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FAQs | Virtual Compute Service (VCS)

Connect to a VCS instance

Q1. What open source clients are available for connecting to TWSC resources, like CCS, VCS and HPC?

Third-party open source software such as MobaXterm, PuTTY and VSCode can be used.

Q2. I want to set up web services using VCS instance, but why can't I connect to the instance?

Please check whether the instance's security group or firewall rules block the connection. For related documents, refer to:

Q3. The VCS instance created from the image cannot be connected, what should I do?

Please check the following two configurations of the VCS instance before creating the image:

  1. If you set /etc/fstab to automatically mount the disk, please comment out this setting or add the nofail option, otherwise you will be unable to connect to the instance created by the image if cannot find the device.
  2. If you are using Ubuntu 18.04 instance, and you have changed the network configurations of /etc/network/interfaces, it will also cause the connection failure.

After checking the above two settings, create an image for the VCS instance again, and use the newly created image to create the VCS instance. If it still failed to connect, please describe the situation in detail and send an e-mail to isupport@twcc.ai, the Technical Support team will assist you to solve the problem.

Q4. What should I do if I can't connect to the instance after changing the network card settings?

After the network card settings are changed, it might cause a failure to connect to the VCS instance. Therefore, we strongly recommend you not to change the network card settings. Please be careful when operating and deploying.

If you can't connect to the instance, please describe the situation and VCS instance information in detail, and send an e-mail to isupport@twcc.ai, the Technical Support team will assist you to solve the problem.

Q5. How to speed up the SSH connection?

Please adjust the DNS settings of the VCS instance to make the SSH connection speed faster. The setting method and steps are as follows:

Step 1. Enter the command

sudo vi /etc/ssh/sshd_config

Step 2. Press i key to enter insert mode
Step 3. Add a line of command

Use DNS no

Step 4. Press esc key to exit insert mode, then enter :wq! to save the file.


If you still have a slow connection after the modification, please contact the Technical Support: isupport@twcc.ai, and provide your local IP and the result of the traceroute to the instance.

Q6. How to connect to the Linux instance using account and password?

Refer to this document to connect to the Linux instance using the account and password, which is a solution to losing key pairs or damaging files.

Q7. When connecting to the VCS instance using SSH, the error WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! occurs, what should I do?

The reason for this error is that the certificate stored on the local computer is different from the VCS instance. Therefore, you can avoid this error by deleting the certificate information of the local computer and regenerating it when connecting to the instance. Refer to the following command:

ssh-keygen  -f  "/Your_Path/.ssh/known_hosts"  -R  "Public IP"
Note:

Your_Path is the path of your local computer, and the following message will appear when you connect again:

Are you sure you want to continue connecting (yes/no)? Enter Yes to connect and generate a new certificate.

Q8. How to deal with macOS computers that can't connect to Linux devices?

Please go to the VCS Instance Details page , click the "Connect" button, and follow the instructions provided in the window to set the key pair access rights and SSH connection instance.

Q9. Is there a default password when I use Console to connect to a VCS instance?

There is no default password, you need to create a separate password before using Console to connect to the Linux instance, for Windows instances just enter the password you set when you created the instance, refer to Quick debugging and maintenance tools:TWSC VCS console

Manage VCS instances

Q1. What should I do if I fail to create the VCS instance?

Go to the VCS Instance Details page, hover to the Unsuccessful state, and it will display the creation failure message. Please take a screenshot of this page (and the creation failure message), together with the project ID and the VCS instance information (ID, image, hardware configuration, etc.) and send an e-mail to isupport@twcc.ai. Technical Support team will assist you to solve the problem.

Q2. What should I do if I forget the login password of the Windows VCS instance?

When creating a VCS instance, please be sure to save your password properly. If you forget the password, you can delete the instance and re-create it; if you need to save the data and configuration of the original instance, you can create an image of the instance first, and then create a new instance from the image and reset the password.

Q3. What should I do if I lose the key pair of the Linux VCS instance?

When creating a VCS instance, please be sure to keep your key pair properly. If you lose the key pair, you can delete the instance and re-create it; if you need to save the data and configuration of the original instance, you can create an image of the instance first, and then create a new instance from the image and use the new key pair.

Q4. What are the relationship between VCS instance states and the usage billing?
VCS instance stateInstance usage billing
StartingNot billed
ReadyBilled
StoppingBilled
ShutdownBilled
QueueingNot billed
DeletingBilled until the instance is successfully deleted
StoppedNot billed
ErrorNot billed

The instance will be billed in the Starting state if it is started from the Shutdown state.

