Week_3 - © 2008 Purdue University Marcus K. Rogers CIT 1...

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Unformatted text preview: © 2008 Purdue University Marcus K. Rogers CIT 1 Computer Forensics: Basics Lecture 5 Disk Structures and Controlled Boot Environment © 2008 Purdue University Marcus K. Rogers CIT 2 Outline • Disk Structure – Magnetic Based HDs – Flash Memory Drives – Solid State Drives • Calculating Disk Capacity • Controlled Boot Environment © 2008 Purdue University Marcus K. Rogers CIT 3 Learning Objectives • At the end of this module you will be able to: – Describe the basics of disk structures – Explain how information is stored on a magnetic drive – Determine the storage capacity of drive using LBA or CHS © 2008 Purdue University Marcus K. Rogers CIT 4 Disk Structure • Hard disks drives (magnetic based) are organized as a concentric stack of disks or ‘platters’ • Each platter has 2 surfaces © 2008 Purdue University Marcus K. Rogers CIT 5 © 2008 Purdue University Marcus K. Rogers CIT 6 © 2008 Purdue University Marcus K. Rogers CIT 7 HD Structure • Rigid disk surface • Head-disk assembly must be sealed & micro-filtered • Multiple platters increase storage without equivalent increase in cost © 2008 Purdue University Marcus K. Rogers CIT 8 HD Head Clearance © 2008 Purdue University Marcus K. Rogers CIT 9 © 2008 Purdue University Marcus K. Rogers CIT 10 Laptop HD © 2008 Purdue University Marcus K. Rogers CIT 11 Disk Structure • The data is stored on concentric circles on the surfaces known as tracks • Corresponding tracks on all platter surfaces make up a cylinder • The cylinder can be written to without movement of the head assembly • Numbering starts with 0 at the outermost cylinder © 2008 Purdue University Marcus K. Rogers CIT 12 Sector • A sector is a continuous linear stream of magnetized bits occupying a curved section of a track. • Sectors are the smallest physical storage units on a disk- Each sector stores 512 bytes of data • Numbering physical sectors within a track starts with 1. Sector 1 Track 0 Sector 2 Track 0 © 2008 Purdue University Marcus K. Rogers CIT 12 Sector • A sector is a continuous linear stream of magnetized bits occupying a curved section of a track. • Sectors are the smallest physical storage units on a disk- Each sector stores 512 bytes of data • Numbering physical sectors within a track starts with 1. Sector 1 Track 0 Sector 2 Track 0 © 2008 Purdue University Marcus K. Rogers CIT 13 One Sector (not to scale) Sync Area Header Data Area CRC Value For Timing Contains CHS Address Error Correction 512 Bytes of Storage Sector Structure Each sector actually has four major segments : – Synchronization bytes – Sector address – User data area (512 bytes) – The CRC area is for error correction Corruption of any of these areas will generate an error Actual size = 571 bytes © 2008 Purdue University Marcus K. Rogers CIT 14 Cluster (Blocks) • 1 or more contiguous sectors • The smallest pieces of storage that an OS can place into data • The bytes in a cluster (Block) varies according to the...
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This note was uploaded on 02/29/2012 for the course CNIT 420 taught by Professor Dr.marcrogers during the Spring '12 term at Purdue University.

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Week_3 - © 2008 Purdue University Marcus K. Rogers CIT 1...

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