What exactly is RAID?
- Thread starter Aecliptica
- Start date
Kanyon
Genesis Torn
Ah, just like using multiple disks at one time in case one fails (redundancy), although not always the case (RAID 0 is just striping with no parity). And also to pull some more speed when reading from the drives (two or three drives transfer data faster than one). But it all depends, For instance the disk mirroring (RAID 1) makes duplicate drives, where on reading either and/or both the disks can be used however when writing to the mirrored array, both disks must each be written to, so the gain in performance is really on the reading, not the writing. However a drive can crap out on you and it can just be replaced - hot swappable usually. Whereas something like RAID 0 which is striping has files spread across both drives where say, a file is read and parts 1,3,5 and 7 come from Disk 1 - parts 2,4,6 and 8 come from Disk2 and so on to make the total file. In this way both disk drive heads are working at the same time to achieve faster times. It would be the same when writing to it too, faster because data needs to be written only once across both disks, unlike the mirroring. However with a striped set, if a drive fails, you are boned.
Then there is stuff like RAID 5 that require at least three drives. Imagine that one disk contains is one set area the data that is the number 5 - the next disk in the same set area is 3 and the final disk has the set area a result of the other two, like 5 + 3 = 8 which is striping with parity, where any given disk can fail and the system can rebuild that disk when replaced based on the remaining data from the other two, so imagine:
5+3=8
Drive a fails x+3=8
Drive b fails 5+x=8
Drive c fails 5+3=x
If any of that badly written mess makes sense?
Thats already a mess though - Cause I couldnt be bothered typing so much, here is a link.
http://www.adaptec.com/worldwide/product/markeditorial.html?prodkey=quick_explanation_of_raid
Then there is stuff like RAID 5 that require at least three drives. Imagine that one disk contains is one set area the data that is the number 5 - the next disk in the same set area is 3 and the final disk has the set area a result of the other two, like 5 + 3 = 8 which is striping with parity, where any given disk can fail and the system can rebuild that disk when replaced based on the remaining data from the other two, so imagine:
5+3=8
Drive a fails x+3=8
Drive b fails 5+x=8
Drive c fails 5+3=x
If any of that badly written mess makes sense?
Thats already a mess though - Cause I couldnt be bothered typing so much, here is a link.
http://www.adaptec.com/worldwide/product/markeditorial.html?prodkey=quick_explanation_of_raid
DE
vote bnp
Basically, it lets you use a set of hard drive as if it was one drive. There are different types, all with different features, with their own pros and cons.
Personally, I don't think RAID 0 or RAID 1 is worth the hassle. I'm going to sort myself out with RAID 5 at the end of the year - you can take one drive out of the array, or have a drive fail, and it still maintains all the data as if you'd never removed it. The only downside is that you lose
total size * (1 / number of drives)
hard drive space, but it's definitely worth it.
Personally, I don't think RAID 0 or RAID 1 is worth the hassle. I'm going to sort myself out with RAID 5 at the end of the year - you can take one drive out of the array, or have a drive fail, and it still maintains all the data as if you'd never removed it. The only downside is that you lose
total size * (1 / number of drives)
hard drive space, but it's definitely worth it.
DE
vote bnp
