February 12, 2009"> 7"> ganeti"> Debian"> GNU"> GPL"> ]> 2006 2007 2008 2009 Google Inc. &dhdate; &dhucpackage; &dhsection; ganeti 2.0 &dhpackage; cluster-based virtualization management # gnt-cluster init cluster1.example.com # gnt-node add node2.example.com # gnt-instance add -n node2.example.com \ > -o debootstrap --disk 0:size=30g \ > -t plain instance1.example.com The ganeti software manages physical nodes and virtual instances of a cluster based on a virtualization software. The current version (2.0) supports Xen 3.0 (also tested with 3.1) and KVM hypervisors. First you must install the software on all the cluster nodes, either from sources or (if available) from a package. The next step is to create the initial cluster configuration, using gnt-cluster init. Then you can add other nodes, or start creating instances. In Ganeti 2.0, the architecture of the cluster is a little more complicated than in 1.2. The cluster is coordinated by a master daemon ( ganeti-masterd 8 ), running on the master node. Each node runs (as before) a node daemon, and the master has the RAPI daemon running too. Each node can be in one of the following states: master Only one node per cluster can be in this role, and this node is the one holding the authoritative copy of the cluster configuration and the one that can actually execute commands on the cluster and modify the cluster state. See more details under Cluster configuration. master_candidate The node receives the full cluster configuration (configuration file and jobs) and can become a master via the gnt-cluster masterfailover command. Nodes that are not in this state cannot transition into the master role due to missing state. regular This the normal state of a node. drained Nodes in this state are functioning normally but cannot receive new instance, because the intention is to set them to offline or remove them from the cluster. offline These nodes are still recorder in the ganeti configuration, but except for the master daemon startup voting procedure, they are not actually contacted by the master. This state was added in order to allow broken machines (that are being repaired) to remain in the cluster but without creating problems. The master node keeps and is responsible for the cluster configuration. On the filesystem, this is stored under the @LOCALSTATEDIR@/ganeti/lib directory, and if the master daemon is stopped it can be backed up normally. The master daemon will replicate the configuration database called config.data and the job files to all the nodes in the master candidate role. It will also distribute a copy of some configuration values via the ssconf files, which are stored in the same directory and start with ssconf_ prefix, to all nodes. All cluster modification are done via jobs. A job consists of one or more opcodes, and the list of opcodes is processed serially. If an opcode fails, the entire job is failed and later opcodes are no longer processed. A job can be in one of the following states: queued The job has been submitted but not yet processed by the master daemon. waiting The job is waiting for for locks before the first of its opcodes. canceling The jos is waiting for locks, but is has been marked for cancelation. It will not transition to running, but to canceled. running The job is currently being executed. canceled The job has been canceled before starting execution. success The job has finished successfully. error The job has failed during runtime, or the master daemon has been stopped during the job execution. &footer;