Chapter 20. Designing for nondisruptive upgrades 29120.3.1 Overview of disk firmware NDUBeginning with Data ONTAP 7.0.1, nondisruptive disk firmware upgrades occur automaticallyin the background. This process occurs when the disks are members of volumes oraggregates 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 oraggregates) is disruptive, and can occur manually or during reboot only. In Data ONTAP 7.2and later, disk firmware updates for RAID 4 aggregates must complete before Data ONTAPcan finish booting. Storage system services are unavailable until the disk firmware updatecompletes.The underlying feature that enables disk firmware NDU, called momentary disk offline, isprovided by the option raid.background_disk_fw_update.enable option. This option is setto On (enabled) by default.Momentary disk offline is also used as a resiliency feature as part of the error recoveryprocess for abnormally slow or nonresponsive disk drives. Services and data continue to beavailable throughout the disk firmware upgrade process.Beginning with Data ONTAP 8.0.2, all drives that are members of RAID-DP or RAID 4aggregates are upgraded nondisruptively in the background. Still, upgrade all disk firmwarebefore a Data ONTAP NDU is done.20.3.2 Upgrading the disk firmware non-disruptivelyNondisruptive upgrades are performed by downloading the most recent firmware from theIBM Support site to the controller’s /etc/disk_fw directory. Updates start automatically forany disk drives that are eligible for an update. Data ONTAP polls approximately once perminute to detect new firmware in the /etc/disk_fw directory. Firmware must be downloadedto each node in an HA pair configuration. During an automatic download, the firmware is notdownloaded to an HA pair partner's disks.Automatic disk firmware upgradeBackground disk firmware updates do not occur if either of the following conditions areencountered: 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 offlinestateUpdates start or resume when these conditions are resolved.Make sure that the process occurs automatically. Do not manually use the disk_fw_updatecommand. Set systems with large numbers of disks to upgrade automatically overnight. If theoption raid.background_disk_fw_update.enable is set to On (enabled), disk firmwareupgrade occurs automatically only to disks that can be brought offline successfully from activefile system RAID groups and from the spare pool.
