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 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 capacity of the drive you choose is up to you. Generally you should buy the largest capacity drive you can afford. We recommend at least a 1TB drive. This is true especially when you like to download a lot.
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 spin from 5400 to 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 30GB to 512GB. The cost per gigabyte is also much higher with SSDs. Using an SSD for your C drive where Windows and your most used programs are installed is a great way to boost your computer’s performance. In this case we recommend a 120GB SSD at a minimum.
Most SSD come in a 2.5” form factor, while desktop hard drives are 3.5”. The 2.5” form factor allows SSDs to be installed easily into laptops. To install a 2.5” SSD into a desktop a 2.5” to 3.5” adapter is required. Some computer cases come with mounts for 2.5” SSDs and some SSDs will come with this adapter. The adapter can be bought separately for 3 to 5 dollars.
Hard drives and SSDs connect 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 III controllers are becoming standard on new 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 or SSD 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 or SSD 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.
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. Using hard drives this gives you around a 15% increase in performance. Using SSDs you get a 100% increase in performance for each drive you add. 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, when using hard drives, in reading data from the drives. When used with SSDs you get a 100% increase in read speed. The downside to this is that you’re using 2 hard drives and only getting the space of one. So if you have 2, 1TB drives you’re only getting 1TB 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. With 3 hard drive in the array the performance increase over using single drives is between 15% to 25%. With 3 SSDs in the array the performance increase is around 250%.
External Hard drives
There are also hard drives that connect from the outside of the computer called External Hard drives. They come with a 3.5” or 2.5” hard drives inside the case. The 3.5” models can have larger capacity drives and are not as portable, with a separate power adapter required. The 2.5” models are much smaller and lighter and get their power from the USB cable. USB 2.0 and 3.0 are the most popular connection types. You can also find external drives with Firewire, e-SATA and Thunderbolt connections. You can customize your own external hard drive by buying the enclosure and hard drive separately, putting the drive together yourself.
So when you go to purchase your hard drive or drives, you’re looking for…
- At least a 1TB drive capacity for hard drives and at least 120GB for SSDs.
- 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 install the drives into the case.
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.
Hard drive Reviews
- Neoseeker Hard drive Reviews
- Tom’s Hardware Guide Hard drive ReviewsTo 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.