IBM N Series, Hardware Manual

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IBM System Storage N series Hardware Guide
System and firmware NDU support for stretch MetroCluster
Minor and major version NDU is supported in a stretch MetroCluster environment. Stretch
MetroCluster is essentially an HA pair configuration, so the same limits and qualifications
apply.
System and firmware NDU support for fabric MetroCluster
Minor version NDU is supported for fabric MetroCluster environments.
Major version NDU for fabric MetroCluster is supported from Data ONTAP 7.2.4 (and later) to
Data ONTAP (7.3.2) and later.
20.1.7 System commands compatibility
The cf takeover -f command cannot be used across minor releases. The download process
requires a clean shutdown of the storage controller for the new kernel image to be installed
correctly. If the shutdown is not clean, the system reboots with the old kernel image.
The cf takeover -n command also cannot be used across minor releases. The cf takeover
-n command applies only to major version NDU. It fails if attempted during a minor NDU or
normal takeover.
The
cf giveback -f
command can be used during system NDU. Running this command
might be necessary when long-running operations or operations that cannot be restarted are
running on behalf of the partner.
20.2 Shelf firmware NDU
The IBM N series disk shelves incorporate controller modules that support firmware upgrades
as a means of providing greater stability or functionality. Because of the need for
uninterrupted data I/O access by clients, these firmware updates can, depending on the
model of module that is involved, be performed nondisruptively.
The N series storage controllers, with integrated SAS disk drives, employ internal SAS
expander modules that are analogous to controller modules on stand-alone shelves. At the
time of this writing, these controllers include the N3300, N3600, and N3400 series controllers.