Source: http://communities.netapp.com/docs/DOC-1060
FAQ NetApp Deduplication 08_25_08.pdf
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3. HOW DO I ADD THE DEDUPLICATION CAPABILITY TO A FAS SYSTEM?
Installing the nearstore and a_sis licenses on a supported system will enable the deduplication capability. Although these licenses must be requested by the customer, there is no charge for either license. Note: R200 systems do not required the nearstore license.
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9. IS THERE A MINIMUM DATA ONTAP RELEASE REQUIRED FOR NETAPP DEDUPLICATION?
Yes. NetApp deduplication for FAS requires the installation of Data ONTAP 7.2.4 or greater. NetApp deduplication for V-Series requires Data ONTAP 7.3 or greater.
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21. WHAT PROTOCOLS DOES NETAPP DEDUPLICATION SUPPORT?
NetApp deduplication is independent of protocols and thus supports all NetApp SAN and NAS protocols: iSCSI, FCP, NFS, and CIFS
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22. ARE THERE ANY SPECIAL CONSIDERATIONS IN USING DEDUPLICATION WITH LUNS?
NetApp deduplication operates regardless of protocol. However, LUNs are a somewhat special case because of reservations and space guarantees. The default mode of deduplication and LUNs is to apply any space savings to the snapshot reserve area. However, If LUN space guarantees are disabled, and the snapshot reserve set to zero, LUNs can be deduplicated and “thin provisioned.”
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24. CAN I ESTIMATE MY SPACE SAVINGS BEFORE INSTALLING DEDUPLICATION?
Yes. A space savings estimation tool (SSET) is available to NetApp and Partner SE’s. This tool is a standalone application that operates on a Windows or Linux client and will “crawl” through any NFS volume (up to 2TB) and will estimate the amount of space savings you will get with deduplication.
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25. CAN PREVIOUSLY WRITTEN VOLUME DATA BE DEDUPLICATED?
Yes. NetApp deduplication can scan and deduplicate existing data on a volume. This can be run at any time on a volume that contains previously written data, and is recommended to be run whenever deduplication is first enabled on a volume.
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29. CAN I MANUALLY START AND STOP THE DEDUPLICATION PROCESS?
Yes. You can initiate the deduplication process at any time with a CLI command, and also stop it at any time with a CLI command.
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30. CAN THE DEDUPLICATION PROCESS BE AUTOMATED?
Yes. The default operation of deduplication is to automatically begin deduplication of a volume if a 20% new data change rate is detected since that last time deduplication was run. If the user prefers regularly scheduled or manual deduplication, this automatic feature can be turned off.
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31. HOW OFTEN SHOULD DEDUPLICATION BE RUN ON A VOLUME?
The frequency of deduplication scheduling depends on the frequency that redundant writes are taking place on the volume. Typically, deduplication might be run approximately once per week on the volume. If more frequent redundant writes are taking place, for instance nightly SQL database dumps, then running deduplication more frequently may be recommended.
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33. HOW DO I VERIFY THE SPACE SAVINGS WITH DEDUPLICATION IN A GIVEN VOLUME?
Use the “df –s” command to verify the cumulative space savings per volume. The results are listed in number of blocks and % saved. An example of the output from this command:
> df -s /vol/VolPST Filesystem used saved %saved /vol/VolPST/ 24072140 9316052 28%
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49. CAN I DEMO DEDUPLICATION FROM THE DATA ONTAP SIMULATOR?
Yes. The Data ONTAP 7.3 simulator supports deduplication.
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