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Rethinking the Datacenter
Sponsored by HP
Today's datacenters need to increase utilization, get control over power and cooling costs, and align with business objectives. Download this eBook to learn about the challenges facing the data center in a world where digital information is growing at a torrid pace and costs are being held in check. Learn more. »
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Putting the Green into IT
Sponsored by HP
Electricity use in data centers is skyrocketing, sending energy bills through the roof, creating environmental concerns and generating negative publicity. "Going Green" means looking to technologies like virtualization, energy-efficient chips and racks, and implementing policies that extend beyond the data center. Learn more. »
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Managing the Modern Network
Sponsored by HP
In a global economy where information crosses the globe in an instant, and where Web-based applications power business, it's more important than ever to ensure your network is safe from threats and optimized to deliver the data your business needs. »
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Evaluating Software as a Service for Your Business
Sponsored by Webroot
Is Software as a Service just hype, or is something really going on here? See if your company can benefit as SaaS tries to change the face of the enterprise.
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Is Your Disaster Recovery Plan Good Enough?
Sponsored by HP
Preparing for a disaster is more often than not part of the storage planning process, and it is one of the most difficult tasks, since it includes local hardware and software, networking equipment, and a test plan. Learn how to get disaster recovery right. »
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Linux Partitions: A Primer
Hard Drive Basics

Dee-Ann LeBlanc
Thursday, June 20, 2002 11:19:09 AM
Most computer users are aware of the existence of their hard drive,
even if they're not familiar with how it works. It's hard not to be,
since the first things people tend to ask when you get a new computer
are how much hard drive space you have, how fast the machine is, and
how much memory is included. From there, if you're used to using
Windows, then you've probably dealt with the installer letting you
break your hard drive into "multiple drives," probably referred to as
C:, E:, F:, and so on.
You may not realize it, but if you've done this, you've already
created partitions. A partition is a virtual drive inside a drive,
created through storing information about the drive's virtual layout
in special locations on the drive itself. The system's BIOS and
operating system(s) then utilize this information to determine where
to look on the drive for boot instructions and data.
A hard drive may look like a short, rectangular box, but the data is
stored on a round section that looks somewhat like a stack of records
(see Figure 1). The way data gets written to and read from this drive
involves drive heads, which are housed on the carriage assembly shown
in the image. Each of these electromagnetic heads alters data on a
hard drive by manipulating the magnetic media at such a miniscule
level that the head turns on and off individual bits and bytes.
When a PC boots, once the BIOS finishes loading hardware information,
it looks to the very first spot on the hard drive, which is referred
to as the Master Boot Record (MBR). How do we find this spot? The data
on a hard drive is stored in a series of rings called tracks, and the
tracks are subsequently broken up into equally sized pieces called
sectors (see Figure 2). Tracks are numbered from 0 on up, and the
counting starts at the outermost ring. Sectors are numbered from 1 on
up.
The MBR is on track 0, sector 1: the very first location on the drive.
In this tiny spot on your hard drive, two key pieces of information
live. The first is the data on how many partitions you've created on
the drive, and their vital statistics. The second is vital to whether
your machine will boot properly or not without a floppy disk: the MBR
contains a pointer to the specific partition or hard drive that has
the boot information.
If you're familiar with Linux installation, then you'll know that the
boot loaders LILO and GRUB place information in the MBR.
Next: Partition Basics »