Help Me Choose: RAID Configuration

Raid Configuration 12G
 

Level/Description

Fault Tolerance

Advantage

Disadvantage

RAID 0

Maps data across the drives to create large virtual disks. Provides improved performance because each physical disk handles only part of the request. However, one drive failure makes the VD inaccessible and the data is lost permanently.

None
  • Improved performance
  • Additional storage
  • Should not be used for critical data
RAID 1

Mirrors data, where data is stored redundantly across two drives. If one disk fails, the other takes over and functions as the primary drive.

Disk errors

Single disk failures

  • High read performance
  • Fast recovery after drive failure
  • Data redundancy
  • High disk overhead
  • Limited capacity
RAID 5

Maps data across drives and stores parity bits for each data stripe on different drives in the VD. Parity bits contain information that enables a disk’s data to be recreated from the remaining disks in the event of single disk failure.

Disk errors

Single disk failures

  • Efficient use of drive capacity
  • High read performance
  • Med-to-High write performance
  • Disk failure medium impact
  • Longer rebuild due to parity recalculation
RAID 6

Maps data across drives and stores parity bits for each data stripe on different drives in the VD. Unlike RAID 5, RAID 6 makes two parity calculations — P & Q — enabling it to withstand dual disk failures.

Disk errors

Dual disk failures

  • Data redundancy
  • High read performance
  • Write performance decrease due to dual parity calculations
  • Extra cost due to 2 disk equivalent devoted to parity
RAID 10

Stripes over mirrored sets. High disk overhead, but excellent solution for those requiring high performance & redundancy plus the fastest recovery in the event of drive failure.

Disk errors

One disk failure per mirrored set

  • High read performance
  • Supports largest RAID group of 192 drives
  • Most expensive
RAID 50

Stripes over RAID 5 sets. A performance increase over RAID 5 may be realized, depending on the configuration, due to fewer disk reads per parity calculation.

Disk errors

Single disk failure per span

  • High read performance
  • Med-to-High write performance
  • Supports largest RAID group of 192 drives
  • Disk failure medium impact
  • Longer rebuild due to parity recalculation
RAID 60

Stripes over RAID 6 sets. A performance increase over RAID 6 may be realized, depending on the configuration, due to fewer disk reads per parity calculation.

Disk errors

Dual disk failure per span

  • High read performance
  • Supports largest RAID group of 192 drives
  • Write performance decrease due to dual parity calculations
  • Extra cost due to 2 disk equivalent devoted to parity

Go to 'Overview' tab in www.dell.com/perc  for general information. Datasheets and Users Guide are also available on right rail for more detailed information.