IBM N Series, Hardware Manual

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IBM System Storage N series Hardware Guide
Support for deduplication and compression
You can perform major and minor nondisruptive upgrades when deduplication and
compression are enabled. However, avoid active deduplication processes during the planned
takeover or planned giveback. Consider the following points:
򐂰 Perform the planned takeover or giveback during a time when deduplication processes are
not scheduled to run.
򐂰 Determine whether any deduplication processes are active and, if so, stop them until the
planned takeover or giveback is complete.
You can turn the operation off and on by using the sis off and sis on commands. Use the
sis status command to determine whether the status of deduplication is Active or Idle. If a
deduplication process is running, the status of deduplication is Active.
If there is more than the allowable number of FlexVol volumes with deduplication enabled, sis
undo must be run. This command undoes deduplication and brings the number of FlexVol
volumes to within the limit for that version of Data ONTAP. The sis undo command can be a
time-consuming process, and requires enough available space to store all blocks that are no
longer deduplicated. Run the
sis undo command on smaller volumes and volumes with the
least amount of deduplicated data. This process helps minimize the amount of time that is
required to remove deduplication from the volumes.
For more information about deduplication and compression volume (dense volume) limits for
NDU, see 20.1.4, “System NDU software requirements” on page 284.
20.1.3 System NDU hardware requirements
System NDU is supported on any IBM N series storage controller, or gateway, hardware
platform that supports the HA pair controller configuration. Both storage controllers must be
identical platforms.
Systems must be cabled and configured in an HA pair controller configuration. This
configuration includes all InfiniBand interconnect cables, correct NVRAM slot assignments,
and appropriate controller-to-shelf cabling, including (as applicable) multipath high-availability
storage and SyncMirror configuration options.
20.1.4 System NDU software requirements
Predictable takeover and giveback performance is essential to a successful NDU. It is
important 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 accurately
predict 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 the
customer has an N7900 HA pair controller configuration that is installed with Data ONTAP
7.3.3 and wants to perform a nondisruptive upgrade to 8.0.1, the number of FlexVol volumes
that are supported per controller is limited to 500.
Regardless of the system limits, run a system with processor and disk performance usage no
greater than 50% per storage controller.