EMC QLA22xx User Manual

Introduction

The current restrictions for boot-from-array configurations (listed in 
the EMC Support Matrix) represent the maximum configuration that 
is allowed using typical configurations. There are cases where your 
applications, host, array, or SAN may already be utilized to a point 
when these maximum values may not be achieved. Under these 
conditions, you may wish to reduce the configuration from the 
maximums listed in the EMC Support Matri, for improved 
performance and functionality. 

Here are some general measurements than can  be used to determine 
if your environment may not support the maximum allowed 
boot-from-array configurations:

◆

Using the Windows Performance Monitor, capture and analyze 
the Physical Disk and Paging File counters for your boot LUN. (For 
Windows NT 4.0, you might have to enable disk performance 
counters manually; refer to Microsoft support for the description 
and use of the Windows Performance Monitor.) If response time 
(sec/operation), or disk queue depth seem to be increasing over 
time, you should review any additional loading that may be 
affecting the boot LUN performance (HBA/SAN saturation, 
failovers, ISL usage, etc.).

◆

Use available Array Performance Management tools to determine 
that the array configuration, LUN configuration and access is 
configured optimally for each host.

Possible ways to reduce the load on the boot LUN include:

◆

Move application data away from the boot LUN.

◆

Reduce the number of LUNs bound to the same physical disks.

◆

Select an improved performance RAID type.

◆

Contact your EMC support representative for additional 
information.