FAQ

Pause, Suspend, Shelve and Shut Off Instance. What’s the difference?

See Stopping an instance for the differences between the methods of halting a compute instance.

For lowering costs and long term preservation of compute instances, Shelve Instance is the recommended option.

The cost of a running instance vs a shelved instance

Note

It is important to be aware that the Shelve Instance action will only help to lower the monthly costs associated with your cloud project.

The act of shelving an instance creates a snapshot of the running instance which it stores as an image on block storage, meaning you now have an extra volume associated with your project. Once this has been done, it stops the instance and schedules it to be removed from memory. The cost saving when shelving instances is due to the fact that you are no longer paying for the compute services that a running instance uses. Instead, you are now only paying the much cheaper cost of storing a snapshot of your image on disk.

To illustrate this, let’s say you had a simple 1 vCPU 1Gb RAM instance with a 10GB disk running 24/7 for an entire month, which we will assume is 730 hours as an average.

The cost for this would be: $32.12 / month

Compare that to the same instance stored as a disk image: $4.02 / month

You can see that even for such a small compute instance the cost saving is quite significant. If you were to apply this to a compute instance with 4vCPU and 16GB RAM, the monthly running cost would be: $285.43 / month

so it would definitely make sense to shelve instances you don’t need to run full time.

Locale errors on Ubuntu Linux

When launching an Ubuntu compute instance using the images provided by Canonical, we recommend you configure the locale using cloud-init. The example below illustrates how the locale can be defined at boot time using the cloud-config syntax.

#cloud-config
fqdn: instancename.example.com
locale: en_US.UTF-8

If the locale is not configured appropriately, you may get locale related errors, such as:

  • locale.Error: unsupported locale setting
  • perl: warning: Setting locale failed
  • perl: warning: Please check that your locale settings

These errors can occur while installing packages or performing simple tasks on the operating system.

If you have not defined the locale at boot time, you can still configure it later using the following procedure.

First, ensure that your hostname is defined in /etc/hosts (sudo vi /etc/hosts). If you only have an entry for localhost, add another entry with the name of your compute instance, as shown below:

127.0.0.1 localhost
127.0.0.1 instancename

Use the commands below to configure and generate your locales. Replace en_US.UTF-8 with your desired locale.

export LC_ALL="en_US.UTF-8"
sudo echo "LC_ALL=en_US.UTF-8" >> /etc/environment
sudo dpkg-reconfigure locales

How to SSH from Windows using PuTTY

This is intended as a quick guide for Windows users on how to create SSH keys and connect via SSH to Linux instances using PuTTY and PuTTYgen.

What is PuTTY

PuTTY is an open source SSH client, developed originally by Simon Tatham for the Windows platform.

This guide assumes that you have downloaded and installed the latest msi package which can be found here.

Once the package has been installed you should have access to 2 new applications, PuTTY which is the SSH client and PuTTygen which is the SSH key management tool.

Creating an SSH key

Launch the PuTTYgen application.

Set the Parameters as follows:

  • Type : RSA
  • Number of bits in generated key : 4096

Then click Generate

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Move the mouse around to generate enough entropy to create the key

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Once the key has been created, set a passphrase and save the private key and the public key. In this example we will save the private key as id_rsa.ppk

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Adding your SSH key to your project

Once you have successfully created your SSH key you need to import the public portion into your cloud project.

First highlight and copy ALL of the text in the Public key for pasting dialogue box. Ensure you scroll to the bottom to get everything.

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Next, log into the cloud dashboard, select Key Pairs from left hand menu and then Import Key Pair. Enter a meaningful name for the key and paste in the public key text from the previous step and Import Key Pair

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Once the key has been imported confirm that the fingerprint matches the one shown in PuTTYgen.

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Connecting with SSH and PuTTY

Once you have the new key in place in your cloud project you can launch a new instance providing this as the keypair for authentication. For the purpose of this example we will assume that the new instance is running Ubuntu.

Open PuTTY and navigate to Connection -> SSH -> Auth in the Category panel.

Configure the settings as shown below, any existing settings can be left as they are.

  • Allow attempted changes of username in SSH-2 : Checked
  • Private key file for authentication : enter the location of the private key that was saved in PuTTYgen earlier.
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In the Category panel switch to the session screen and enter the floating IP address of the cloud instance you wish to connect to and click Open.

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In the terminal session that appears enter the default username for the OS that you have deployed. As we have assumed that we are running an Ubuntu instance our username will be ubuntu.

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You will then be prompted to supply the passphrase that was used when creating the SSH key in PuTTYgen.

Note

If this is the first time that you have connected to this server you will also be asked to accept the servers host key. Say Yes to this.

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You should now be logged successfully into your instance.

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