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The main Pstorage features are listed below:
* High performance - comparable to SAN.
See a brief [http://www.youtube.com/watch?v=6oEzW9w-1rg video on YouTube].
<span style="color:#FF0000">Parallels Cloud Storage is available as a TECHNOLOGY PREVIEW ONLY for OpenVZ users and can't be licensed for production.<br>To unlock for running in production you should upgrade to a full Parallels Cloud Server product (see below).<br>Maximum capacity limited for usage in technology preview mode is 100GB of logical (Containers usable) disk space.<br>After hitting this limit writers can get blocked w/o errors expecting for a limit to be extended, so please avoid hitting the limit (it's not a bug :) ).</span>
==Pstorage components=Components ===
Any Pstorage includes three components:
* Metadata server (MDS). MDSs manage metadata, like file names, and keep control over how files are split into chunks and where the chunks are stored. They also track versions of chunks and ensure that the cluster has enough replicas. An MDS can be run in multiple instances to provide high availability. Besides, MDSs keep a global log of important events that happen in the cluster.
* Chunk server (CS). A CS is a service responsible for storing real user data chunks and providing access to these data. A Pstorage cluster must have multiple instances of CSs for high availability.
* Clients. Clients access a Pstorage cluster by communicating with MDSs and CSs. Parallels Containers and virtual machines can be run natively, i.e. directly from the Pstorage cluster. An additional Pstorage client - can be used to mount Pstorage as a conventional file system (though Pstorage is not POSIX-compliant). Besides, Pstorage files can be mounted as a block device using the "ploop" feature and formatted as ext4 file system for other needs.
A recommended cluster setup includes from 3 to 5 MDS instances (allowing you to survive the loss of 1 or 2 of MDSs, respectively) and multiple CSs providing storage capacity.
== Setup ==
===Installing Parallels Cloud Storage software===
In order to install Pstorage RPM packages log in as root to all the machines planned to be added to the cluster and perform the following actions.
yum install pstorage-ctl pstorage-libs-shared pstorage-metadata-server pstorage-chunk-server pstorage-client
===Creating a cluster===
Every Pstorage cluster has a unique cluster name used for remote service discovery and during authorization.
So choose a name for the cluster that will uniquely identify it among other clusters in your network and avoid reusing it on cluster recreate. A name may contain the characters a-z, A-Z, 0-9, dash (-), and underscore (_). Here we will use 'test_cluster' as a cluster name.
====Create metadata servers (MDS)====
Log in to the computers you want to configure as a metadata server as root.
chkconfig pstorage-mdsd on
To create a 2nd and subsequent MDS services on other nodes , dothe following:
1. Login to the node as root.
pstorage -c test_cluster make-mds -a 10.30.100.102 -r /pstorage/test_cluster-mds
====Create a chunk server (CS)====
Log in to the computer you want to configure as a chunk server as root.
The command will ask you the password that you specified when setting up the first MDS server.
Create a CS:
pstorage -c test_cluster make-cs -r /pstorage/test_cluster-cs
chkconfig pstorage-csd on
====Setting up a client====
Log in to the computer you want to act as a client as root.
Now you can access your data from all the client machines and ready to run containers!
====Create a container running in the cluster====
Running a container over Pstrage is no different from any other local file system, so below example is just for the reference.
Create a ploop-based container with CTID=101 (put your own template name below):
vzctl create 101 --layout ploop --ostemplate centos-6-x86_64 --private /pcs/containers/101
Now container with CTID=101 is ready for use and can be started on '''any''' Pstorage client node (note, however, that you need to register container first if want to run on node different from creator one):
vzctl start 101
In order to quickly relocate the container to another node (w/o data migration), just stop and unregister it on source node, then register and start on destination.
==Upgrading to Parallels Cloud Server==What is '''[http://www.parallels.com/products/pcs/ Parallels Cloud Server]? Parallels Cloud Server ''' is a unique virtualization server platform combining both hypervisor & containers and container-based virtualization together with innovative storage virtualization [http://www.parallels.com/fileadmin/parallels/documents/hosting-cloud-enablement/pcs/Production_Datasheets/ParCloudServer6_DataSheet_EN_Ltr_111312.pdf]. Please request more information on upgrading to Parallels Cloud Server at the [http://www.parallels.com/products/pcs/ product page] (look for '''Request Information''' button).
* Parallels Cloud Server [http://www.parallels.com/fileadmin/parallels/documents/hosting-cloud-enablement/pcs/Production_Datasheets/ParCloudServer6_DataSheet_EN_Ltr_111312.pdf product datasheet].
* Parallels Cloud Storage [http://www.parallels.com/fileadmin/parallels/documents/hosting-cloud-enablement/pcs/Production_Datasheets/ParCloudStorage_DataSheet_EN_Ltr_02262013.pdf product datascheet].
