Compaq StorageWorks HSG60 ACS Solution Software V8.6 for Sun Solaris Installation and Configuration Guide

6–2 HSG60 ACS Solution Software Version 8.6 for Sun Solaris Installation and Configuration Guide
Servers
Servers are the computing power and the communication access to the storage that the
computing applications require. Servers can connect to local storage or RAID Arrays.
Many have tried to characterize the loading of a server in relation to a “number of”
quantities involved in a server-storage relationship.
Commonly described in the loading relationships are considerable factors that include the:
■ Number of adapters on a server, and
■ Number of RAID systems that may be connected to an adapter.
A server may have up to 4 adapters and connect up to 4 RAID arrays. These numbers
represent a relatively safe area of loading and are acceptable for most general usage
server-storage situations. For some servers (e.g., in the 4m class) these values may be too
high and for some servers (e.g., in the 4u class of Enterprise servers) these numbers may
be too low. The maximum number of adapters is only limited by the number of available
expansion slots. We have tested up to 24 adapters simultaneously in a mainframe-class
machine (E10000).
The numbers presented in the previous paragraph, however, do not stand alone when
describing a load on a server-storage system. The key value(s) are the actual I/O loading
from server to storage. The major components of I/O values are:
■ Reading versus writing data
■ The size of the records being read/written
■ The frequency of data to/from a storage device
The following set of major components has a large impact on the viability of a
configuration from the RAID array point of view:
■ The nature of the controller (SCSI versus Fibre)
■ The amount of cache on the controller
■ The configuration of the disks enclosed by the RAID Array.
A specific configuration may or may not replicate the tested laboratory configuration(s).
When treating a specific configuration, the best guideline is to determine the viability of a
configuration that is the best for your environment.
Additionally, while a given configuration may support the desired I/O quantity, it may not
support a desired performance characteristic of the I/O. Thus both configuration and
performance can be best described with some test trials of a specific configuration.