Q5. In what state will the VCS instance not be billed?

The VCS instance will not be billed in the Queueing, Stopped and Error states, and it will be billed in other states. Whether the VCS instance in the Starting state be billed or not depends on the usage scenario. For detailed explanation, please refer to Q4.

Q6. How to solve the error message 440301: The request exceeded the quotas of ['floating_ip'] when creating a VCS instance?

The reason for this error message is that the number of floating ip's has reached the limit of the project, you can refer to the following practices.

  1. After deleting the floating IPs that the VCS instance does not need to use for now(the status of the instance is ready before it can be deleted), then select Create again.
  2. Floating IPs are released back into the pool after you stop or delete the instance and cannot be reclaimed. If you are using a fixed IP, we recommend that you subscribe and use a static IP.
  3. If you have special needs, please contact our customer service.

Resource allocation and monitoring

Q1. How to adjust the configurations of the created VCS instance?

If the configurations do not meet your requirements after creation and need to be adjusted to a smaller or larger instance, refer to HowTo: Resize VCS instances.

Q2. I have enough credit, but why I got The project is ran out of the resources and cannot create anymore. error when I was creating a VCS instance?

This message shows that your CPU usage has reached the project quota. We recommend you release CPU by creating images of the unused or less used VCS instances for future use, and delete the VCS instances.

Q3. How do I monitor the network traffic of my VCS instance?

On TWSC Portal, you can monitor the usage of CPU, disk, memory and network traffic with simple charts. You may install the monitoring program by yourself to get more detailed information.

Q4. How can I get GPU resources?

To efficiently allocate the frequently requested GPU resources, please email us your request at isupport@twcc.ai. We will have someone at your service.

Q5. How to convert available memory capacity (GB vs. GiB)?

If the available memory capacity is measured in GiB (1 GiB = 230 bytes), taking "vgv.xsuper" as an example, the available memory capacity is 84 GiB. Please see Memory capacity conversion for more information.

Q6. Why is there no GPU available after connecting to a VCS instance with GPU specifications?

The VCS instance with GPU specifications does not have GPU drivers installed by default. Please select and install the appropriate driver version that meets your environment's requirements. Detailed instructions can be found in this document.

Packages

Q1. Does Virtual Compute Service support SMTP?

In a VCS instance, you can install any software or applications for your needs, so you can set up and configure a SMTP server on a VCS instance to send e-mail.

Q2. When installing packages or updating the VCS instance, it shows E: Could not get lock /var/lib/apt/lists/lock. What should I do?
  1. When installing or updating the packages, there might be some error messages about the lock file. Please delete the lock file and try again.
  2. It is recommended to use Ubuntu 20.04 image to avoid this problem.
Q3. Why can't I select older operating systems that were previously available?

The images in TWSC VCS are sourced from officially released versions by the original developers. Generally, once a product ceases support or service, there will be no new security updates, non-security updates, or other service support, this is known as End of Service (EOS). When the original provider stops support or service, TWSC also ceases to update or support that version and discontinues its supply.

Q4. If a VCS instance has an End of Service (EOS) image, what impact does it have?

Existing instances will not be affected. Users can continue to use them, including connecting, stopping, starting, or rebooting. However, if a user deletes this instance, they won't be able to select the EOS image to create a new instance.

Q5. How can I update the OS of an existing VCS instance?
  1. Users can manually update the OS within the instance.
  2. Choose a new version of the image provided by TWSC, or upload a custom image to create a new instance.
Q6. Why can't the VCS instance of CentOS 7.9 perform package updates?

CentOS 7.9 officially reached its end of life (EOL) on June 30, 2024, which means it no longer supports package updates. It is recommended to use Rocky Linux to create a new VCS instance.

Storage and data transfer

Q1. Can Cloud Object Storage (COS) be mounted on VCS instances?

Yes, COS can be mounted on VCS instances. You have the full permission of the instance, so you can perform any operations on the instance. To mount COS using s3fs or related packages, refer to s3fs-fuse.

Q2. How to regularly back up VCS instance data to Cloud Object Storage (COS)?

Use TWCC-CLI and crontab -e to set up scheduled regular image creation.

Q3. What happens if an image over 100 GB is imported into a VCS instance?

The size of the system disk is 100GB. Though you won't be charged for the extra storage, the VCS instance won't be able to start if the system disk is used over 100GB.

Q4. How to download the VCS instance data to the local computer?

