System Ndu; Types Of System Ndu; Supported Data Ontap Upgrades - IBM N Series Hardware Manual

20.1 System NDU

System NDU is a process that takes advantage of HA pair controller technology to minimize
client disruption during an upgrade of Data ONTAP or controller firmware.
Attention: Because of the complexity and individual clients environments, always see the
release notes and the upgrade guide available for your new Data ONTAP release before
any upgrades.
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/hosts.
The controller for each node in the HA pair configuration is connected to both 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 performing an NDU, 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 at:
http://www.ibm.com/support/docview.wss?uid=ssg1S7003776

20.1.1 Types of system NDU

There are two types of system NDUs: Major and minor:
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 documented in Table 20-1 on page 265.
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 are things that 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

20.1.2 Supported Data ONTAP upgrades

Support for system NDU differs slightly according to the protocols that are in use on the
system. The following sections address those different protocols.
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IBM System Storage N series Hardware Guide