Create Instance Offering

In the navigation pane of the ZStack Private Cloud UI, choose Resource Pool > Instance Offering. On the Instance Offering page, click Create Instance Offering. On the displayed Create Instance Offering page, set the following parameters:

Name: Enter a name for the instance offering.
Description: Optional. Enter a description for the instance offering.
CPU: Set the number of CPU cores.
Note: Currently, a VM instance can have up to 240 CPU cores. You can set the number of CPU cores as needed.
Memory: Set the memory size for your VM instance. Unit: MB | GB | TB.
Host Allocation Strategy: When you create a VM instance by using this instance offering, the system will allocate a host for the VM instance according to the corresponding host allocation strategy. Default strategy: Host with min. running VMs. Each strategy is described as follows:
- Host with min. running VMs: The host with the minimum number of running VM instances will be chosen to create VM instances.
- Host with min. CPU utilization: The host with the minimum CPU utilization will be chosen to create VM instances.
  Note:
  - The system collects the host CPU loads over a period of time, calculates the average CPU usage during this period, and then selects the host with the lowest CPU usage to create VM instances.
  - By default, the data collection cycle is 10 minutes. To change the collection cycle, go to Settings > Global Settings > Advanced, locate Minimum interval of Host collecting CPU usage, and click the Edit icon.
- Host with min. memory utilization: The host with the minimum memory utilization will be chosen to create VM instances.
  Note:
  - The system collects the host memory loads over a period of time, calculates the average memory usage during this period, and then selects the host with the lowest memory usage to create VM instances.
  - By default, the data collection cycle is 10 minutes. To change the collection cycle, go to Settings > Global Settings > Advanced, locate Minimum interval of Host collecting Memory usage, and click the Edit icon.
- Host with max. running VMs: The host with the maximum number of running VM instances will be chosen to create VM instances. To use this option, you need to set the maximum number of VM instances that can run on a host. Then, the system selects the host that meets the requirements to create VM instances. If no host is available, you will fail to create a VM instance.
- Host where the VM located last time: When you restart a stopped VM instance, the system selects the host where the VM was running last time. If you start a new VM instance for the first time, the system selects a host randomly.
- Random allocation: The system randomly selects a host to create VM instances.
Strategy Pattern: This parameter is required if you set the host allocation strategy to Host with min. CPU utilization or Host with min. memory utilization. Options: Allocation Strategy (soft) | Allocation Strategy (hard).
- If the cloud can query the host load information, the cloud creates VM instances according to the host allocation strategy.
- If the cloud cannot query the host load information, the cloud creates VM instances according to the strategy pattern.
  - Allocation strategy (soft): The cloud randomly allocates a host with sufficient resources to create VM instances without considering the host allocation strategy.
  - Allocation strategy (hard): The cloud uses the host allocation strategy forcibly, which might cause VM creation failure.
Disk Bandwidth: Optional. Set the upper limit of the root volume I/O bandwidth for a VM instance. If not specified, the I/O bandwidth is not limited. Unit: MB/s | GB/s | TB/s.
The disk bandwidth parameter has the following two options:
- Total:
  If you select Total, set the upper limit of the total read and write speed of the VM root volume. The value must be an integer. Unit: MB/s | GB/s. Value range: 1 MB/s–100 GB/s.
  As shown in Figure 1.
  Figure 1. Total Bandwidth
- Read/Write:
  If you select Read/Write, set the following parameters:
  - Volume Read Bandwidth: Set the upper limit of the read speed of the VM root volume. The value must be an integer. Unit: MB/s | GB/s. Value range: 1 MB/s–100 GB/s.
  - Volume Write Bandwidth: Set the upper limit of the write speed of the VM root volume. The value must be an integer. Unit: MB/s | GB/s. Value range: 1 MB/s–100 GB/s.
  As shown in Figure 2.
  Figure 2. Read/Write Bandwidth
Network Bandwidth: Set the upper limit of the VM network bandwidth. The value must be an integer. Unit: Kbps | Mbps | Gbps. Value range: 8 Kbps–100 Gbps.
- Upstream Bandwidth: Optional. Set the upper limit of the network bandwidth for uploading from a VM instance. If not specified, the upstream bandwidth is not limited. The value must be an integer. Unit: Kbps | Mbps | Gbps. Value range: 8 Kbps–100 Gbps.
- Downstream Bandwidth: Optional. Set the upper limit of the network bandwidth for downloading from a VM instance. If not specified, the downstream bandwidth is not limited. The value must be an integer. Unit: Kbps | Mbps | Gbps. Value range: 8 Kbps–100 Gbps.
Note: Before you make any settings, make sure that you fully understand the configurations of the disk bandwidth and network bandwidth. Otherwise, you might fail to upload files to or download files from a VM instance.
Advanced: You can configure advanced parameters in JSON format to customize the disk performance.
Sample:
```
{
  "allocate": {
    "primaryStorage": {
      "type": "Enter the primary storage type. Options: Ceph | LocalStorage | NFS | SharedBlock.",
      "uuid": "Enter the primary storage UUID.",
      "poolNames": [
        "Enter the name of the Ceph pool. If the primary storage type is not Ceph, delete the poolNames configuration."
      ]
    }
  },
  "priceUserConfig": {
    "rootVolume": {
      "priceKeyName": "Customize the billing name of the root volume. The advanced parameters of the pricing list must be consistent with this field. Otherwise, the related billing metrics cannot be generated."
    }
  },
  "displayAttribute": {
    "rootVolume": {
      "diskType": "Customize the display type of the root volume. This field is displayed on the details page of the VM instance."
    }
  }
}
```
The sample above contains three configurations:
1. Configure the primary storage of the root volume.
```
"allocate": {
    "primaryStorage": {
      "type": "Enter the primary storage type. Options: Ceph | LocalStorage | NFS | SharedBlock.",
      "uuid": "Enter the primary storage UUID.",
      "poolNames": [
        "Enter the name of the Ceph pool. If the primary storage type is not Ceph, delete the poolNames configuration."
      ]
    }
  }
```
  - type: Enter the primary storage type. Options: Ceph | LocalStorage | NFS | SharedBlock. If the type is Ceph, you can specify a Ceph pool.
  - uuid: Enter the primary storage UUID.
  - poolNames: Enter the name of the Ceph pool. If the primary storage type is not Ceph, delete the poolNames configuration.
  Note: If no primary storage is specified, delete all the preceding codes.
2. Configure the billing type of the root volume.
```
"priceUserConfig": {
    "rootVolume": {
      "priceKeyName": "Customize the billing type of the root volume. The advanced parameters of the pricing list must be consistent with this field. Otherwise, the related billing metrics cannot be generated."
    }
  }
```
  - priceKeyName: Customize the billing type of the root volume. The advanced parameters of the pricing list must be consistent with this field. Otherwise, the related billing metrics cannot be generated.
  Note: If no billing is required, delete all the preceding codes.
3. Configure the display attributes of the root volume.
```
"displayAttribute": {
    "rootVolume": {
      "diskType": "Customize the display type of the root volume. This field is displayed on the details page of the VM instance and the root volume."
    }
  }
```
  - rootVolume: Customize the display name of the root volume. This field is used for display on the details page. You can configure multiple attributes in the key-value format.
  Note: If no special display is required, delete all the preceding codes.

As shown in Figure 3. Click OK to finish creating the instance offering.