There are 2 methods you can use to download the instance data to your local machine:

  1. Using the Cloud Object Storage (COS). This method can not only achieve the purpose of data transmission, but also back up your instance:
  2. From your local machine, Use MobaXterm to connect to the VCS instance, and select "Sftp" icon on the left side to view, upload and download files.
Q5. How to upload the local data to the VCS instance?

There are 2 methods you can use to upload your local data to the VCS instance:

  1. Using Cloud Object Service (COS):
  2. From your local machine, Use MobaXterm to connect to the VCS instance, and select "Sftp" icon on the left side to view, upload and download files.

Network & Security

Elastic IP

Q1. Can I retrieve the public IP used by the VCS instance before it was stopped ?

After you stop the VCS instance, the floating IP will be released back to the resource pool and a new floating IP will be available after the individual starts.

If your usage scenario applies to fixed IPs, it is recommended that you subscribe and use static IPs. Please refer to Elastic IP to learn more.

Q2. Is it impossible to create a VCS instance after the number of default IPs available to the project has been exhausted?

You can continue to create VCS instances after the floating IP quota is used up, but you cannot configure floating IPs.If you need additional IPs, please subscribe for static IP. If you have special needs, please contact our customer service.

Please refer to Elastic IP Subscription Policy to learn more.

Q3. Why can't I subscribe to a static IP?

Please check your user status first. Only the Tenant Administrator can subscribe to static IPs and stop subscriptions in the project. If you have confirmed your administrator status and are still unable to subscribe, please contact Customer Service.

Q4. If I want to convert a floating IP bound to DNS to a static IP, is there a transition period for the conversion?

If the server (VCS instance) is hosting only one external service, you can first hook up a scheduled static IP to the load balancer and then forward the traffic from the load balancer to the back-end service server. After the DNS IP conversion is complete, then the static IP is hooked up to the server.

Virtual Network

Q1. Why can't the VCS instance connect to the Internet after creating?

Please check the virtual network configurations. If you have enabled the Basic Virtual Firewall (BVF), and you're not sure whether the rules are set correctly, we suggest you disable the firewall first and try to connect again. For Basic Virtual Firewall (BVF) configurations, refer to this document, or contact the Technical Support: isupport@twcc.ai.

Q2. How to open non-default open ports of the VCS instance to run services?
  • The default open ports of Linux instance: 22、443
  • The default open ports of Wondows instance: 22、443、9833
  • You may open an additional port by setting the security group, please refer to this document.

Q3. How to solve the error message 440301: The request exceeded the quotas of ['floating_ip'] when creating a VCS instance?

The reason for this error message is that the number of floating ip's has reached the limit of the project, you can refer to the following practices.

  1. After deleting the floating IPs that the VCS instance does not need to use for now(the status of the instance is ready before it can be deleted), then select Create again.
  2. If you have special needs, please contact our customer service.
Q4. Is there a limit to the speed of the network?

TWSC does not limit the speed of the network within the virtual computing entity. If you find that your transfer speeds are slow, we recommend that you take the following steps:

  1. Using the Network Speed Tool (e.g. Speedtest), then send the test results to the technical support email (isupport@twcc.ai) and we will determine if the speed is abnormal based on the information you provide.
  2. Confirm that the network speed of the source is not limited.
Q5. After adding a VNI to a VCS instance, can I use it immediately?

If you add the VNI while creating a VCS instance, after the instance is created, the VNI will be automatically enabled.

For existing VCS instances with specific OS image versions, after attaching the VNI, manual configuration is required to activate it.

Q6. Can two VCS instances within the same project connect with each other using private IP?

For two VCS instances within the same project to establish a direct connection using private IP without going through the external network, the following conditions must be met:

  1. Both VCS instances must have a VNI associated with the same virtual network (VNW).
  2. For security purposes, the security group ingress rules do not have all ports open to the public. Users need to modify the security group rules to allow mutual access between the two VCS instances.
Q7. How do I assign a private IP for a VCS instance?

Please refer to this document to create a VNI, where you can assign a private IP during the setup. When creating the instance, choose the option for an Independent VNI and select the VNI that has the private IP already configured.

Auto Scaling

Q1. How do I change the instance template that the auto scaling uses to scale out instances to meet my needs?

Please follow the steps:

  • Create a template image
  1. Create a VCS instance, deploy the environment and files, and create an instance image (or use your existing instance to create an image).
  2. Create a VCS instance from the image created in the Step 1.
  • Set up auto scaling
  1. Create an auto scaling.
  2. Attach the auto scaling to the instance created in Step 2. Follow the steps above, the auto scaling will use the template to scale out instances that meet your needs.

