HP AA HP Netserver 4000 Reference Guide

HP NetServer AA
Hewlett-Packard Company
5-2
Before Upgrading the HP AA System
Adding components to an existing HP AA Array is not as simple as
adding components to a standalone system. Many considerations
must be taken into account to ensure the array experiences no
downtime or at least the minimum downtime necessary for the
action.
One of the primary considerations when performing many system
upgrades is the decision to maximize uptime in lieu of a disk re-
mirror or sacrifice the downtime to avoid a disk re-mirror.
Most system upgrades are easily be accomplished by bringing down
the system, making the changes and bringing the system back online.
If the customer can tolerate the downtime this is always the least
complicated method of upgrading system components. However,
many customer environments cannot tolerate the downtime. When
this occurs a methodical approach must be taken to ensure the least
amount of downtime is encountered.
In addition to downtime considerations, care must be taken to avoid
bringing down a functioning array by mis-configuring a device
during the upgrade process. The following sections will examine the
steps necessary to perform a variety of upgrade functions.
Becoming Familiar With the Array
When encountering a HP AA Array the configuration of the array
may not be familiar. It is critical that time be taken to become
acquainted with the array before beginning any system upgrades.
Even if the array is familiar it is prudent to pause for a few minutes
to reflect on the task to be accomplished, the steps to complete the
task and the effects of each of those steps on the availability of the
system.
A firm knowledge of the following is necessary before beginning
any upgrade.
• Identify the CEs and the IOPs.
• Know the display method used.
• The network configuration, including what adapters are
performing the role of IL and what adapters are public rail
adapters.
• The disk structure, including the location of IOP and CE boot
disks.
• What devices on the IOP are redirected.
• What devices are mirrored.
• What RAID structure is used.