Snowflock
Материал из Xgu.ru
Hi everyone,
we're releasing Snowflock to the general public. We're making a binary and
source relase, under the GNU General Public License (GPL). The release is
available at http://compbio.cs.toronto.edu/snowflock.
Briefly, Snowflock lets you clone Xen VMs into dozens of identical
replicas running in different hosts. Snowflock can do this in less than a
second and with very low runtime overhead. With Snowflock you can, for
example, perform parallel computations on the fly by scaling
"instantaneously" your computing footprint in a shared cluster. Snowflock
is a research prototype, hence the 0.1 major-minor. A minimum degree of
experience with Xen and Linux is necessary to use the system. The contact
address for snowflock is snowflock-users@cs.toronto.edu
More technically:
Snowflock is our prototype implementation of the / Impromptu Cluster (IC)/
abstraction. In an IC, an application encapsulated inside a virtual machine
(VM) is swiftly forked into multiple copies that execute on different
physical hosts, and then disappear when the computation ends. ICs simplify
the development of parallel applications and reduces management burden by
enabling the instantiation of new stateful computing elements: workers that
need no setup time because they have a memory of the application state
achieved up to the point of forking. This approach combines the benefits of
cluster-based parallelism with those of running inside a VM.
Snowflock provides swift parallel VM cloning that makes it possible for
Internet applications to deliver near-interactive performance for
resource-intensive highly-parallelizable tasks. Snowflock makes use of
four key techniques: /VM descriptors/ (condensed VM images that allow for
sub-second suspension of a running VM and resumption of a of replicas); a
/memory-on-demand/ subsystem that lazily populates the VM's memory image
during runtime; a set of / avoidance heuristics/ that minimize the amount
of VM memory state to be fetched on demand; and a /multicast distribution/
system for commodity Ethernet networking hardware that makes the overhead
of instantiating multiple VMs similar to that of instantiating a single
one.
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