Images

Q1. How long does it take to create an image?

The image creation takes about 10-15 minutes.

Q2. How to shorten the image creation time?

If data transmitting while creating the image, the backup might be inconsistent, and the data might be saved incompletely; moreover, the backup process is longer than usual. Therefore, we suggest you shut down the instance manually (sudo shutdown) and make sure the data has been written into the virtual disks before creating an image.

Q3. How to automate the VCS image creation?

Use TWCC-CLI and crontab -e to set up scheduled regular image creation.

Q4. Why can't I share an image to another project?
  1. Only tenant administrators can share image to other target projects, and they must be tenant administrators of both the source and target projects.
  2. Cross-project sharing of licensed images is not supported (e.g. Windows servers with licenses).
  3. Customized image uploaded by yourself is not supported.
Q5. Why can't I select the GPU specification in the target project to create a VCS instance after the image of the GPU VM uses image sharing?

The image sharing function only supports the creation of CPU VCS instances in the target project, and does not support creating GPU VCS instances yet.

Q6. Why does the image status after sharing give an error?

If you share images generated from VCS instances created before 2021/3/27, such images will take too long to share and will fail due to unoptimized performance. For sharing requests, please contact technical support: isupport@twcc.ai.

Q7. Why can't I connect to a Linux instance created with an image?
Please use the following command to verify that the cloud-init package pre-installed in the image from the source entity has been removed: ```bash python3 -c "from cloudinit import log" ```
  • If the ModuleNotFoundError: No module named 'cloudinit' error message is returned, it means that the package has been deleted, which means that instances created from the image of that instance cannot be connected. Please create a new instance in TWSC, reinstall the required packages, and then create an image file for use and be careful not to delete the cloud-init package.
  • If you confirm that cloud-init has not been deleted, but you still cannot connect, please contact technical support: isupport@twcc.ai.
Q8. When using a customized image file to create custom instance, is there any limit to the system disk capacity?

You can only select a system disk capacity that is greater than or equal to the size of the image to create VM instance.

Q9. When uploading a custom image file, is there any limit to the image file size?

There is no size limit when uploading and creating a VCS customized image file. But currently TWSC only supports a maximum system disk of 500 GB, so it is recommended that the uploaded image not exceed 500 GB.

Q10. Can large-capacity system disk image be shared with other projects?

Currently, the image sharing function only supports 100 GB system disk. It is recommended that you first use a 100 GB system disk to create an image, share the image to the target project, and then use the image to create a VM with a larger system disk capacity instance.

Q11. Can the uploaded customized image be shared with other projects?

Currently, the customized image uploaded by users do not support image sharing function. If another project needs to use this image, please refer to Upload & create a custom image, upload this image to the designated project.

Q12. If the operating system of the customized image uploaded by myself is not Linux or Windows, how to set it?

When using a self-uploaded customized image to create a VM instance, the main purpose of selecting the operating system is to pre-set port 22 ssh connection (Linux) or port 9833 remote desktop connection (Windows). If there are other connection methods, you can choose one first, and then use console to connect to the instance for stetting. Please refer to TWSC VCS Console.

Q13. Can I create an image from the VM that created with customized image uploaded by myself?

Like a normal VMs, the VM created by the customized image file uploaded by user can create an image. Please refer to Create an image.

Q14. Why do customized image needs to be uploaded to Cloud Object Storage(COS) first?

In order to ensure the stable production of image for the system, TWSC VCS needs to use COS as an intermediary, and it is not allow to directly obtain personal customized image from external platforms or user's local hosts Reminder: Uploading image to COS will charge some fees. Please refer to Pricing.

Q15. How are customized images billed?

Customized images are billed based on the storage usage and the Virtual Disk Service (VDS) HDD type. When the image auto-backup feature is enabled on multiple VCS instances, it may generate a large number of images and take up substantial storage space, leading to considerable costs. Please be mindful and manage your images closely.

Q16. Do customized images include data disks?

A customized image includes system disks but does not include data disks.

Q17. How many image auto-backup copies can be created at most?

When the image auto-backup feature is enabled, the system will only retain the three most recent copies of the image for each instance. If a new image is created while the three quotas are filled, the system will automatically delete the oldest one.This limit does not apply to manually created images.

Q18. How to back up an image to my local machine?

Currently, TWCC does not support exporting images. If you need to back up data from a VCS instance, please use remote transfer tools to back up the files to your local machine.