kraid: What is RAID and what does it mean?

Data Striping:

• By mounting two hard disks in such a mode, they will be controlled (either by a hardware chip or by software) in a way that the two drives are combined into a single volume which will be twice the size of the smaller HD (that's way it is preferrable when adopting this solution to pair together two identical in size HDs).
  
• Data will be split equally on each disk; i.e.: if you were to save an 80Kb file to the disk, the first 8Kb will be recorded on disk A, then the next 8Kb will be recorded on disk B, and so on.
  
• The result will be a much efficient way to retrive and record data on magnetic media as you have available two different hard drive mechanism that work together on the same data.
  
• Such method returns up to 50% increase in data throughput rates under both reads and writes activities.
  
• This kind of RAID system is often used when for the end user data transfer speed is crucial for his own productivity (e.g. video management applications, sound playback and recording apps, photo and image manipulations in general, heavy duty DataBase activity, etc....).
  
• The drawback of such solution, however, is that if one of the disks fails it would be very difficult to retrive any data at all (in a way "reduntant" is the wrong word for such setup). In this case a proper, well planned and consistent, backup strategy is essential for safe operations.
  
• Due to the high levels of reliability modern hard disk drives have reached in recent times, more and more users tend to apply this solution to improve their own work efficiency: installing such a RAID setup in your own machine may result a lot cheaper than purchasing a more modern, bigger and faster computer.
  

Disk mirroring:

• In this case the two hard disks work as indipendent volumes from one another.
  
• The first disk works normally as any other disk you usually see on computers.
  
• The second disk operates as 'the dormient' one by instantly and automatically copying everything and anything is happening on disk 1.
  
• The benefit of such solution is that if anything goes wrong with disk 1, such as a disk failure, disk 2 can take over operation as if nothing has happened. The user will hardly notice any difference.
  
• The drawbacks of such solution are that even the following will be instantly and automatically copied on drive 2:
  
  • Accidental deletes
    
  • Viruses
    
  • Corrupted data
    
  • Etc....
    
  
  
• In addition, disk access on writes is somewhat slowed down as Disk 2 mechanism will hold up the OS availability untill the write activity on such disk is over.