CIT 1100
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
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 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 Formatting 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
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
NTFS is the preferred formatting solution for newer hard drives, handling partitions up to 16 TB and includes built-in compression and encryption capabilities
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
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
Popular memory card formats include: ◦ CompactFlash ◦ SDHC 32 G, SDXC 2TB, miniSD, and microSD ◦ xD-Picture Card ◦ Memory Stick ◦ Memory Stick 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
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
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 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
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 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
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
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 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 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