeH) provides dedicated physical hosts. You can create ECSs on a DeH to enhance isolation, security, and performance of your ECSs.

If you have specific requirements for the ECS resources, such as the number of ECSs, number of vCPUs, and memory size, you can calculate the number of DeHs required by referring to this document and determine the optimal order of provisioning ECSs.

This section describes how to purchase c6_pro DeHs and provision 20 c6.large.4 ECSs and 4 c6.12xlarge.4 ECSs.

Process

Step

Description

Step 1: Obtain the ECS List

Collect statistics on the list of ECSs to be provisioned based on service requirements.

Step 2: Adjust the ECS Flavors

Adjust the ECSs to be provisioned based on the ECS flavors supported by the DeH flavor family.

Step 3: Calculate the Number of DeHs to Be Purchased

Calculate the number of DeHs to be purchased. The following solutions are supported:

  • Solution 1: Accurate calculation. Calculate the number of DeHs to be purchased based on the information about all ECSs to be purchased.

    This solution is suitable for buying a few ECSs with a few types of flavors. The calculation result of this solution is accurate.

  • Solution 2: Fuzzy calculation. Calculate the required resources using information about all ECSs to be purchased. Then, calculate the number of DeHs to purchase based on the average allocation rate.

    This solution is suitable for buying a large number of ECSs with various flavors. This solution may be inaccurate because it uses the average allocation rate as a reference.

Step 4: Provision ECSs

Provision ECSs on the purchased DeHs.

Step 1: Obtain the ECS List

List the ECSs to be provisioned. As shown in Table 1, 20 ECSs (each with 2 vCPUs and 8 GiB of memory) and 4 ECSs (each with 48 vCPUs and 192 GiB of memory) need to be provisioned.

Table 1 ECS resources to be provisioned

vCPUs

Memory (GiB)

ECSs

2

8

20

48

192

4

Step 2: Adjust the ECS Flavors

Adjust the ECS flavors in the ECS list to those supported by the DeH flavor family.

For details, see ECSs Allowed on DeHs.

Step 3: Calculate the Number of DeHs to Be Purchased

Solution 1: Accurate calculation

Calculate the number of DeHs to be purchased based on the information about all ECSs to be purchased. This solution is suitable for provisioning a few ECSs with a few types of flavors.

Before the calculation, view the DeH flavor information and the NUMA topology information about the supported ECS flavors. For details, see Categories and Types.

The accurate calculation procedure is as follows:
  1. Sort the ECSs to be provisioned in descending order of flavors.

    For example, 20 ECSs of the c6.large.4 flavor and 4 ECSs of the c6.12xlarge.4 flavor need to be provisioned, as shown in Table 2.

    Table 2 ECS list

    vCPUs

    Memory (GiB)

    NUMA Nodes

    Required ECSs

    ECSs Already Provisioned

    48

    192

    2

    4

    0

    2

    8

    1

    20

    0

  2. Prepare an editable table and add one DeH to the initial resource pool.

    For example, if the selected DeH flavor is c6_pro, the initial resource pool information is shown in Table 3.

    Table 3 Initial resource pool

    DeH Name

    NUMA Information

    Resource Type

    Total Resources

    Used Resources

    Available Resources

    DeH1

    NUMA 0

    vCPUs

    36

    0

    36

    Memory (GiB)

    144

    0

    144

    NUMA 1

    vCPUs

    38

    0

    38

    Memory (GiB)

    152

    0

    152

  3. Obtain the first resource in the first row from the ECSs to be purchased in Table 2.

    Based on Table 2, calculate the resources as follows:

    • Required ECSs: Decrease by 1.
    • ECSs already provisioned: Increase by 1.

    Based on Table 3, calculate the resources as follows:

    • Used resources: Enter the vCPUs and memory of the resources by NUMA based on Table 2.
    • Available resources: Total resources – Used resources

    For example, after calculation, one ECS can be provisioned and is deducted from the required resources in the table. Table 4 shows the ECS list after resource deduction, and Table 5 shows the resource pool after calculation.

    Table 4 ECS list after calculation (deducting one ECS)

    vCPUs

    Memory (GiB)

    NUMA Nodes

    Required ECSs

    ECSs Already Provisioned

    48

    192

    2

    3

    1

    2

    8

    1

    20

    0

    Table 5 Resource pool after calculation (deducting one ECS)

    DeH Name

    NUMA Information

    Resource Type

    Total Resources

    Used Resources

    Available Resources

    DeH1

    NUMA 0

    vCPUs

    36

    24

    12

    Memory (GiB)

    144

    96

    48

    NUMA 1

    vCPUs

    38

    24

    14

    Memory (GiB)

    152

    96

    56

  4. Based on the DeH resource pool information, calculate the resources in Table 2 in sequence and check whether the DeH can provision an ECS.

