Getting started - deploying a Parallel Virtual Cluster

PVC aims to be easy to deploy, letting you get on with managing your cluster in just a few hours at most. Once initial setup is complete, the cluster is managed via the clients, though the Ansible framework is used to add, remove, or modify nodes as required.

This guide will walk you through setting up a simple 3-node PVC cluster from scratch, ending with a fully-usable cluster ready to provision virtual machines. Note that all domains, IP addresses, etc. used are examples - when following this guide, be sure to modify the commands and configurations to suit your needs.

Part One - Preparing for bootstrap

  1. Read through the Cluster Architecture documentation. This documentation details the requirements and conventions of a PVC cluster, and is important to understand before proceeding.

  2. Download the latest copy of the pvc-ansible repository to your local machine.

  3. Leverage the script in the pvc-ansible directory to set up a local cluster configuration directory; follow the instructions the script provides, as all future steps will be done inside your new local configuration directory.

  4. Create an initial hosts inventory, using hosts.default in the pvc-ansible repo as a template. You can manage multiple PVC clusters ("sites") from the Ansible repository easily, however for simplicity you can use the simple name cluster for your initial site. Define the 3 hostnames you will use under the site group; usually the provided names of pvchv1, pvchv2, and pvchv3 are sufficient, though you may use any hostname pattern you wish. It is very important that the names all contain a sequential number, however, as this is used by various components.

  5. Create an initial set of group_vars for your cluster at group_vars/<cluster>, using the group_vars/default in the pvc-ansible repo as a template. Inside these group vars are two main files: base.yml and pvc.yml. These example files are well-documented; read them carefully and specify all required options before proceeding, and reference the Ansible manual for more detailed descriptions of the options.

    • base.yml configures the base role and some common per-cluster configurations such as an upstream domain, a root password, a set of administrative users, various hardware configuration items, as well as and most importantly, the basic network configuration of the nodes. Make special note of the various items that must be generated such as passwords; these should all be cluster-unique.

    • pvc.yml configures the pvc role, including all the dependent software and PVC itself. Important to note is the pvc_nodes list, which contains a list of all the nodes as well as per-node configurations for each. All nodes must be a part of this list.

  6. In the pvc-installer directory, run the script to generate an installer ISO. This script requires debootstrap, isolinux, and xorriso to function. The resulting file will, by default, be named pvc-installer_<date>.iso in the current directory. For additional options, use the -h flag to show help information for the script.

Part Two - Preparing and installing the physical hosts

  1. Prepare 3 physical servers with IPMI. The servers should match the specifications and requirements outlined in the Cluster Architecture documentation. Connect their networking based on the configuration set in the base.yml group vars file for your cluster.

  2. Load the installer ISO generated in step 6 of the previous section onto a USB stick, or using IPMI virtual media, on the physical servers.

  3. Boot the physical servers off of the installer ISO. Use UEFI mode - if available - for maximum flexibility and longevity.

  4. Follow the prompts from the installer ISO. It will ask for a hostname, the system disk device to use, the initial network interface to configure as well as vLANs and either DHCP or static IP information, and finally either an HTTP URL containing an SSH authorized_keys to use for the deploy user, or a password for this user if key auth is unavailable.

  5. Wait for the installer to complete. This may take several minutes.

  6. At the end of the install process, follow the prompts carefully; it is usually prudent to pre-see the /etc/network/interfaces configuration based on your expected final physical network config (e.g. set up bonding, etc.) before proceeding, especially if you use DHCP, as the bonding configuration applied later could affect the address. The chroot is likely unneeded unless you have good reason to edit the system in this way.

  7. Make note of the (temporary and insecure!) root password set by the installer; you may need it to troubleshoot the system if it does not come up properly. This will be overwritten later in the setup process.

  8. Press "Enter" to reboot the system and confirm it is reachable.

  9. Repeat the above steps for all 3 initial nodes. On boot, they will display their configured IP address to be used in the next steps.

Part Three - Initial bootstrap with Ansible

  1. Make note of the IP addresses of all 3 initial nodes, and configure DNS, /etc/hosts, or Ansible ansible_host= hostvars to map these IP addresses to the hostnames set in the Ansible hosts and group_vars files.

  2. Verify connectivity from your administrative host to the 3 initial nodes, including SSH access as the deploy user. Accept their host keys as required before proceeding as Ansible does not like those prompts. If you did not configure SSH key auth during the PVC installer process, configure it now, as it greatly simplifies Ansible configuration.

  3. Verify your group_vars setup from part 1, as errors here may require a re-installation and restart of the bootstrap process.

  4. Perform the initial bootstrap. From your local configuration repository directory, execute the following ansible-playbook command, replacing <cluster_name> with the Ansible group name from the hosts file. Make special note of the additional bootstrap=yes variable, which tells the playbook that this is an initial bootstrap run.
    $ ansible-playbook -v -i hosts pvc.yml -l <cluster_name> -e bootstrap=yes

    WARNING: Never run this playbook with the -e bootstrap=yes option against an active, already-bootstrapped cluster. This will have disastrous consequences including the loss of all data in the Ceph system as well as any configured networks, VMs, etc.

  5. Wait for the Ansible playbook run to finish. Once completed, the cluster bootstrap will be finished, and all 3 nodes will have rebooted into a working PVC cluster. If any errors occur, carefully evaluate them and re-run the playbook (with -o bootstrap=yes - your cluster is not active yet!) as required.

