Cloud Storage Models

● Instance storage: Virtual disks in the cloud

● Volume storage: SAN

● Object storage: Web-scale NAS

 Instance storage
● An instance store provides temporary block-level storage for your instance.

This storage is located on disks that are physically attached to the host

computer.

● Instance store is ideal for temporary storage of information that changes

frequently, such as buffers, caches, scratch data, and other temporary

content.

● It can also be used to store temporary data that you replicate across a fleet

of instances, such as a load-balanced pool of web servers.

Instance storage
 Volume storage: SAN

● SAN technology addresses advanced enterprise storage demands

by providing a separate, dedicated, highly scalable
high-performance network designed to interconnect a multitude
of servers to an array of storage devices.
● The storage can then be organized and managed as cohesive pools
or tiers.
● A SAN enables an organization to treat storage as a single
collective resource that can also be centrally replicated and
protected, while additional technologies, such as data
deduplication and RAID, can optimize storage capacity and vastly
improve storage
 NAS (Network Attached Storage)
● An NAS device is a storage device connected to a network that allows
storage and retrieval of data from a central location for authorised network
users and varied clients.

● NAS devices are flexible and scale out, meaning that as you need additional
storage, you can add to what you have.

● NAS is like having a private cloud in the office.

● It’s faster, less expensive and provides all the benefits of a public cloud on
site, giving you complete control.
 Filesystem
● Filesystem is the way in which files are named and where
they are placed logically for storage and retrieval. Without a
file system, stored information wouldn't be isolated into
individual files and would be difficult to identify and
retrieve.
● As data capacities increase, the organization and
accessibility of individual files are becoming even more
important in data storage.
● File systems can differ between operating systems (OS), such
as Microsoft Windows, macOS and Linux-based systems
 How file systems work

● A file system stores and organizes data and can be thought of as a type of index
for all the data contained in a storage device. These devices can include hard
drives, optical drives and flash drives.

● File systems specify conventions for naming files, including the maximum
number of characters in a name, which characters can be used and, in some
systems, how long the file name suffix can be. In many file systems, file names
are not case sensitive.
 Filesystem
● A file system also includes a format to specify the path to a file through the structure of

directories.

● A file is placed in a directory -- or a folder in Windows OS -- or subdirectory at the desired place

in the tree structure. PC and mobile OSes have file systems in which files are placed somewhere

in a hierarchical tree structure.

● Before files and directories are created on the storage medium, partitions should be put into

place.

● A partition is a region of the hard disk or other storage that the OS manages separately. One file

system is contained in the primary partition, and some OSes allow for multiple partitions on one

disk. In this situation, if one file system gets corrupted, the data in a different partition will be

safe.
 Types of Filesystem
● File allocation table (FAT) is supported by the Microsoft Windows OS. FAT is
considered simple and reliable, and it is modeled after legacy file systems. FAT
was designed in 1977 for floppy disks, but was later adapted for hard disks.
While efficient and compatible with most current OSes, FAT cannot match the
performance and scalability of more modern file systems.
● Global file system (GFS) is a file system for the Linux OS, and it is a shared disk
file system. GFS offers direct access to shared block storage and can be used as a
local file system.
● GFS2 is an updated version with features not included in the original GFS, such
as an updated metadata system. Under the terms of the GNU General Public
License, both the GFS and GFS2 file systems are available as free software.
 Types of Filesystem
● Hierarchical file system (HFS) was developed for use with Mac operating systems. HFS can
also be referred to as Mac OS Standard, and it was succeeded by Mac OS Extended.
Originally introduced in 1985 for floppy and hard disks, HFS replaced the original
Macintosh file system. It can also be used on CD-ROMs.

● The NT file system -- also known as the New Technology File System (NTFS) -- is the
default file system for Windows products from Windows NT 3.1 OS onward.
Improvements from the previous FAT file system include better metadata support,
performance and use of disk space. NTFS is also supported in the Linux OS through a free,
open-source NTFS driver. Mac OSes have read-only support for NTFS.
RAID Redundant Array of Independent (or Inexpensive) Disks.

● Combines multiple physical disk drive components into one or

more logical units for data redundancy, performance
improvement, or both.
● RAID combines several independent and relatively small disks
into single storage of a large size.
● The disks included in the array are called array members.
● The disks can combine into the array in different ways, which
are known as RAID levels.
 Characteristics:
● Fault-tolerance is the ability to survive one or several disk failures.
● Performance shows the change in the read and writes speed of the
entire array compared to a single disk.
● The array's capacity is determined by the amount of user data
written to the array.
● The array capacity depends on the RAID level and does not always
match the sum of the RAID member disks' sizes. To calculate the
particular RAID type capacity and a set of member disks, you can
use a free online RAID calculator.
 Three key concepts in RAID

● Mirroring: copying data to more than one disk

● Striping: splitting data across more than one disk
● Error correction (fault tolerance): redundant data is stored
to allow problems to be detected and possibly fixed.
● (Striped set without parity / Non-Redundant
Array) Implements data striping, where file
blocks are written across multiple disks in
fragments that require a minimum of two
disks.
● The advantage of a RAID 0 is that the
read/write speed is dramatically increased.
The more disks that are in the array, the
greater the bandwidth.
● The disadvantage to a RAID 0 is that it has
no fault tolerance. If a single drive fails, the
array is broken. Also, RAID 0 does not
implement error checking. So, any error is
also unrecoverable.
● A common solution for fault tolerance is to
have a drive outside of the array that is used
as backup storage in a hardware failure.
● Mirrored set without parity)
Implements data mirroring. Data is
duplicated on 2 or 4 disks through a
hardware raid controller and provides
some fault tolerance.
● The array is recoverable if at least one
drive does not fail.
● It provides faster read performance
than a single drive and provides drive
redundancy if a drive failure occurs.
Write speed is slightly reduced.
● Creates multiple mirrors,
where data is organized as
stripes across multiple disks
and then the striped disk
sets are mirrored.
● RAID 10 offers the same
fault tolerance as RAID 1
with increased read/write
speeds over a single Raid 1
volume or single drive.
● RAID Level 10 requires four
disks to implement.
● RAID 3 combines parity and
striping with stored parity bits
on a dedicated disk, this
configuration requires at least
three separate hard disks – two
for striping data and one for
storing parity bits

RAID 3 advantages include:

● High throughput for
transferring large amounts of
data
 Assignment
RAID 4, RAID 5, RAID 6