IBM N Series, Hardware Manual

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Chapter 20. Designing for nondisruptive upgrades
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20.3.1 Overview of disk firmware NDU
Beginning with Data ONTAP 7.0.1, nondisruptive disk firmware upgrades occur automatically
in the background. This process occurs when the disks are members of volumes or
aggregates of the following types:
򐂰 RAID-DP
򐂰 Mirrored RAID-DP (RAID-DP with SyncMirror software)
򐂰 Mirrored RAID 4 (RAID 4 with SyncMirror software)
Upgrading disk firmware on systems that contain nonmirrored RAID 4 containers (volumes or
aggregates) is disruptive, and can occur manually or during reboot only. In Data ONTAP 7.2
and later, disk firmware updates for RAID 4 aggregates must complete before Data ONTAP
can finish booting. Storage system services are unavailable until the disk firmware update
completes.
The underlying feature that enables disk firmware NDU, called
momentary disk offline
, is
provided by the option raid.background_disk_fw_update.enable option. This option is set
to On (enabled) by default.
Momentary disk offline is also used as a resiliency feature as part of the error recovery
process for abnormally slow or nonresponsive disk drives. Services and data continue to be
available throughout the disk firmware upgrade process.
Beginning with Data ONTAP 8.0.2, all drives that are members of RAID-DP or RAID 4
aggregates are upgraded nondisruptively in the background. Still, upgrade all disk firmware
before a Data ONTAP NDU is done.
20.3.2 Upgrading the disk firmware non-disruptively
Nondisruptive upgrades are performed by downloading the most recent firmware from the
IBM Support site to the controller’s
/etc/disk_fw directory. Updates start automatically for
any disk drives that are eligible for an update. Data ONTAP polls approximately once per
minute to detect new firmware in the
/etc/disk_fw directory. Firmware must be downloaded
to each node in an HA pair configuration. During an automatic download, the firmware is not
downloaded to an HA pair partner's disks.
Automatic disk firmware upgrade
Background disk firmware updates do not occur if either of the following conditions are
encountered:
򐂰 Degraded volumes exist on the storage system
򐂰
Disk drives that need a firmware update are present in a volume or plex that is in an offline
state
Updates start or resume when these conditions are resolved.
Make sure that the process occurs automatically. Do not manually use the disk_fw_update
command. Set systems with large numbers of disks to upgrade automatically overnight. If the
option raid.background_disk_fw_update.enable is set to On (enabled), disk firmware
upgrade occurs automatically only to disks that can be brought offline successfully from active
file system RAID groups and from the spare pool.