Sunday, 28 August 2011

Hard drive choices

Hard Drives
Choosing your hard drive;
What differentiates one hard drive from another? if we take a couple of screen shots from a computer store, I will explain the varying factors that should help you make the correct 

capacity: 500GB - This is simply your capacity (the amount of data you can store), so the more the merrier right ?
16MB Cache - The cache is a seperate memory chip on the controller board of the hard drive. Hard drives (the magnetic type) are by their nature quite slow when you consider the speed at which SATA  controllers can handle - 600MB/s (6Gb/s). You would be lucky to get 150MB/s with a regular magnetic hard drive - this is where the solid state hard drives come in which we will cover later. If the hard drive had to feed the processor data on the fly it would be a terrible experience.  So basically - more cache means more performance.
SATA III (6Gb/s) - as mentioned above - not to be mistaken with GB/s 6 Giga bits per second! I did chuckle when I was speaking to a friend and they referred to it as 6 Giga Bytes per second - that really would be some epic data rates. To be honest you would have to run a number of these drives in a RAID 0 configuration to capitalise on the 6Gb/s bandwidth capacity. If you are unsure of RAID then Google it. I am not going to explain how to set up a RAID in a beginners guide.

7200RPM - The speed at which the disk spins. The faster the disk spins, the less time that the armature has to wait for the data to come back around after a full revolution presuming that it just missed the data as it span round. - The higher the RPM - the better the data rates, however you will find that with faster RPM drives, more gains are to be had when reading smaller files.
you will be able to get 10kRPM hard drives on the SATA interface (Western Digital's Velociraptor's).  Anything above that, you start looking at the SCSI drives intended for $erver$.
Well that about covers the 'standard' hard drives. At the time of writing this blog, solid state hard drives are relatively new technology in this form in the tech market.
A solid state drive is basically like RAM. Silicon chips on a board which store data. This is a much faster form of accessing and storing data however at this moment in time, there are still teething problems such as people losing all their data. Not only are there serious problems covering a whole array of drives (currently the finger is pointing at the SandForce controller chip). Hopefully for those who have spent some serious cash on these drives, there will be a simple work around such as a firmware update. Having said all that, the fact that you can pick up a hard drive for around £30 for 500GB -  I personally will wait until all the problems have been ironed out before joining on the SSD bandwagon.

There are yet another type of drive known as hybrid drives, as you would expect by the name, are an amalgamation of the aforementioned disk types - magnetic and solid state.
These drives combine the relatively cheap storage option of the magnetic disk and also add some high speed SSD into the works, which in turn offers a reasonably priced high speed option. Once again though, I would personally not touch this type of storage option due to its new place in the market, as with any new technology there are usually teething problems which need sorting, however what you choose is entirely up to you, just make sure that you do some research beforehand to find all the pros and cons.

You also need to be aware that SATA and IDE are two different types of hard drives - molex power + IDE cable as opposed to SATA data cable and SATA power. SATA being the only sensible choice for a new build.
Speaking simplisticly, the IDE will have an IDE cable (looks like a flat cable, quite wide however very thin; the SATA uses a very narrow and thin cable. Other than just looking much tidier in the case, the SATA hard drives come with higher speed drives, more data bandwidth - basically just a step in the right direction with new technology. 
Unless your motherboard does not support SATA (which it should do) I would steer clear from IDE drives. - You will also need to make sure that your power supply comes with SATA power plugs.

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