Storing And Retrieving Information Magnetic Interchangeable Disks Can

Storing And Retrieving Information

Magnetic Interchangeable Disks Can be stored offline and loaded to the magnetic disk drives as they are needed -Interchangeable Hard Disks -USB / Micro SD Cards Hard/Fixed Disks Permanently installed and cannot be removed - Data stored on all recording surfaces. - Allows greater density than interchangeable diskettes

Hard Disks �Anatomy: Recording surface Multiple platters Read/write head Access arms Courtesy of Seagate Technology How A Hard Drive Works

Magnetic Disk Organization Tracks & Sectors & Clusters OH MY

Formatting your HARD DRIVE Low-Level Formatting - Creates sectors and tracks on disk into which data are stored. High Level Formatting - Sets up VFAT, Master Boot Record is created, copies hidden operating system files to the volume, and prompts you for a label i. e. MY Computer.

Maintaining your drive � Scan. Disk for lost clusters are the result of an unexpected interruption of file activity, perhaps a system crash or loss of power. The Scan. Disk utility program periodically to “scan” the disk for lost clusters and, if any are found, let you return them to the available pool of usable clusters.

Maintaining your drive � Defragging Reorganizing your files in continuous clusters.

Magnetic Disk Organization Virtual File Allocation Table File Expenses. xls Annual Rep. doc AVAILABLE New. Budget. md b 1 st Cluster 1 2 3 4 Cluster Track 3 1 Sector s 2, 3, 4, 5

VFAT: request for a particular file. 1. 2. 3. 4. 5. The operating system searches the VFAT to find the physical address of the first cluster of the file. The read/write heads are moved over the track/cylinder containing the first cluster. The rapidly rotating disk passes the cluster under/over the read/write head and the information in the first cluster is read and transmitted to RAM for processing. The operating system checks an entry within the initial cluster that indicates whether the file consists of further clusters, and if so, where on the disk they are located. The operating system directs that clusters continue to be read and their information transmitted to RAM until the last cluster in the chain is read (no further chaining is indicated).

Optical Storage – Read With A Laser �CD-R Compact disk-recordable �CD-RW Compact disk-rewritable DVD-R Digital video disk recordable DVD-RW Digital video disk recordable Blu-Ray Explained

Optical Disks Spiraling Track Detector Pit Land Sector Less sensitive to environment Cheaper than magnetic disks Large data capacity Spins at Constant Linear Velocity

Solid State Drives �No moving parts �More resistant to shock and vibration �Less Power Usage �Faster Data Access �Higher Reliability Solid State Drives Explained

Backing Up Files USB 2. 0 USB Portable Hard Drives and Gadgets USB 3. 0 Using Win. SCP (Windows) Using Fugu (Mac) Backup methods: Full Selective Modified files only