  6. Download and install the CLI client package (pvc-client-cli.deb) on your administrative host, and add and verify connectivity to the cluster; this will also verify that the API is working. You will need to know the cluster upstream floating IP address you configured in the networks section of the base.yml playbook, and if you configured SSL or authentication for the API in your group_vars, adjust the first command as needed (see pvc cluster add -h for details). A human-readable description can also be specified, which is useful if you manage multiple clusters and their names become unweildy.
    $ pvc cluster add -a <upstream_floating_ip> -d "My first PVC cluster" mycluster
    $ pvc -c mycluster node list

    You can also set a default cluster by exporting the PVC_CLUSTER environment variable to avoid requiring -c cluster with every subsequent command:
    $ export PVC_CLUSTER="mycluster"

    Note: It is fully possible to administer the cluster from the nodes themselves via SSH should you so choose, to avoid requiring the PVC client on your local machine.

Part Four - Configuring the Ceph storage cluster

  1. Determine the Ceph OSD block devices on each host via an ssh shell. For instance, use lsblk or check /dev/disk/by-path to show the block devices by their physical SAS/SATA bus location, and obtain the relevant /dev/sdX name for each disk you wish to be a Ceph OSD on each host.

  2. Cofigure an OSD device for each data disk in each host. The general command is:
    $ pvc storage osd add --weight <weight> <node> <device>

    For example, if each node has two data disks, as /dev/sdb and /dev/sdc, run the commands as follows to add the first disk to each node, then the second disk to each node:
    $ pvc storage osd add --weight 1.0 pvchv1 /dev/sdb
    $ pvc storage osd add --weight 1.0 pvchv2 /dev/sdb
    $ pvc storage osd add --weight 1.0 pvchv3 /dev/sdb
    $ pvc storage osd add --weight 1.0 pvchv1 /dev/sdc
    $ pvc storage osd add --weight 1.0 pvchv2 /dev/sdc
    $ pvc storage osd add --weight 1.0 pvchv3 /dev/sdc

    NOTE: On the CLI, the --weight argument is optional, and defaults to 1.0. In the API, it must be specified explicitly, but the CLI sets a default value. OSD weights determine the relative amount of data which can fit onto each OSD. Under normal circumstances, you would want all OSDs to be of identical size, and hence all should have the same weight. If your OSDs are instead different sizes, the weight should be proportional to the size, e.g. 1.0 for a 100GB disk, 2.0 for a 200GB disk, etc. For more details, see the Cluster Architecture and Ceph documentation.

    NOTE: OSD commands wait for the action to complete on the node, and can take some time (up to 30 seconds).

    NOTE: You can add OSDs in any order you wish, for instance you can add the first OSD to each node and then add the second to each node, or you can add all nodes' OSDs together at once like the example. This ordering does not affect the cluster in any way.

  3. Verify that the OSDs were added and are functional (up and in):
    $ pvc storage osd list

  4. Create an RBD pool to store VM images on. The general command is:
    $ pvc storage pool add <name> <placement_groups>

    NOTE: Ceph placement groups are a complex topic; as a general rule it's easier to grow than shrink, so start small and grow as your cluster grows. The following are some good starting numbers for 3-node clusters, though the Ceph documentation and the Ceph placement group calculator are advisable for anything more complex. There is a trade-off between CPU usage and the number of total PGs for all pools in the cluster, with more PGs meaning more CPU usage.

    • 3 OSDs total: 128 PGs (1 pool) or 64 PGs (2 or more pools, each)
    • 6 OSDs total: 256 PGs (1 pool) or 128 PGs (2 or more pools, each)
    • 9+ OSDs total: 256 PGs

    For example, to create a pool named vms with 256 placement groups, run the command as follows:
    $ pvc storage pool add vms 256

    NOTE: As detailed in the cluster architecture documentation, you can also set a custom replica configuration for each pool if the default of 3 replica copies with 2 minimum copies is not acceptable. See pvc storage pool add -h or that document for full details.

  5. Verify that the pool was added:
    $ pvc storage pool list

Part Five - Creating virtual networks

  1. Determine a domain name and IPv4, and/or IPv6 network for your first client network, and any other client networks you may wish to create. These networks must not overlap with the cluster networks. For full details on the client network types, see the cluster architecture documentation.

  2. Create the virtual network. There are many options here, so see pvc network add -h for details.

    For example, to create the managed (EVPN VXLAN) network 100 with subnet, gateway .1 and DHCP from .100 to .199, run the command as follows:
    $ pvc network add 100 --type managed --description my-managed-network --domain myhosts.local --ipnet --gateway --dhcp --dhcp-start --dhcp-end

    For another example, to create the static bridged (switch-configured, tagged VLAN, with no PVC management of IPs) network 200, run the command as follows:
    $ pvc network add 200 --type bridged --description my-bridged-network

    NOTE: Network descriptions cannot contain spaces or special characters; keep them short, sweet, and dash or underscore delimited.

  3. Verify that the network(s) were added:
    $ pvc network list

  4. On the upstream router, configure one of:

    a) A BGP neighbour relationship with the cluster upstream floating address to automatically learn routes.

    b) Static routes for the configured client IP networks towards the cluster upstream floating address.

  5. On the upstream router, if required, configure NAT for the configured client IP networks.

  6. Verify the client networks are reachable by pinging the managed gateway from outside the cluster.

You're Done!

  1. Set all 3 nodes to ready state, allowing them to run virtual machines. The general command is:
    $ pvc node ready <node>

Congratulations, you now have a basic PVC storage cluster, ready to run your VMs.

For next steps, see the Provisioner manual for details on how to use the PVC provisioner to create new Virtual Machines, as well as the CLI manual and API manual for details on day-to-day usage of PVC.