HP StorageWorks 1000 Modular Smart Array installation guide
27
NOTE:
For detailed information about the different RAID levels, see the array configuration
reference guide. This guide is available on the Documentation CD and on the Technical
documentation page of the MSA1000 website:
http://www.hp.com/go/msa1000
.
Hard drive sizes and types
Hard drives in each enclosure and included in the same array should be the same size and type.
When drive sizes and types are mixed within a storage enclosure, the usable capacity and the
processing ability of the entire storage sub-system is affected.
When hard drives of different types or sizes are included in the same enclosure, the processing
characteristics of the entire enclosure are reduced to that of the slowest and smallest drive.
When hard drives of different sizes are included in a LUN, the LUN defaults to the smallest
individual drive size and capacity in the larger drives is unused.
Spare drives
HP recommends including spare drives in your LUNs.
Spares are hard drives that are not active members of any particular LUN, but have been configured
to be used in the event that a drive in one of the LUNs should fail. If a spare is present and a
physical hard drive fails, the spare automatically replaces the failed drive as a member of the LUN
and the process of rebuilding the information onto the spare automatically begins. The system uses
the mirrored or parity information from the other member drives to reconstruct the data onto the
spare.
Array sizing (capacity)
When planning for optimal file-serving performance, you must determine the number of hard drives
necessary to maintain an optimum performance level.
As a general rule, the greater the number of drives that are included in an array, the greater the
performance level that can be achieved. However, the performance considerations are offset by
fault tolerance considerations—the greater the number of drives in an array, the higher the
probability of one or more failures in that array.
RAID 6 (ADG)
Data striping, with two sets of
distributed parity data
Low
High
Medium
* Drives in the array need to be striped across separate enclosures on different SCSI buses.When drives are
selected for an array, the controller always mirrors the first half of the drives selected to the second half of the
drives selected. Therefore, if the drives selected are on a different SCSI bus or in a different enclosure, the
maximum fault tolerance levels will be realized.
Table 4
RAID level comparison
RAID level
Alternative name
I/O
performance
Fault tolerance Storage
efficiency
Summary of Contents for 201723-B21 - HP StorageWorks Modular SAN Array 1000 Hard Drive
Page 58: ...Installation procedures All deployments 58 ...
Page 64: ...Configuration procedures Windows environments 64 ...
Page 70: ...Configuration procedures Linux environments 70 ...
Page 76: ...Configuration procedures HP UX environments 76 ...
Page 82: ...Configuration procedures OpenVMS environments 82 ...
Page 94: ...Configuration procedures Other environments 94 ...
Page 98: ...Powering off and powering on the MSA 98 ...
Page 104: ...Electrostatic discharge 104 ...
