3.0 - Architecture and Design Flashcards
1
Q
What does RAID stand for?
A
- redundant array of inexpensive disks
2
Q
What are the levels of RAID?
A
- RAID-0
- RAID-1
- RAID-5
- RAID-6
- RAID-10
3
Q
What is RAID-0?
A
- RAID-0 (also called striping) does NOT provide ANY redundancy or fault tolerance
- files stored on a RAID-0 array are spread across each of the disks
- the benefit of RAID-0 is increased read and write performance
- because a file is spread across multiple physical disks, the different parts of the file can be read from or written to each of the disks at the same time
- you combine drives for RAID-0 (3x 500GB drives means you have 1.5TB of storage space)
4
Q
What is RAID-1?
A
- RAID-1 (also called mirroring) uses two disks
- data written to one disk is also written to the other disk
- if one of the disks fails, the other disk still has all the data
- provides redundancy by mirroring the data identically on two hard disks
5
Q
What is RAID-5?
A
- RAID-5 is three or more disks that are striped together similar to RAID-0
- the equivalent of one drive includes parity information
- this parity information is striped across each of the drives and is used for fault tolerance
- if one of the drives fails, the system can read the information on the remaining drives and determine what the actual data should be
- if two drives fail in RAID-5 then the data is lost
- provides redundancy by striping data and parity data across the disk drives
6
Q
What is RAID-6?
A
- RAID-6 is an extension of RAID-5 and it includes an additional parity block
- a huge benefit is that the RAID-6 disk subsystem will continue to operate even if two disk drives fail
- RAID-6 requires a minimum of 4 disks
- provides redundancy by striping and double parity data across the disk drives
7
Q
What is RAID-10?
A
- RAID-10 combines the features of mirroring (RAID-1) and striping (RAID-0)
- the minimum number of drives in RAID-10 is four and you must add multiples of 2 for extra drives
