Lesson 1- Hard drive component, building your own computer
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Overview
In lesson 1 we'll cover SATA, IDE, external and SSD hard drives, what features and specs to look for when shopping, and how much you can expect to pay when building your own computer.
The hard drive is where all information is stored on your computer. Be it the Windows operating system, programs you install, or files you download and create on the computer. Everything is stored on the hard drive.
When selecting a hard drive to install into your computer there are two basic features you need to consider. They are the capacity and the speed of the drive.
Capacity:Capacity is how much data a hard drive can store. Capacity is measured in Giga Bytes and Tera Bytes. 1 GB is made up of 1000 Mega Bytes. 1 TB is made up of 1000 GB. To give you an example of how much you can fit into 1 GB of hard drive space, take a MP3 audio file. The average MP3 audio file takes up 5 MB. Divide 1000 by 5 and you get 200. So 1 GB of hard drive space can store 200 MP3 music files. A 1 TB hard drive, which is 1000 GB can store 200,000 MP3 music files.
The size of the drive you choose is up to you. Generally you should buy the biggest drive you can afford. We recommend at least a 1TB drive.
Speed:The speed of the hard drive is determined by the revolution speed of the disk inside the hard drive and the amount of memory cache included in the drive.
The rotation speed is measured in RPMs or revolutions per minute. Most hard drive spins at 7200 revolutions per minute. Faster hard drives spin at 10000 or 15,000 RPMs. The revolutions speed is important because the faster the drive rotates, the more quickly data can be written to and read from, the hard drive.
10,000 and 15000 RPM drives are expensive and the capacities are limited. We recommend buying a 7200RPM drive
The memory cache helps to speed up the accessing of the information on the drive and the more of it the better. Drives can have 64 MB or more of cache. When purchasing a hard drive, a minimum of 32 MB of cache is recommended.
Solid State Drives
Solid-state Drives or SSDs have no spinning disk to store data on. All information is kept on flash memory chips and can be written to and read back much quicker than from a disk based drive. Compared to disk based drives SSDs have lower capacities of between 8GB to 512GB. The cost per gigabyte is also much higher with SSDs.
Larger solid state drives are coming and you can expect the cost per gigabyte to drop, but disk based drives will continue to be the most popular do to their far greater storage capacity.
Interfaces:
The hard drive connects to the computer through the hard drive controller on the motherboard. The most common hard drive controller is called Serial ATA or SATA. Sometimes pronounced say-ta or sa ta. An SATA controllers speed is measured in Mega Bytes or MB per second. The original form of SATA had a speed of 150 MBps.
SATA II controllers which are found on all motherboards today have a speed of 300 MBps.
SATA II also introduced a few new features. The most important is called Native Command Queing or NCQ which speeds up the access of data a little bit more. SATA III controllers are beginning to appear on motherboards. SATA III has a maximum speed of 600 MBps. SATA III is backwards compatible with SATA I and II
To get the maximum speed of SATA III, both the motherboard and the hard drive itself have to support SATA III.
An older hard drive controller types, IDE, sometimes called ATA with speeds that topped out at 133 Mbps is being phased out and will become less available on future motherboards.
We recommend buying a SATA II or SATA III hard drive for your new computer.
Check the specifications on the motherboard, before purchasing, for SATA II or SATA III support. See the motherboard component lesson or the installation lessons for more on motherboards.
See the motherboard component lesson or the motherboard installation lesson for more on motherboards.
What is RAID
There is also a feature on most new motherboards called RAID. RAID allows you to connect 2 or more hard drives together so they show up as 1 drive in Windows. There are three kinds of RAID Arrays. RAID 0, 1 and 5.
RAID 0: Sometimes called Striping, spreads the data across 2 or more hard drives. This gives you around a 15% increase in performance. The downside to RAID 0 is that if just 1 of the drives in the RAID 0 Array fails you will loose all of your data, even on the hard drives that are still working because a portion of your data was on the drive that is now dead. If you use RAID 0 make sure you have your important data backed up off the RAID 0 Array.
RAID 1: Sometimes referred to as Mirroring, uses 2 hard drives and keeps the same data on both drives. This give you a built in backup at all times and gives you around a 15% to 50% performance increase in reading data from the drives. The downside to this is that you're using 2 hard drives and only getting the space of one. So if you have 2 250GB drives you're only getting 250GB of hard drive space.
RAID 5: Combines the striping of data in RAID 0 with the built in backup of RAID 1. 3 or more drives in a RAID 5 array keeps the usable data on 2 thirds of the drives combined space with 1 third of the drives space used as the redundant or Parity data. If one of the hard drives dies it can be replaced with a new drive and the remaining data on the other 2 drives is used to recreate the missing data and get the RAID 5 array back to a fully working state with no data loss. The performance increase over using single drives is between 15% to 25%.
External Hard drives
There are also hard drives that connect from the outside of the computer called External Hard drives. They have their own power supply, separate from the computer and connect through either FireWire, External SATA or USB 2.0 external interfaces. Which is useful if you need to take large amounts of data with you, on the go.
So when you go to purchase your hard drive or drives, you’re looking for...
- At least a 1TB drive capacity.
- At least a 7200 RPM speed with 32MB of cache.
- Serial ATA II or SATA III support.
- If you want to try RAID look for your type of RAID support 0, 1 or 5 on the motherboard.
In the installation lessons we’ll go over how to configure and install your hard drive or drives in your computer.
Hard drive Warranties
Hard drives are generally very reliable and will last for many years. That said, it's best to buy a hard drive with at least a 3 year warranty.
This level of warranty is standard for 7,200 RPM drives with 32MB of cache. Drives with less cache and slower rotation rates typically have a 1 year warranty.
| Manufacturer Links |
| Hitachi/IBM |
| Samsung |
| Seagate |
| Western Digital |
Hard drive Reviews
To find more reviews do a search in your favorite search engine (Google, Yahoo) for the model number of the hard drive you're interested in.
Buying a Hard drive
There is no shortage of choices when buying a hard drive. Below are several sites that will help you find the lowest price from a reputable merchant.
Buy Home PC Builder 2010, for as low as $19.95
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written by Owen, January 15, 2010
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