Data Storage Solutions Data Storage Solutions

Module 1.2

Data Storage Solutions

Upon completion of this module, you will be able to:

List the common storage media and solutions.

Describe the three common storage environments.

Lesson: Storage Solution Alternatives

Upon completion of this lesson, you will be able to:

Describe the different media and solutions available to address data storage needs of a business.

Describe the role of each solution in the overall data storage needs.

Describe the advantages of disk arrays.

Common Data Storage Media

As the need for storing large amount of data grows, each of these can be combined and housed in central units.– A collection of tape drives and tapes – Tape library

– A collection of optical disks and drives – Jukeboxes

– A collection hard disks – Disk Arrays

Each solution addresses specific needs for data storage and management.– Tape Library – Backup/Restore; Archival of data

– Jukeboxes – Typically to store non-changing content over long periods of time

– Disk Arrays – To store data that has to be immediately accessible and on-line

Tape Storage Systems

• Tape based storage is relatively inexpensive, compared to disk arrays.

• They served as primary storage solutions in the early days.

• Tape drives use Read/Write heads to record bits of data onto magnetic material on the tape surface.

• Far from being abandoned, this technology continues to evolve, providing higher storage capacity, greater reliability, and improved performance.

Storing Data on Tape

Data is recorded sequentially from the beginning to end, one byte after another.

Because data is stored linearly along the length of the tape, random access to specific bits of data is slow and time consuming. This severely limits tape as a medium for real-time, rapid access to data.

Tapes cannot be shared among multiple users or applications.

Optical Data Storage

• Popular in small, single-user computing environments.

• Frequently used by individuals to store and share data, or as backup solution.

• Also used as distribution medium for applications, or as a means of transferring small amounts of data from one self-contained system to another.

Disk Based Storage

From a historical perspective, we will explore the following disk based storage solutions:

• DASD: Direct Access Storage Device

• JBOD: Just a Bunch Of Disks

• Disk Arrays

• “Intelligent” Disk Arrays

Types of Disk Systems: DASD

Mainframe

Disk

• Introduced by IBM in 1956.

• The ‘oldest’ of the techniques for accessing disks from a host computer.

• Disks are accessed directly by a single host, historically a mainframe system.

Types of Disk Systems: JBOD

Host

Disk Disk Disk Disk Disk

• Multiple physical disks in an external cabinet.

• Array connects to a single server only.

• Provides higher storage capacity with increased number of drives.

• Data not protected.

Array

Types of Disk Systems: Disk Arrays

Host B

Disk 1 Disk 2 Disk 3 Disk 4 Disk 5

Disk ArrayController

Array controllers for optimized I/O operations and RAID calculations.

Higher speed interconnects between drives, than JBODs.

Multiple host I/O channels.

Can be partitioned to allow each host to access its own set of drives.

Host A Host C

Host A Host B Host C

Types of Disk Systems: “Intelligent” Disk Arrays

Host

Disk 1 Disk 2 Disk 3 Disk 4 Disk 5

Disk ArrayController

Highly optimized for I/O processing.

Cache for improving I/O performance.

Operating environments provide: Intelligence for managing Cache,

Array resource allocation,

Host access to Array resources,

Connectivity for heterogeneous Hosts

Lesson: Summary

Topics covered in this lesson included:

Tape

Optical

Disks – DASD

– JBOD

– Disk Arrays

– Intelligent Disk Arrays

Lesson: Storage Environment

Upon completion of this lesson, you will be able to:

Describe Direct Attached Storage (DAS) features.

Describe Storage Area Network (SAN) features.

Describe Network Attached Storage (NAS) features.

DAS

Client 2

Server AApplication A

Server BApplication B

Server CApplication C

Disks for Server A

Disks for Server B

Disks for Server C

Client 3

Client 1

Network

NAS

Disks for File System A

Disks for File System B

NAS Device AFile System A

NAS Device BFile System B

Internal/External connectivityto disks or arrays

SAN

Client 2

Client 3

Client 1 Server AApplication A

Server BApplication B

Server CApplication C

Disks for Server A

Disks for Server B

Disks for Server C

SAN

Direct Attached Storage (DAS)

Characteristics:-Storage devices attached directly to servers (only point of access)

DAS, cont.

Components-Most use SCSI-Most use a redundant array of independent disks (RAID) to protect data against single-disk failure-Server is the performance bottleneck

DAS, cont.

Strengths & Limitations:-They are relatively inexpensive, familiar to most IT departments, and are widely usable.-However, single-server access is limiting, and DAS networks have distance limitations

Network Attached Storage (NAS)

Characteristics:-Essentially specialized servers dedicated to storage provision-Unlike DAS, NAS allows any user to directly access resources-Typically use platform-independent file systems

NAS, cont.

Components:-Storage appliance contains a “thin” server-Server uses its own host-independent filesystem-Connects directly to the LAN

NAS, cont.

Strengths & Limitations:-NAS enables faster access to applications, multiple servers can access the same device, and a NAS is more reliable than a DAS-A NAS environment is limited by LAN bandwidth, and can still bottleneck at the NAS server itself

Storage Area Networks (SANs)

SANs, cont.

Components:-Fibre Channel is the most common interconnect technology.-Can use a variety of media, including fiber optic cables, coaxial cables, or twisted pair wiring.-Other components include HBAs, transceivers, hubs, and switches.

SANs, cont.

Strengths & Limitations:-Provide highly scalable performance, allow hosts to implement storage file systems (allowing them to use file systems best suiting their applications).-SANs are also much more expensive than other storage networking solutions, and do not allow heterogenous operating systems to access the same storage resources.

Organizations & Standards

Storage Networking Industry Association (SNIA)

Fibre Channel Industry Association (FCIA)

International Committee for Information Technology Standards (iNCITS)

Supported Solutions Forum (SSF)

SANmark Qualified Program

Open Standards Fabric Initiative (OSFI)

Shared Storage Model

Lesson: Summary

Topics covered in this lesson included:

Direct Attached Storage (DAS) features.

Network Attached Storage (NAS) features.

Storage Area Network (SAN) features.

Module Summary

Key points covered in this module:

The three types of data storage media.

The three storage interconnect models.

Check Your Knowledge

What are the three most common storage media?

What are the three types of disk-based solutions?

What are the advantages of a disk-based storage solution?

What are the three storage interconnect models?

Why is a SAN solution the best alternative for large storage environments?