Storage Provisioning and Networking - Deploying and Managing a Cloud Infrastructure - page 247

contains data, corresponding metadata (attributes describing the data), and a globally
unique identifier (called the object ID). This object ID is used to refer and uniquely iden-
tify each object to differentiate it from the others, thus providing a security control mecha-
nism that provides per-object and per-command access control.

FIGURE 9.1 File hierarchy and object store

Documents

Metadata

READ ME
Test.java

Data object (BLOB)
DO5700818

Downloads

Metadata

Resume.pdf
MyVideo.mp4

Data object (BLOB)
DO5700976

File hierarchy Object store

Object-based storage is different than other storage architectures such as file systems and
block storage. A file system manages data in a file hierarchy, whereas block storage treats
data as blocks within disk sectors and tracks. Object storage abstracts lower layers of stor-
age from applications. Low-level storage management functions such as constructing and
managing logical volumes, RAID configuration for disk failure, and disk defragmentation
and compression need not be performed actively.
Object-based storage enables capabilities not offered by other storage architectures. An
object store can be implemented at multiple levels: the device level, the system level, and the
interface level. This enables multiple features:

Namespaces can be declared across multiple machines, thus enabling hardware-level
abstraction.

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Interfaces can be directly programmed by the application to span across multiple disk
drives, thus enabling unified access to data across multiple nodes.

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Data can be distributed and replicated at the granularity level of the object (which can
range from few KBs to GBs).

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Metadata

Metadata, or descriptive metadata to distinguish from structural metadata, refers to data
about data or attributes describing the data . Metadata can also be thought of meta-content
that provides information about one or more aspects of data, such as the following:

Purpose of the data

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Time stamp (time and date) of creation

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