HP D3000 Disk Enclosures - Manual (Page 22)

Storage planning considerations include:
•
System and performance expectations
•
Striping methods
•
RAID levels
•
Disk drive sizes and types
•
Spare drives
•
Array sizing (capacity)
NOTE: For the minimum supported configuration, and other configuration information, see the
QuickSpecs for the disk enclosure.
System and performance expectations
To help determine the best way to configure your storage, rank the following three storage
characteristics in order of importance:
•
Fault tolerance (high availability)
•
I/O performance
•
Storage efficiency
With priorities established, you can determine which striping method and RAID level to use; some
configuration methods offer greater fault tolerance, while other configuration methods offer better
I/O performance or storage efficiency.
Striping methods
There are two methods for configuring the physical layout of the disk arrays:
•
Vertical striping—the RAID array uses one physical drive from each disk enclosure.
•
Horizontal striping—the RAID array uses multiple drives contained within one or more disk
enclosures.
RAID levels
Controllers use RAID technology to group multiple disk drives together in larger logical units (LUNs).
Key RAID methods include the use of data striping, data mirroring, and parity error checking. Data
striping improves speed by performing virtual disk I/O with an entire group of physical disks at
the same time. Mirroring provides data redundancy by storing data and a copy of the data. Parity
error checking provides automatic detection and correction if corruption of a physical disk occurs.
Depending on the host environment, the following RAID levels are supported with this disk enclosure:
RAID0, RAID1, RAID5 and RAID6 with ADG. Each level uses a different combination of RAID
methods that impact data redundancy, the amount of physical disk space used, and I/O speed.
After you create a LUN, you cannot change the RAID level.
The following table compares the different RAID levels.
RAID method Data redundancy Best practices Summary
Striping None IMPORTANT: Do not use RAID0 for
LUNs if fault tolerance is required. RAID0 is optimized for I/O
speed and efficient use of RAID0
Consider RAID0 only for noncritical physical disk capacity, but
provides no data redundancy. storage. RAID0 LUNs provide the
best performance for applications
that use random I/O.
Mirroring High In general, RAID1 virtual disks
provide better performance RAID1 is optimized for data
redundancy and I/O speed, RAID1
22 Installation