[Planetlab-users] deletion of slice content

[Micah Beck]

Just a quick note to mention that PlanetLab is home to (at least) two
project that provide distributed file storage service that is robust to
failure of individual nodes: UC Berkeley's OceanStore and the University of
Tennessee's Logistical Networking projects (the L-Bone).  While niether of
them is currently set up to be usable through the standard file system
interface on PlanetLab nodes, there is middleware available that makes it
possible to use the L-Bone in this way.  As the note cross-posted from the
Planetlab-arch mailing list discusses, there would be some work to do to
make this approach general, but it should be feasible.

/micah

----- Original Message ----- 
From: "Micah Beck" <mbeck at cs.utk.edu>
To: <arch at lists.planet-lab.org>
Sent: Wednesday, June 09, 2004 8:10 PM
Subject: Re: [Planetlab-arch] more on sharing files between slices


> Depending on the application requirements, one way for slices to share
> information without sharing files is for them to use a primitive storage
> service that is external to the kernel.  The Internet Backplane Protocol,
a
> service that is running on most PlanetLab nodes, makes such a network
> storage service available through port 6714.  IBP is a public service,
which
> requires no user account or password; privacy is maintained between users
by
> the use of long, randomly generated capabilities as filenames.  IBP and
> tools based on it discussed in this note are research products of the
> Logistical Computing and Internetworking Laboratory (LoCI Lab) within the
> University of Tennessee's Computer Science Department.
>
> Given that IBP can be used to store data, the problem becomes how to share
> the capabilities, and how to synchronize operations between multiple
users.
> The design of IBP supports some synchronization primitives, but not
general
> locking, although that may be added later.  Thus, IBP currently supports
> limited modes of communication and collaboration.
>
> The key data structure used to organize the IBP allocations is called an
> exNode, which is intended to be an exposed network analogy to the file
> system inode.  The exNode stores multiple IBP capabilities and attendant
> file metadata, and expresses a mapping from the virtual linear data extent
> of a network file to multiple IBP allocations, which can store fragmented,
> replicated or erasure encoded, compressed, or encrypted data segments.  A
> set of tools called the Logistical Runtime System or LoRS exists for
> creating and managing exNodes, and there have been various projects that
> implement POSIX file operations using exNodes as file descriptors.
However,
> collaborative use of the files represented by exNodes requires a protocol
> for sharing them.
>
> Early protocols for managing exNodes were manual, such as a single writer
> creating an exNode and then e-mailing it to multiple readers (different
> capabilities for reading and writing are used to protect the data from the
> readers).  More recently, a Web-based directory service called the
> Logistical Distribution Network (LoDN, pronounced "lowdown") has been
> unveiled by LoCI Lab for managing exNodes and providing download via HTTP.
> LoDN also includes Java-based facilities for uploading local file to
exNodes
> and downloading the contents of exNodes to local files.  However, this is
> still a publication interface rather than a true file sharing mechanism
(it
> has no syncrhonization between fine-grained read/write operations).
>
> IBP and the exNode present a highly flexible platform on which a
distributed
> shared file system could be built at user level, allowing sharing of files
> without any kernel support at all.  The addition of syncrhonization
> primitives to IBP would allow IBP capabilities (perhaps exNodes) to be
> stored in IBP allocations and fine-grained operaitons to be managed
> cooperatively.  The great benefit would be the flexibility of having the
> entire implementation of the file system at user level, except for the
most
> primitive operations (storage, data movement, synchronization, perhaps
some
> updating of exNodes in place).  The use of capabilities would provide a
> means to limit the exposure to damage due to the intimate sharing of file
> descriptors (no equivalent of root access to an entire volume).
>
> The creation of a shared file system based on IBP and exNodes is of great
> interest to myself and my colleagues at the Logistical Computing and
> Internetworking Laboratory at the University of Tennessee.  If there were
a
> community of interest in such a project within PlanetLab, we would
certainly
> be interested in collaborating with others on such an ambitious project.
>
> Information about IBP, the exNode, LoRS and LoDN can be found at the LoCI
> lab Web site:
>
> http://loci.cs.utk.edu
>
> Micah Beck
> Director, LoCI Lab
> Associate Professor, Computer Science
> University of Tennessee
>
> ----- Original Message ----- 
> From: "Steve Muir" <smuir at cs.princeton.edu>
> To: <arch at lists.planet-lab.org>
> Sent: Wednesday, June 09, 2004 7:05 PM
> Subject: [Planetlab-arch] more on sharing files between slices
>
>
> > and the general subject of inter-VM communication: i posted a paper we
> > recently wrote on this subject to the AnnotatedBibliography Wiki topic.
> >
> > cheers,
> >
> > steve
> >
> > _______________________________________________
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> > http://lists.planet-lab.org/mailman/listinfo/arch
> >
>