284 IBM System Storage N series Hardware GuideSupport for deduplication and compressionYou can perform major and minor nondisruptive upgrades when deduplication andcompression are enabled. However, avoid active deduplication processes during the plannedtakeover or planned giveback. Consider the following points: Perform the planned takeover or giveback during a time when deduplication processes arenot scheduled to run. Determine whether any deduplication processes are active and, if so, stop them until theplanned takeover or giveback is complete.You can turn the operation off and on by using the sis off and sis on commands. Use thesis status command to determine whether the status of deduplication is Active or Idle. If adeduplication process is running, the status of deduplication is Active.If there is more than the allowable number of FlexVol volumes with deduplication enabled, sisundo must be run. This command undoes deduplication and brings the number of FlexVolvolumes to within the limit for that version of Data ONTAP. The sis undo command can be atime-consuming process, and requires enough available space to store all blocks that are nolonger deduplicated. Run the sis undo command on smaller volumes and volumes with theleast amount of deduplicated data. This process helps minimize the amount of time that isrequired to remove deduplication from the volumes.For more information about deduplication and compression volume (dense volume) limits forNDU, see 20.1.4, “System NDU software requirements” on page 284.20.1.3 System NDU hardware requirementsSystem NDU is supported on any IBM N series storage controller, or gateway, hardwareplatform that supports the HA pair controller configuration. Both storage controllers must beidentical platforms.Systems must be cabled and configured in an HA pair controller configuration. Thisconfiguration includes all InfiniBand interconnect cables, correct NVRAM slot assignments,and appropriate controller-to-shelf cabling, including (as applicable) multipath high-availabilitystorage and SyncMirror configuration options.20.1.4 System NDU software requirementsPredictable takeover and giveback performance is essential to a successful NDU. It isimportant not to exceed Data ONTAP configuration limits.Table 20-3 on page 285 shows the limits per storage controller for FlexVol, dense volumes,Snapshot copies, LUNs, and vFiler units. These parameters are essential to accuratelypredict when a planned takeover or planned giveback completes during the NDU process.The limits are identical for N series controllers and gateways.These limits are based on the destination version of DATA ONTAP. For example, if thecustomer has an N7900 HA pair controller configuration that is installed with Data ONTAP7.3.3 and wants to perform a nondisruptive upgrade to 8.0.1, the number of FlexVol volumesthat are supported per controller is limited to 500.Regardless of the system limits, run a system with processor and disk performance usage nogreater than 50% per storage controller.
