IBM N Series, Hardware Manual

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IBM System Storage N series Hardware Guide
20.1 System NDU
System NDU is a process that uses HA pair controller technology to minimize client disruption
during an upgrade of Data ONTAP or controller firmware.
System NDU entails a series of takeover and giveback operations. These operations allow
the partner nodes to transfer the data delivery service while the controllers are upgraded.
This process maintains continuous data I/O for clients and hosts.
The controller for each node in the HA pair configuration is connected to its own storage
shelves and the storage shelves of its partner node. Therefore, a single node provides access
to all volumes and LUNs, even when the partner node is shut down. This configuration allows
each node of HA pair controllers to be upgraded individually to a newer version of Data
ONTAP or firmware. It also allows you to transparently perform hardware upgrades and
maintenance on the HA pair controller nodes.
Before an NDU is performed, create an NDU plan. For more information about developing an
NDU plan, see the Data ONTAP 8.1 7-Mode Upgrade and Revert/Downgrade Guide, which is
available at this website:
http://www.ibm.com/support/docview.wss?uid=ssg1S7003776
20.1.1 Types of system NDU
The following types of system NDUs are available:
򐂰
Major
A major version system NDU is an upgrade from one major release of Data ONTAP to
another. For example, an upgrade from Data ONTAP 7.2.x to Data ONTAP 7.3.x is
considered a major system NDU.
Major version NDU is supported only when going from one release to the next in
sequence. There are occasionally exceptions when deemed necessary to bypass a major
release in an upgrade sequence. For example, customers are allowed to nondisruptively
upgrade from 7.3 to 8.1 without having to upgrade to 8.0 as an interim step. These
exceptions are shown in Table 20-1 on page 283.
򐂰 Minor
A minor version system NDU is an upgrade within the same release family. For example,
an upgrade from Data ONTAP 7.3.1 to Data ONTAP 7.3.2 is considered a minor system
NDU. The following characteristics constitute a minor version system NDU:
– No version number change to RAID, WAFL, NVLOG, FM, or SANOWN
– No change to NVRAM format
– No change to on-disk format
– Automatic takeover must be possible while the two controllers of the HA pair are
running different versions within the same release family
Attention: Because of the complexity and individual clients environments, always see the
release notes and the upgrade guide that is available for your new Data ONTAP release
before any upgrades.