Client Area

Guide to Hard Disks

Description
Disk Space
Performance
Fault Tolerance / Data Protection
Required # of drives
Single Disk – No RAID
One hard disk attached to the local SATA controller of a server. This configuration is the most common. This configuration allows the utilization of all of the physical hard disk’s space, the full performance of the drive, but offers no fault tolerance and off-site backups should be maintained. 		All Full None One
Multiple Disk – No RAID
Multiple hard disks attached to the local SATA controller of a server. This configuration is more common. This configuration allows the utilization of all hard disk capacity, the full performance of all hard disks but offers no automatic fault tolerance and off-site backups should be maintained.		 All Full User can manually or automatically copy files from one disk to another. Two or More
RAID-0
Two hard disks are attached to a hardware RAID controller. The data is spanned across both drives providing increased performance over a single disk. RAID-0 offers no fault tolerance.
Reference: RAID 0 		All Better None Two
RAID-1
Two hard disks are attached to a hardware RAID controller. The data is mirrored between the two drives providing excellent fault-tolerance but slightly reducing performance. The disk space is reduced to half of the combined size of the two drives.
Reference: RAID 1 		Half Good Excellent – Data is mirrored from Active to Backup Two
RAID-10 (RAID-0 + RAID-1)
RAID-10 is a set of four drives connected to a hardware RAID controller. RAID-10 (0+1) is actually a combination of RAID-0 and RAID-1, data is first spanned across a set of two drives and then that set is mirrored to two additional drives. RAID-10 is faster than RAID-1 and offers fault tolerance.
Reference: RAID 10 		The size of the span set. Better Excellent – Data is mirrored from Span set to Mirror Set Four
RAID-5
RAID-5 is a set of four or more drives and is considered a parity set in which ‘bits’ of data are stored on all drives in the RAID set. If a single drive fails the system can continue to operate normally. A hot spare can be configured to recover from a single disk failure to ensure perpetual disk operation.
Reference: RAID 5 		Varies depending on whether a hot spare is configured. Good Excellent – Single Parity (one drive can fail and server can continue to operate) At least four
RAID-6
RAID-6 is a set of four or more drives and is considered a party set in which ‘bits’ of data are stored on all drives in the RAID set. If two drives fail simultaneously the system can continue to operate normally. Multiple hot spares can be configured to recover from multiple simultaneous disk failures to ensure perpetual disk operation.
Reference: RAID 6 		Varies depending on whether hot spare is configured and how many Good Best – Double Parity (two drives can fail simultaneously and server can continue to operate) At least four