Recommended disk array configurations, Configuration considerations – HP Surestore Disk Array 12h and FC60 User Manual
Page 77
Recommended Disk Array Configurations 77
T
opo
logy
and
Ar
ra
y
Pla
nnin
g
Recommended Disk Array Configurations
This section presents recommended configurations for disk arrays using one to six disk
enclosures. Configurations are provided for achieving high availability/high performance,
and maximum capacity. The configuration recommended by Hewlett-Packard is the high
availability/ high performance configuration, which is used for factory assembled disk
arrays (A5277AZ). The configurations identify the number of disk enclosures, cable
connections, disk enclosure bus modes, RAID level, and LUN structure.
Most of the configurations offer the highest level of availability, which means they are
capable of surviving the failure of a single disk (provided LUNs are created with one disk
module per disk enclosure), SCSI channel, disk enclosure, or controller module. The only
configurations that do not offer the highest level of availability are the single disk enclosure
configuration, and the two enclosure high capacity configuration. These configurations
cannot survive the failure of an entire disk enclosure, so they should not be used in
environments where high availability is critical.
The configurations list maximum disk capacity and usable disk capacity (with ten disk
modules installed). Configurations based on RAID 1 have less usable disk capacity than
RAID 5, but I/O performance is optimized when using RAID 1. Although the recommended
configurations presented here all contain ten disk modules, a disk enclosure can contain
four, eight, or ten disk modules.
Note
The terms “LUN” and “volume group” are used interchangeably in the text and
figures in this section.
Configuration Considerations
The following factors should be considered when using any of the recommended
configurations.
•
Multiple Hosts - A single host system is shown, but configurations can be adapted to
create multi-host, high availability systems. For more information on using multiple
hosts, see
"Topologies for HP-UX" on page 102
or