Descriptions Of Raid Levels - HP AK373A - StorageWorks All-in-One Storage System 1200r 5.4TB SAS Model NAS Server User Manual

Customizing RAID levels
Before you customize the default RAID level setting, review
levels affect performance, capacity, and data protection level.
Unless you customize the advanced configuration settings, the wizard configures the storage space
with the default values shown on the Advanced window:
• For Exchange and SQL Server, the wizard suggests default settings based on HP storage best
practices and specific recommendations for Exchange storage group and SQL Server database
components. You should generally accept these defaults.
• For user-defined applications and shared folders (where industry-standard recommendations cannot
be determined), the wizard provides default settings you can customize.
Table 22 shows how the different RAID levels affect:
• Performance–The speed at which data is read from and written to the hard drives. The RAID level
with the best performance rating provides the fastest reads and writes.
• Capacity–The available storage space on the hard drives. The RAID levels with the best capacity
rating require the least amount of storage space to store data.
• Data protection–The number of hard drives that can fail without data being lost. The RAID level
with the best data protection rating allows more hard drives to fail before data is lost.
For more information on the different RAID levels, see
Table 22 Descriptions of RAID levels
RAID level
No RAID
RAID 0 – Striping (No Fault Tolerance)
RAID 1 – Mirroring
Table 22
Table 22.
Description
Offers no protection against disk failure. If a disk drive fails, data is
lost.
Offers the greatest capacity and performance without data protection.
If you select this option, you will experience data loss if a hard drive
that holds the data fails. However, because no logical drive capacity
is used for redundant data, this method offers the best capacity. This
method offers the best processing speed by reading two stripes on
different hard drives at the same time and by not having a parity
drive.
Offers a good combination of data protection and performance. RAID
1 or drive mirroring creates fault tolerance by storing duplicate sets
of data on a minimum of two hard drives. There must be an even
number of drives for RAID 1. RAID 1 and RAID 1+0(10) are the most
costly fault tolerance methods because they require 50 percent of the
drive capacity to store the redundant data. RAID 1 mirrors the contents
of one hard drive in the array onto another. If either hard drive fails,
the other hard drive provides a backup copy of the files and normal
system operations are not interrupted.
HP StorageWorks All-in-One Storage System
to see how the different RAID
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