I've heard about and read about RAID throughout the years and understand it theoretically as a way to help e.g. server PCs reduce the chance of data loss, but now I am buying a new PC which I want to be as fast as possible and have learned that having two drives can considerably increase the perceived performance of your machine.
"RAID-0 alternates data on two (or more) drives to double (or more) the speed of read access. But this speed comes at the cost of a HIGHER risk of losing your data since if either drive fails, all your data is lost.
RAID-1 mirrors your data by writing a copy on both drives which results in a LOWER risk of losing your data, but it doesn't usually read any faster.
If you have 4 drives, then you can get the best of both worlds by using RAID-10 which is really RAID 1+0, ora mirrored data set (RAID 1) which is then striped (RAID 0).
You may also have heard of RAID-5 which lots of servers use because it not only stripes data but saves parity info as well so that any single drive can fail, and all the data will be safe and can be reconstructed onto a blank drive when the failed drive is replaced.
However, now that terabyte drives are becoming common, the statistical likelihood of an error on a drive is so high, due to the large amount of data, that there is a serious risk of failure of RAID-5 systems where a second drive goes before the first one can be replaced. It's mainly an issue in systems with small numbers of drives, less than 8 or so.
The solution? Use RAID-10 and it turns out that RAID-10 is faster than the fancy RAID-5 since no parity calculations are needed.
So for a fast development machine, I strongly suggest using RAID-10 so that you get all the speed benefits of striping without risking your data. Have a look at this article which also has a nice diagram of RAID-10 that is currently missing from the Wikipedia article. And note that going to 4 drives, may only double your storage, but it increases your read time by four times! If you use a compiled language then you will see almost all of that four times increase in faster compiles."
"If I wanted a developer machine, where I do my development work on it, I'd want something reliable - so I'd go for RAID 1, where any data written is copied to your second drive.
This way, there's an exact copy of everything in your first drive, so if your first drive fails, you can switch over to your second drive and your system will feel like nothing went wrong at all.
But if you're still keen on going for speed then RAID 0 is like this:
You have two drives, drive1 and drive2.
You write a file, say, of 1MB, to your desktop. Now, when your RAID controller receives the file to write to the drives, it'll split your file into half - 0.5MB and 0.5MB, and write each of that into the respective drives, resulting in half the time needed to write the file.
And vice-versa when you're reading out the file. 0.5MB is taken from drive1 and 0.5MB is taken from drive2, so you get the file in half the time (in theory) than you would with only one drive. (We're not delving into random read access times yet)
So that is a super simplified version of RAID 0 and 1.
I personally run my Windows 7 installation on RAID 0 (2x 250GB), and I can vouch for the performance increase in write times. I installed Adobe Master Collection CS3, Full Suite, in about 1-2 minutes, compared to my old system with just a single 7200rpm drive, which took about 5+ minutes."
"So in plain English, how can ""RAID-0"" help me build a faster Windows-7 PC that I am going to order next week?
Unless you need lots of disk space for video editing: Do not use RAID-0. Instead spent the money for the second drive on a small SSD (80GB' ish).
If you want to use it, then thi sis the simplest explanation I can give:
Imagine a secretaty writing or reading froma book. Her speed is limited.
Now if you had two secretaries and two books then you could double the speed, but in practice most of the time one of them would be idle and the other would be hard at work. (E.g. read a chapter from one of the books will mean that the secretary with the book is reading as fast as she can, while the other has nothing to do).
Here is where we try to be clever with RAID 0: We alternate each word. Word 1 is in the first book, word 2 in the second book, word 3 in the first book, word 4 in the second, ....
Now when you read a chapter from the array both secretaries are busy. In theory you double your performance.
That is the least technical explanation I can give. Slightly more technical but very good is this answer on out sistersite."
What RAID 0 does is basically have half of your data on one drive, and half on the other. What sucks is if 1 drive dies you lose all of the data. Do frequent backups. It basically doubles speed in some aspects, and stays the same in others.
