[Planetlab-users] 5GB disk space limits on PlanetLab nodes

[Micah Beck]

PlanetLab users who have large storage needs are invited to make use of the
Logistical Backbone (L-Bone), a shared, public storage infrastructure.   The
resources available in the L-Bone are there to be taken advantage of by
projects and users such as those that make up the PlanetLab community.  You
can see a summary of L-Bone resources here:

http://loci.cs.utk.edu/lbone/cgi-bin/lbone_view.cgi?location=all&op=list&sortBy=depot

The core mechanism of Logistical Networking is the Internet Backplane
Protocol (IBP), a data management protocol that was devised to allow the
scalable sharing of storage resources.  The keys to its scalability are its
best effort nature and time limited, weak semantics, which you can read
about in this paper from SIGCOMM 2002:

http://loci.cs.utk.edu/modules.php?name=Publications&d_op=ViewPublication&lid=133

A suite of tools called the Logstical Runtime System (LoRS) has been
developed to implement stronger services on top of IBP, recovering the
properties such as reliability, security, and performance through the use of
end-to-end protocols that implement fragmentation, replication/erasure
coding, checksums, encryption, etc.  A manual on the use end-user tools in
the LoRS suite can be found here:

http://loci.cs.utk.edu/modules.php?name=Publications&d_op=ViewPublication&lid=226

The easiest way to start using the L-Bone is through the Web interface of
the Logistical Distribution Network, which you can reach about here:

http://promise.sinrg.cs.utk.edu/lodn/doc/Intro.htm

IBP has two modes of allocation for storage resources: hard and soft.  Hard
allocations are best effort, meaning that the IBP depot (our name for the
IBP server) will make do its best to preserve and provide access to the data
stored there.  Soft allocations can be revoked by the depot according at its
own discretion, even before the duration of allocation has expired.  The
policy we have implemented makes soft allocations from the free space in the
depot's file system, and deletes them when the file system reaches some
threshold of fullness.  There is no warning or notification to the user
until they try to access their data.  Our current deletion policy is based
on the age of the allocation.

The L-Bone is currently implemented using the storage resources of PlanetLab
nodes, and so on August 24 the storage available to it will be reduced  from
its current maximum of 40 TB.  However, there are also non-PL servers in the
L-Bone (some major nodes are part of an NSF Project called the National
Logistical Networking Testbed, others are contributed by collaborating
institutions).

All PlanetLab nodes are welcome to use the resources of the L-Bone for their
own purposes, in hard or soft allocation mode (there is currently 10TB
available for hard allocation on the L-Bone).  We ask you to be considerate
in your use of the L-Bone in the same way that you are considerate in your
use of the Internet, by backing off when storage resources seem to be
getting full on any particular node.  With the L-Bone, there may be other
nodes you can find to store data on, perhaps not exactly where you prefer to
store your data, but still adequately accessible.  Part of the Logistical
Networking research program (which we invite members of the PlanetLab
community to join us in) is to devise TCP-like algorithms to ensure such
neighborly sharing of resources and incorporate them into the LoRS
middleware stack.

We would like to see the L-Bone used to help alleviate the PL storage
crunch.  It is also possible that IBP soft allocation could be used as a
local service to allow users on a single PL node to share the free space in
the node's file system while still enforcing per-slice quotas on file space.
The Logistical Networking model can have a number of benefits in an
community that relies so heavily on resource sharing and network
communication to build distributed systems.

Micah Beck
Director, Logistical Computing and Internetworking Lab
Associate Professor, Computer Science
University of Tennessee
http://loci.cs.utk.edu

----- Original Message ----- 
From: "Marc E. Fiuczynski" <mef at cs.princeton.edu>
To: <users at planet-lab.org>
Sent: Wednesday, August 18, 2004 7:38 AM
Subject: [Planetlab-users] 5GB disk space limits on PlanetLab nodes


> When is this happening:
>
> Starting August 24th 2004, production systems will start to enforce a per
> slice 5GB disk space limit.
>
> Who is affected:
>
> Most users will be unaffected by this.  Users needing to create large log
> files should prepare for this limit.  Users operating long-running
services
> with large disk space requirements (e.g., CDNs) are the most likely to be
> affected by this change.
>
> What if you are using >5GB of disk space on a node:
>
> You will be contacted via your slice email alias and asked to reduce your
> disk space usage on that node.
>
>   -- PlanetLab Operations
>
> _______________________________________________
> Users mailing list: Users at lists.planet-lab.org
> http://lists.planet-lab.org/mailman/listinfo/users
>