Sections of this module:Introduction
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In this module we will discuss how you can back up your instance and your data. You will learn how to make snapshots and how to recover your virtual machine using this snapshot. You will also learn how to terminate your virtual machine and release your storage without losing anything.
Is is important to be aware of the measures taken by NeCTAR to prevent data loss. But an important part of keeping your data safe is your responsibility: You should create backups at regular intervals. In this module, you will learn several approaches to backing up your data.
Another very important activity is “cleaning up” your resources after you have finished using them. This involves not only securely erasing data on your volumes or ephemeral storage. You should also “terminate” (delete) your instance and your storage as soon as you don’t need it any more. Why is this so important? Because your running instance and your existing storage take up resources which other researchers may need.
NeCTAR experiences resource shortages from time to time, which could be avoided if unused (idle) or underutilised (mostly idle) NeCTAR instances were shut down, freeing up resources. It has been observed that the average CPU utilization rate across the NeCTAR federation is less than 5%, and many large instances sit idle for days, weeks or months at a time.
The problem is that many people want their compute resources to be available when they are ready to use them. They don’t realise that while they are not using those resources, they are preventing others from accessing them. It is therefore important that everyone is aware of this and responsibly releases their resources when they don’t need them any more. Fair play!
The amount of CPU hours you request in an allocation is the amount of time your instance will be in existence — not the time the CPU is actually busy with your programs! That is, all time counts between when you launch the instance and terminate it — regardless whether the CPU is idle the whole time, or the instance is shut down or suspended. While you have access to the instance, it counts as CPU hours!
Consider this also when you plan on how to use your instance — you can back up the state of your instance and then “terminate” it while you don’t need it. It will be easy to restore it to the exact same state when you need it again.
It is not difficult to save your instance and volumes (“create a snapshot”), then terminate the instance and release the volumes, and re-launch your instance and volumes in exactly the same state at a later time, when you need it. In this module, we will show you how you can do this.
The following videos go through most of the content in this module and offer a less in-depth description of the subject than the documentation does.
The notation throughout the training documents can be interpreted as follows:
Words in italics are used for names and terminology, e.g. name of a software, or name of a computing concept. It may also just emphasise a word in the traditional way. Quotations are also written in italics and are put in between quotatioin marks.
Words in bold are used to highlight words which identify important concepts of a paragraph, to make it easier for users to skim through the text to find a paragraph which explains a certain idea, concept or technology.
Additional information which is optional to read is displayed in info boxes like this one.
Important information is displayed in boxes like this one.
Definition of terms are displayed in boxes of this style.
Possibly specific prerequisites for reading a particular section are contained in this type of box at the beginning of a section.
The use of command line tools is part of this course. In a Terminal, you will be directed to type in commands. Commands are formatted as follows:
command-name argument1 argument2 ... argumentn
Throughout the exercises, when you see a word in pointed brackets, like <this-word>, it means that you have to replace everything inside the brackets, and including the brackets, with whatever is described within the brackets.
For example, if you are prompted to run a command named the-command which takes two arguments:
the-command -f <yourfile>
Then you have to replace the second argument, <yourfile>, with the file name that is being referenced in the exercise. For example
the-command -f thefile.txt
When editing a file, the contents of it will be displayed in a different font and with background colour as follows:
The content of the file The next line in this file
Output on the command line terminal is printed in boxes formatted as follows:
NectarInstance:~ Jennifer$ whoami Jennifer