UbiStore: Ubiquitous and
Opportunistic Backup Architecture.
Feiselia Tan, Sebastien Ardon, Max Ott
Presented by: Zainab Aljazzaf
Table of contents:
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Introduction.
Goals and constrains.
UbiStore overviews.
- Assumptions.
- Evaluation criteria.
- Model.
Node Architecture.
Evaluation.
- Simulation mobility models.
- Simulation result.
Related Work.
Conclusion.
Table of contents:
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Introduction.
Goals and constrains.
UbiStore overviews.
- Assumptions.
- Evaluation criteria.
- Model.
Node Architecture.
Evaluation.
- Simulation mobility models.
- Simulation result.
Related Work.
Conclusion.
Introduction ..
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To prevent data loss in case of malfunctioning or
lost devices.
Backup!
Backup has to be done periodically and often
manually  up to date?
Portable backup system
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Many of these devices have, or soon, will
have wireless connectivity.
Mobile Computing Environments
Introduction
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Mobile devices (mobile telephones, personal
audio players, PDA, laptop computers .. etc)
are used in many locations and environments
than desktop computers.
Those devices continuously record user’s life
artifacts.
Storage is mainly local to the device.
Mobile lost !
BACKUP …
Introduction ..
- Backup cards:
SIM Card information
backup machine
Mobile backup card
USB SIM card reader
- Mobile Backup system: AT&T mobile backup service allow its
subscribers to store, update and access their contact information
from the Web.
Introduction ..
- Mobile backup system:
Introduction ..
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The data volume and associated network cost
makes traditional backup to a backup server cost
prohibitive for most consumers.
What is needed is an automatic and ideally
operating cost free solution for mobile devices.
Use short-range and peer-to-peer communication
capability.
UbiStore: a backup architecture, where mobile
devices backup their data over short-range, adhoc wireless links to other devices encountered as
a result of user mobility.
UbiStore
Mobile to mobile backup
- Main idea: typical user
mobility patterns will incur some
repetitive encounters in the course
of daily life (public transports,
home/office) which can facilitate
the recovery of data in case of a
device failure.
Table of contents:
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Introduction.
Goals and constrains.
UbiStore overviews.
- Assumptions.
- Evaluation criteria.
- Model.
Node Architecture.
Evaluation.
- Simulation mobility models.
- Simulation result.
Related Work.
Conclusion.
Goals and constrains ..
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No need for 100% recovery.
Fully decentralized architecture.
Only short-range, peer-to-peer
communication.
Maintain user’s privacy and data integrity.
Maximize the incentive to participate.
Table of contents:
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Introduction.
Goals and constrains.
UbiStore overviews.
- Assumptions.
- Evaluation criteria.
- Model.
Node Architecture.
Evaluation.
- Simulation mobility models.
- Simulation result.
Related Work.
Conclusion.
UbiStore overviews : Assumptions ..
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The exponential increase of mobile device’s
storage satisfy the user needs.
The existence of free P2P communication
(Blutooth) -> discovery mode.
Encounter of other devices during the day.
Human activity is largely repetitive.
A unique information can survive the loss.
UbiStore overviews : Evaluation criteria ..
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The recovery time: Time necessary to restore lost data.
It is the most important parameter as it deals with direct
user’s perception of the system’s performance.
The space efficiency: Ratio between backup data and
effective data. It is impacting the per-bit cost of the
overall backup system.
The communication efficiency: reflects the communication
overhead of using several peer-to-peer communication
links compared with centralized backup mechanism.
The paper present an initial evaluation of UbiStore using
the recovery time criteria, for two different mobility
models.
UbiStore overviews : Model ..
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A node in UbiStore is a software agent executed on a
user’s device, and assigned a data area to be backed up.
Encounter: the event of two nodes establishing
communication in the view to exchange data.
At any time, each node in UbiStore operates in one of
the following two modes:
- Backup mode: a node keeps sending data blocks to
other nodes while at the same time receiving and storing
data from other nodes.
- Recovery mode: used after a device failure or a lost
device, where a node will seek to recover its data from
any node encountered.
Table of contents:
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Introduction.
Goals and constrains.
UbiStore overviews.
- Assumptions.
- Evaluation criteria.
- Model.
Node Architecture.
Evaluation.
- Simulation mobility models.
- Simulation result.
Related Work.
Conclusion.
Architecture
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Block: the elementary unit of storage in UbiStore.
Blocks are immutable: once generated, they
cannot be modified.
Any block is assigned a globally unique identifier,
associated with an owner.
Blocks are not forwarded from one node to
another node, i.e. a node will only send its own
blocks to another node.
Node Architecture ..
- Block generation process:
Node Architecture ..
- UbiStore node functional overview:
Node Architecture: Data manager
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Choosing which block to send:
Selecting blocks for deletion: blocks to be
deleted are chosen from the tail of the
queue (the blocks we are most likely to
encounter again in the short term are
dropped first).
Node Architecture ..
- Computing storage space offers: several
strategies:
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Fixed size: a constant amount of storage space is
advertised for each encounter.
Adaptive: the offered storage space is biased to
favor frequently encountered nodes, with longer
contact durations -> frequently encountered
nodes are also likely to be frequently encountered
when it is time to recover the data after a failure.
Table of contents:
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Introduction.
Goals and constrains.
UbiStore overviews.
- Assumptions.
- Evaluation criteria.
- Model.
Node Architecture.
Evaluation.
- Simulation mobility models.
- Simulation result.
Related Work.
Conclusion.
Evaluation: simulation mobility models
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The random waypoint model in which nodes evolve in a
two-dimensional square field with their destination and
speed determined randomly.
This model is unrealistic and does not represent any
actual human mobility pattern, we use it to (This will
provide baseline).
Commuters traveling on a train : high level of correlation
between node movements.
Evaluation: Simulation result ..
- Recovery speed vs. time (Random waypoint model):
Evaluation: Simulation result ..
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The variation: recovery ratio vs. time (ratio=5)
Evaluation: Simulation result ..
- Train scenario vs. random waypoint:
This supports the main idea of UbiStore that the repetitiveness of human
mobility over large timescale will increase the speed of date recovery.
Table of contents:
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Introduction.
Goals and constrains.
UbiStore overviews.
- Assumptions.
- Evaluation criteria.
- Model.
Node Architecture.
Evaluation.
- Simulation mobility models.
- Simulation result.
Related Work.
Conclusion.
Related work
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OceanStore and PAST: provide a self-organizing
file system storage infrastructure to applications.
PeerStore: is a backup system. Is not adapted to
disconnected networks and opportunistic
communication.
Pastiche: buddy have similar set of files. Buddies
only exchange data that is not common for both.
Table of contents:
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Introduction.
Goals and constrains.
UbiStore overviews.
- Assumptions.
- Evaluation criteria.
- Model.
Node Architecture.
Evaluation.
- Simulation mobility models.
- Simulation result.
Related Work.
Conclusion.
Conclusion
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The paper has presented the concept and
initial design of UbiStore.
The main idea is to perform backup in other
devices encountered by a mobile device
over time.
The paper presented an early performance
evaluation which shows the benefit of
exploiting repetitive patterns in human
mobility.
Thank you ..