Adding disks on the fly
by Uday R. Sawant, William Leemans, Jonathan Hobson, Oliver Pelz
Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Table of Contents
- Linux: Powerful Server Administration
- Linux: Powerful Server Administration
- Credits
- Preface
- 1. Module 1
- 1. Managing Users and Groups
- 2. Networking
- Introduction
- Connecting to a network with a static IP
- Installing the DHCP server
- Installing the DNS server
- Hiding behind the proxy with squid
- Being on time with NTP
- Discussing load balancing with HAProxy
- Tuning the TCP stack
- Troubleshooting network connectivity
- Securing remote access with OpenVPN
- Securing a network with uncomplicated firewall
- Securing against brute force attacks
- Discussing Ubuntu security best practices
- 3. Working with Web Servers
- Introduction
- Installing and configuring the Apache web server
- Serving dynamic contents with PHP
- Hosting multiple websites with a virtual domain
- Securing web traffic with HTTPS
- Installing Nginx with PHP_FPM
- Setting Nginx as a reverse proxy
- Load balancing with Nginx
- Setting HTTPs on Nginx
- Benchmarking and performance tuning of Apache
- Securing the web server
- Troubleshooting the web server
- 4. Working with Mail Servers
- 5. Handling Databases
- Introduction
- Installing relational databases with MySQL
- Storing and retrieving data with MySQL
- Importing and exporting bulk data
- Adding users and assigning access rights
- Installing web access for MySQL
- Setting backups
- Optimizing MySQL performance – queries
- Optimizing MySQL performance – configuration
- Creating MySQL replicas for scaling and high availability
- Troubleshooting MySQL
- Installing MongoDB
- Storing and retrieving data with MongoDB
- 6. Network Storage
- 7. Cloud Computing
- 8. Working with Containers
- Introduction
- Installing LXD, the Linux container daemon
- Deploying your first container with LXD
- Managing LXD containers
- Managing LXD containers – advanced options
- Setting resource limits on LXD containers
- Networking with LXD
- Installing Docker
- Starting and managing Docker containers
- Creating images with a Dockerfile
- Understanding Docker volumes
- Deploying WordPress using a Docker network
- Monitoring Docker containers
- Securing Docker containers
- 9. Streaming with Ampache
- 10. Communication Server with XMPP
- 11. Git Hosting
- Introduction
- Installing Git
- Creating a local repository with Git CLI
- Storing file revisions with Git commit
- Synchronizing the repository with a remote server
- Receiving updates with Git pull
- Creating repository clones
- Installing GitLab, your own Git hosting
- Adding users to the GitLab server
- Creating a repository with GitLab
- Automating common tasks with Git hooks
- 12. Collaboration Tools
- 13. Performance Monitoring
- 14. Centralized Authentication Service
- 2. Module 2
- 1. Installing CentOS
- Introduction
- Downloading CentOS and confirming the checksum on Windows or OS X
- Creating USB installation media on Windows or OS X
- Performing an installation of CentOS using the graphical installer
- Running a netinstall over HTTP
- Installing CentOS 7 using a kickstart file
- Getting started and customising the boot loader
- Troubleshooting the system in rescue mode
- Updating the installation and enhancing the minimal install with additional administration and development tools
- 2. Configuring the System
- Introduction
- Navigating text files with less
- Introduction to Vim
- Speaking the right language
- Synchronizing the system clock with NTP and the chrony suite
- Setting your hostname and resolving the network
- Building a static network connection
- Becoming a superuser
- Customizing your system banners and messages
- Priming the kernel
- 3. Managing the System
- Introduction
- Knowing and managing your background services
- Troubleshooting background services
- Tracking system resources with journald
- Configuring journald to make it persistent
- Managing users and their groups
- Scheduling tasks with cron
- Synchronizing files and doing more with rsync
- Maintaining backups and taking snapshots
- Monitoring important server infrastructure
- Taking control with GIT and Subversion
- 4. Managing Packages with YUM
- 5. Administering the Filesystem
- 6. Providing Security
- 7. Building a Network
- 8. Working with FTP
- 9. Working with Domains
- 10. Working with Databases
- 11. Providing Mail Services
- 12. Providing Web Services
- 13. Operating System-Level Virtualization
- 14. Working with SELinux
- 15. Monitoring IT Infrastructure
- 1. Installing CentOS
- 3. Module 3
- 1. Working with KVM Guests
- 2. Deploying RHEL "En Masse"
- 3. Configuring Your Network
- 4. Configuring Your New System
- 5. Using SELinux
- 6. Orchestrating with Ansible
- 7. Puppet Configuration Management
- 8. Yum and Repositories
- 9. Securing RHEL 7
- 10. Monitoring and Performance Tuning
- Bibliography
- Index
This recipe includes instructions on how to create different types of storage volumes. Storage volumes are dedicated storage sets aside for use by guests.
There is not a lot of preparation to be done in order to add disks to your guest, which is in contrast to adding CPUs and RAM.
You only need to ensure that the storage pool has enough free disk space to accommodate the new disk.
Similar to the recipe for creating guests, you'll need to create a disk first. This can be done as follows:
- Let's create a raw disk in the
localfs-vmpool that is30GB big through the following command:~]# virsh vol-create-as --pool localfs-vm --name rhel7_guest-vdb.raw --format raw --capacity 30G - Look up the path of the newly created volume, as follows:
~]# virsh vol-list --pool localfs-vm |awk '$1 ~ /^rhel7_guest-vdb.raw$/ {print $2}'This will result in the path of your volume; here's an example:
/vm/rhel7_guest-vdb.raw - Attach the disk to the guest, as follows:
~]# virsh attach-disk --domain <guestname> --source <the above path> --target vdb --cache none --persistent –live
Creating a disk using vol-create-as may take some time depending on the speed of your host's disks and the size of the guest's disks.
We will look up the path of the newly created volume as it is a required argument for the command that attaches the disk to the guest. In most cases, you won't need to do this as you'll know how your host is configured, but when you script this kind of functionality, you will require this step.
Adding a disk in this way will attach a disk using the virtio driver, which, as specified earlier, is optimized for use with KVMs.
If, for some reason, the original guest doesn't support virtio drivers or you do not have the virtio controller, you can create this yourself. Store the XML configuration file as /tmp/controller.xml with the following contents:
<controller type='scsi' model='virtio' />
You can find this out by checking the host's XML file for the preceding statement.
Then, import the XML configuration file, as follows:
~]# virsh attach-device –domain <guestname> /tmp/controller.xml
This will allow you to create disks using virtio.
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