If you’re like me and have been building computers for a while or have collected old computer parts, hard drives in this case, and they are just sitting around; then you may be able to put them to use! Below I’ll be speaking about all the different types of RAID levels as well as a general description of a RAID.
What is a RAID?
A RAID or Redundant Array of Independent Disks is when you take more than one hard drive and combine them into one larger device. For example, taking four 250GB hard drives and creating a RAID can effectively give you a total hard drive space of 1TB. When a RAID is created, depending on which type of RAID level you select, the data written to the drives is written across all drives.
How do I begin a RAID?
To start a RAID you will need to acquire a minimum of two hard drives; these two hard drives can be totally different in the case of RAID 0, 2 and 3. Now you will have to check your motherboard’s manual to find out whether or not your motherboard supports a RAID configuration. Some motherboards may only be able to support certain types of RAID levels.
If your motherboard doesn’t support RAIDs then you will need to buy a RAID PCI controller. These controllers are a much better option than using the motherboard for a RAID setup, however they don’t come cheap. Using the controller takes the stress off the motherboard as the controller will take care of all read and write of the data. It should be noted that if a hard drive does fail while using a RAID controller, hard drive diagnostics, such as Seagate Tools or DataLifeguard, may not be able to read or repair the drives at all.
Most motherboards may also only come with a maximum of four SATA ports, which is the way data is sent to the drives, where a RAID controller may have up to eight slots.
What are the levels of a RAID?
There are seven different RAID configurations to choose from. Each have a different application of how the hard drives will behave.
If you do run using a RAID controller it is possible to run more then one RAID configuration at a time. You just need to meet the minimum required hard drives for each RAID configuration.
RAID 0
We start off with a RAID 0 which is a block-level striping without parity or a mirroring of the drives. The zero in RAID 0 means that the hard drives will have zero redundancy, which provides improved performance and full hard drive capacity of both drives. This is the same example I gave above. The downside of a RAID 0 is that if offers zero protection against a failure on the array. If a hard drive is removed or one dies then all the data across all hard drives is destroyed. The minimum number of hard drives required to run in RAID 0 is two.
RAID 1
Moving on we have RAID 1 which is a mirroring without parity or striping of the drives. Data will be written identically across a minimum of two drives. This in return will give you a mirrored set of the first drive. RAID 1 can only function in match pairs as if four hard drives are added to the array then two drives will be created in a RAID 0 and two will mirror the others. The effects of a mirrored set gives you a failsafe if one drives happens to go under a hardware failure. However the downside of a RAID 1 is that you only get the capacity and performance of one of your drives.
RAID 2 & 3
RAID 2 and 3 are a little bit different than the rest of the RAID levels. When booting up the drives it puts all of the disk spindle rotation in a synchronized stage. Data is striped in such a way that each bit of data is on a different hard drive. This type of RAID level is not typically used and most motherboards don’t even support it.
RAID 4 & 5
RAID 4 is basically equivalent to RAID 5 in that all parity data is stored on one single hard drive. RAID 5 is seen more as a professional setup as it works similarly to RAID 1. RAID 5 requires a minimum of three hard drives to operate. An example would be that if using three hard drives you could have the capacity and performance of two hard drives. Using three drives in RAID 5 takes one of the hard drives and puts it into a reserve. In case of a failure the reserve drive is used to recreate the array with no data lose. The downside of a RAID 5 setup is that without a RAID controller read and write speeds may suffer and recreating a new array may take a long time.
RAID 6
Similar to a RAID 5 fallback, RAID 6 can take a hit on two hard drive failures and yet still function as it should. You will need to acquire a minimum of four hard drives and this setup has a much slower read speed then a RAID 5. RAID 6 also isn’t possible without a high-tech server type setup.
RAID 10
RAID 10 is often seen as a combination of RAIDs 1 and 0 (RAID 1+0). With the minimum of four drives data is written in stripes across the primary drives that have been mirrored to the secondary drives. What’s nice is you get the performance of RAID 0 of two of the drives yet have the safety net of RAID 1 as a mirror of the two primary drives. Just like RAID 6 you can lose up to a total of two hard drives and still function normally. This setup is even offered on most motherboards.
Conclusion
Now many of us may not need to bother with a RAID since hard drives are now available in sizes over 1TB but it does help with other computers or if you do have more than one drive. It should be noted that SSDs can also be placed into a RAID. Hopefully this helps you choose which RAID level is the best for you and stay tuned for more all you need to know articles!
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