    Check the topology information of the ECSs and DeH. If the vCPUs and memory in the DeH resource pool are greater than those of the ECS, the ECS can be provisioned.

    • If yes, deduct the provisioned ECS and repeat 3.

      If no required resources are available in the row where the resource to be purchased is located, select the next row of resources to be purchased and continue the calculation. If there is no next row, the calculation is complete.

    • If no, go to step 5.
  5. Add one DeH to the resource pool and repeat the operation in step 3.
    Table 6 Resource pool (one DeH added)

    DeH Name

    NUMA Information

    Resource Type

    Total Resources

    Used Resources

    Available Resources

    DeH1

    NUMA 0

    vCPUs

    36

    24

    12

    Memory (GiB)

    144

    96

    48

    NUMA 1

    vCPUs

    38

    24

    14

    Memory (GiB)

    152

    96

    56

    DeH2

    NUMA 0

    vCPUs

    36

    0

    36

    Memory (GiB)

    144

    0

    144

    NUMA 1

    vCPUs

    38

    0

    38

    Memory (GiB)

    152

    0

    152

  6. Repeat steps 3 to 5 until all resources in Table 2 are provisioned, that is, no required resources are available in all rows.
    According to the calculation, you need to purchase four DeHs of the c6_pro flavor to provision 20 ECSs of the c6.large.4 flavor and four ECSs of the c6.12xlarge.4 flavor.
    Table 7 ECS list (after purchase)

    vCPUs

    Memory (GiB)

    NUMA Nodes

    Required ECSs

    ECSs Already Provisioned

    48

    192

    2

    0

    4

    2

    8

    1

    0

    20

    Table 8 Resource pool (after purchase)

    DeH Name

    NUMA Information

    Resource Type

    Total Resources

    Used Resources

    Available Resources

    DeH1

    NUMA 0

    vCPUs

    36

    36

    0

    Memory (GiB)

    144

    144

    20

    NUMA 1

    vCPUs

    38

    38

    0

    Memory (GiB)

    152

    152

    12

    DeH2

    NUMA 0

    vCPUs

    36

    36

    0

    Memory (GiB)

    144

    144

    20

    NUMA 1

    vCPUs

    38

    26

    12

    Memory (GiB)

    152

    104

    48

    DeH3

    NUMA 0

    vCPUs

    36

    24

    12

    Memory (GiB)

    144

    96

    48

    NUMA 1

    vCPUs

    38

    24

    14

    Memory (GiB)

    152

    96

    56

    DeH4

    NUMA 0

    vCPUs

    36

    24

    12

    Memory (GiB)

    144

    96

    48

    NUMA 1

    vCPUs

    38

    24

    14

    Memory (GiB)

    152

    96

    56

Solution 2: Fuzzy calculation

Calculate the required resources using information about all ECSs to be purchased. Then, calculate the number of DeHs to purchase based on the average allocation rate. This solution is suitable for buying a large number of ECSs with various flavors. This solution may be inaccurate because it uses the average allocation rate as a reference.

  1. Collect resource information of all ECSs to be purchased and calculate the total number of vCPUs and memory capacity.
  2. Divide the total memory capacity by the total number of vCPUs to obtain the memory-to-vCPU ratio. Compare the ratio with that of DeHs. If the ratio is higher than that of DeHs, the memory is used for calculation. Otherwise, the vCPUs are used for calculation.
  3. Use the experience-based allocation rate as the standard rate to purchase DeHs.
    Table 9 Allocation rate (experience-based)

    Average vCPUs of Resources to Be Provisioned

    Average Allocation Rate

    < 32 vCPUs

    85%

    ≥ 32 vCPUs

    70%

  4. Calculate the number of DeHs to be purchased based on the following formula:

    Number of DeHs to be purchased = Ceiling (Total resources/Number of resources per DeH/Average allocation rate)

Step 4: Provision ECSs

Recommended provisioning sequence:

To provision as many ECSs as possible, you are advised to provision ECSs in descending order of flavors, which means provisioning large-specification ECSs first and then small-specification ECSs.

For details about how to provision ECSs on a DeH, see Deploying ECSs on DeHs.