Learning objectives • Understand how to handle massive amount of data using data grid. • Explains data replication and namespaces • Identify the various data access model.

1. CS6703- GRID AND CLOUD
COMPUTING
2.6. Data Intensive Grid Service Models
By
M.Gomathy Nayagam, AP(SG)/CSE
Ramco Institute of Techonolgy, Rajapalayam

2. DATA INTENSIVE GRID SERVICE MODEL
 Grid applications are grouped together as:
 Computation intensive
 Data intensive.
 Data intensive- application have to deal with
massive amount of data.
 Example: Large Hadron Collider data set exceeds
several peta bytes by every year.
 Data intensive grid system designed to discover,
transfer, and manipulate these massive data sets.
 Transferring massive data is time consuming one
 Let us discuss some mechanism for solving data
movement problems.

3. DATA REPLICATION AND UNIFIED NAMESPACE.
 Data access method is known as caching.
 Caching –enhance the data efficiency.
 Replication – stores the same data block and scatter
them in multiple regions of grid.
 Hence user can access the same data with locality of
reference.
 Key data will not lose incase of failure.
 But, it increases storage requirements and network
bandwidth.
 Replication strategies determine when and where to
create a replica of the data.
 The factors to consider include data demand, network
conditions, and transfer cost.

4. DATA REPLICATION AND UNIFIED NAMESPACE.
 Two types of replication strategies are:
 Static replication
 The locations and number of replicas are determined in
advance and will not be modified.
 It cannot be suitable to adapt for changes in demand,
bandwidth, and storage availability
 Dynamic replication - adjust locations and number of
data replicas according to changes in conditions
 Frequent data-moving operations can result in
much more overhead than in static strategies.
 The replication strategy must be optimized with
respect to the status of data replicas.

5. GRID DATA ACCESS MODEL
 Multiple participants may want to share the same data
collection.
 To retrieve any piece of data, a grid with a unique global
namespace is needed.
 Similarly, need to have unique file names.
 So, we need to resolve inconsistencies among multiple data
objects bearing the same name.
 Data needs to be protected to avoid leakage and damage.
 Users who want to access data have to be authenticated first
and then authorized for access.
 There are 4 data access models:
 Monadic Model
 Hierarchical Model
 Federation Model
 Hybrid Model

6. GRID DATA ACCESS MODEL
Monadic model:
 Centralized data repository
model
 data is saved in a central data
repository
 Users have to submit requests
directly to the central
repository for accessing data.
 No data is replicated for
preserving data locality.
 It is a simple model.
 Data replication is permitted in
this model only when fault
tolerance is demanded.

7. GRID DATA ACCESS MODEL
Hierarchical model:
 It is suitable for building a large
data grid
 The data may be transferred
from the source to a second-
level center.
 Then some data in the regional
center is transferred to the
third-level center.
 After being forwarded several
times, specific data objects are
accessed directly by users.

8. GRID DATA ACCESS MODEL
Federation Model:
 It is suited for designing a data
grid with multiple sources of data
supplies.
 This model is also known as a
mesh model.
 The data sources are distributed
to many different locations.
 Although the data is shared, the
data items are still owned and
controlled by their original owners.
 According to predefined access
policies, only authenticated users
are authorized to request data
from any data source.

9. GRID DATA ACCESS MODEL
Hybrid Model
 The model combines the best
features of the hierarchical
and mesh models.
 Traditional data transfer
technology, such as FTP,
applies for networks with
lower bandwidth.

10. PARALLEL VERSUS STRIPED DATA
TRANSFERS
 Parallel data transfer opens multiple data streams
for passing subdivided segments of a file
simultaneously.
 Although the speed of each stream is the same as
in sequential streaming, the total time to move data
in all streams can be significantly reduced
compared to FTP transfer.
 In striped data transfer, a data object is partitioned
into a number of sections, and each section is
placed in an individual site in a data grid.