CIT 1100

Advanced Storage Topics

In this chapter you will learn how to: Explain how hard drives store data Describe the differences between traditional hard drives and flash-based storage

Explain how SCSI technology works

Advanced Storage Topics

There are 2 steps required to prepare any hard drive to store data: Partitioning and Formatting

Partitioning creates distinct sections on a hard drive. Hard drives can have a single partition or multiple partitions each partition appears as a separate drive

Using Hard Drives

Partitioning can make a single drive appear to the Operating system as separate devices

There are 2 steps required to prepare any hard drive to store data: Partitioning and Formatting

For matting creates a file system for the drive essentially a large database that tracks what piece of data is stored in which location

Without a file system the O/S couldn’t locate anything

Windows supports three different file systems: FAT, FAT32, and NTFS

Using Hard Drives

All OSes support the File Allocation Table (FAT) format, the oldest format of the three FAT will not support partitions larger than

2.1 GB and includes no security, it's become obsolete

FAT32 is the 32-bit version of FAT and can handle partitions as large as 2 TB, with no provision for security

FAT and FAT32 used in flash media storage but usually not on larger hard drives

Filesystems

NTFS is the preferred formatting solution for newer hard drives, handling partitions up to 16 TB and includes built-in compression and encryption capabilities

Filesystems

Typical hard drives used today have platters that spin at high speed under a small read/write head The platters are coated with special materials

that can assume magnetic properties used to store the binary information

This method has been used for years as an inexpensive way to store large amounts of data

Hard drives by design have many high speed moving parts that can wear out and cause problems in time

All Hard Drives will eventually fail

Hard Drive Storage

Unlike hard drives, flash-based storage has no moving parts, making it faster and more reliable Flash-based storage uses small memory chips instead

of platters to store data, similar to how RAM works, but it’s non-volatile

You can write to them, read from them, and delete data just as you would on an HDD

Flash-based storage can be found in many portable devices, including phones, MP3 players, GPS navigation systems, e-book readers, and more

Over time the cost has dropped to the point where it can be considered as a replacement for HDD

Flash-Based Storage

Popular memory card formats include:◦ CompactFlash◦ SDHC 32 G, SDXC 2TB, miniSD, and microSD◦ xD-Picture Card◦ Memory Stick 

Flash-Based Storage

When you finish using the memory card and want to download the data back to your computer, you have two options: plug in the device directly using a USB cable or use a memory card reader and writer.

A comparison of an SSD to an Hard drive shows that both have strengths and weaknesses SSDs have four advantages over HDDs:

1. Speed 2. Physical durability 3. Energy use 4. Storage efficiency

Traditional Storage vs. Flash-Based Storage

A comparison of an SSD to an Hard drive shows that both have strengths and weaknesses Hard Drives have three advantages over

SDD:

1. Price 2. Capacity 3. Electronic longevity

Traditional Storage vs. Flash-Based Storage

Most of the advantages to using flash-based storage over traditional hard drives is due to the fact that traditional hard drives contain several moving pieces The fact that there needs to be movement at

all makes traditional hard drives very slow devices, compared to the rest of a computer.

Traditional hard drives also use more energy to drive all the moving parts

Traditional Storage vs. Flash-Based Storage

It takes ~ 5 ms to move the r/w head to the correct track seek time

With no moving parts to break or power flash-based devices are tougher and use less energy

SSDs retrieve data more efficiently than HDDs enabling them to ignore one of the primary causes for slowness with HDDs - fragmentation A utility in Windows (and other OSes) called

Disk Defragmenter can fix fragmentation Windows 7 runs it automatically, Windows XP,

you need to run the utility manually Because SSDs don't have a read/write arm to

move to retrieve data, fragmentation doesn't matter. Data is just retrieved.

Never defragment SDD devices

Traditional Storage vs. Flash-Based Storage

HDDs offer the best capacity at the lowest price of any fast storage device. You can buy a two-terabyte (TB) drive for under $200 One issue with SSDs is that repeatedly

deleting and rewriting of data will, over time, make the drives slower in writing data. Newer ones aren't so bad and will undoubtedly improve.

The cost of SDD is still considerably higher than standard HDD 120GB ~ $120.00

Traditional Storage vs. Flash-Based Storage

The Small Computer System Interface (SCSI) is an old technology dating from the late1970s peripherals, including scanners and printers, used SCSI At the time it was faster than the other buses

available at that time With the new USB3, FireWire, and eSATA

connectors, SCSI ports have all but disappeared from most computers

SCSI

A key feature of SCSI is the SCSI chain. Most interfaces work on the principle of 1connector 1device SATA for example, enables a single hard drive to

connect to the motherboard. Some like PATA string together two hard drives on a single ribbon cable. SCSI takes this concept one step further with the idea of a SCSI chain

The chain begins inside the computer. Some systems include a built-in SCSI connectors,

others used a separate device known as a SCSI host adapter that can add 2 connectors on for internal one for external

SCSI Chains

SCSI could connect up to 14 devices on a single channel

Connected drives are part of a SCSI chain (Bus), either internal, external, or both Internal chains are made using cables with multiple connectors, external chains are created connecting one device to another known as a daisy chain

SCSI Chains

When connecting more than one device you need to provide a way for the host adapter to differentiate them. SCSI ID is a number ranging from 0 to 15 that is assigned to each device on the SCSI chain

Jumpers could be used to designate SCSI ID numbers similar to Master/Slave settings on Drives