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Ganeti 2.0 design documents
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===========================
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The 2.x versions of Ganeti will constitute a rewrite of the 'core'
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architecture, plus some additional features (however 2.0 is geared
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toward the core changes).
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Core changes
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------------
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The main changes will be switching from a per-process model to a
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daemon based model, where the individual gnt-* commands will be
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clients that talk to this daemon (see the design-2.0-master-daemon
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document). This will allow us to get rid of the global cluster lock
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for most operations, having instead a per-object lock (see
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design-2.0-granular-locking). Also, the daemon will be able to queue
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jobs, and this will allow the invidual clients to submit jobs without
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waiting for them to finish, and also see the result of old requests
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(see design-2.0-job-queue).
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Beside these major changes, another 'core' change but that will not be
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as visible to the users will be changing the model of object attribute
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storage, and separate that into namespaces (such that an Xen PVM
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instance will not have the Xen HVM parameters). This will allow future
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flexibility in defining additional parameters. More details in the
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design-2.0-cluster-parameters document.
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The various changes brought in by the master daemon model and the
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read-write RAPI will require changes to the cluster security; we move
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away from Twisted and use http(s) for intra- and extra-cluster
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communications. For more details, see the security document in the
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doc/ directory.
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Functionality changes
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---------------------
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The disk storage will receive some changes, and will also remove
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support for the drbd7 and md disk types. See the
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design-2.0-disk-changes document.
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The configuration storage will be changed, with the effect that more
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data will be available on the nodes for access from outside ganeti
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(e.g. from shell scripts) and that nodes will get slightly more
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awareness of the cluster configuration.
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The RAPI will enable modify operations (beside the read-only queries
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that are available today), so in effect almost all the operations
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available today via the ``gnt-*`` commands will be available via the
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remote API.
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A change in the hypervisor support area will be that we will support
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multiple hypervisors in parallel in the same cluster, so one could run
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Xen HVM side-by-side with Xen PVM on the same cluster.
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New features
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------------
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There will be a number of minor feature enhancements targeted to
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either 2.0 or subsequent 2.x releases:
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- multiple disks, with custom properties (read-only/read-write, exportable,
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  etc.)
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- multiple NICs
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These changes will require OS API changes, details are in the
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design-2.0-os-interface document. And they will also require many
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command line changes, see the design-2.0-commandline-parameters
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document.