RAID - Redundant Array of Independent Disks
Friday, June 27th, 2008RAID allows the system to read or write to multiple disks at once as though they were one single disk. There are a few flavors, some are redundant (RAID 1) some are faster (RAID 0) and some are redundant and faster (RAID 1+ 0 or RAID 5).
RAID 0 writes and reads different information to/from two drives, so that you can “double” your input and ouput (it’s not exactly doubled, but it’s a vast improvement over a single drive) Basically you can look at it this way - you may be able to suck soda through a straw really fast, but if you have two straws - you can suck twice as much soda in the same amount of time. Although it doesn’t exactly double as there is some overhead, it’s a similar idea for Raid0.
RAID 1 writes and reads the same information to/from two drives, so if one of the two drives fails there is no downtime and the other drive will continue to function. This will not increase read/write speed but it will increase reliability. Basically one hard drive is mirrored to another on the fly, and should one fail the changeover to a single drive is transparent.
What are advantages of RAID?
Reundancy, Speed, or Redundancy+Speed
What are disadvantages of RAID?
If it’s software raid (no hardware controller) the raid overhead can create a CPU load and if it’s being accessed a lot can cause some issues. Generally Hardware raid solutions are not affected by this issue as they have their own processing power built in ot handle the Raid Array, but if it’s “free raid” chances are it’s not hardware.
Faster Server or Slower because of RAID?
If it’s set up with RAID 0 or RAID 5 it could be faster, if it’s software it would be faster most likely but would load the server a bit more during I/O. If it’s hardware and RAID 0 or RAID 5 it would definitely be faster.
