Specifications

NetApp Deduplication for FAS and V-Series Deployment and Implementation Guide

impact will be experienced on low-end systems (for example, 30xx) more than high-end systems (for

example, 6xxx).

In takeover mode, writes to partner flexible volumes will be change logged. The deduplication process

will not run on the partner flexible volumes while in takeover mode. Upon giveback, data in the change

logs will be processed, and data will get deduplicated.

In takeover mode, change logging will continue until the change log is full. This can occur if the node

remains in takeover mode for a long period of time, such as a disaster. All data will continue to be

accessible regardless of change log availability.

A node in takeover mode will take over the servicing of I/Os targeted at the partner volumes, as well as

its change logging. As a result, additional system resources will be consumed, which may require that

the system workload be appropriately adjusted.

Only a subset of deduplication commands for the partner volumes are available in takeover mode. For a

list of these commands, see section ―Deduplication and Active-Active Configuration.‖

Deduplication must be licensed on both nodes.

For additional information regarding MetroCluster, refer to TR-3548, MetroCluster Design and

Implementation Guide.

4.14 DEDUPLICATION AND DATAFORT ENCRYPTION

If implementing DataFort encryption and NetApp deduplication for FAS, the following items should be taken

into consideration:

Encryption removes data redundancy. As a result, encrypted data usually yields extremely low amounts

of capacity savings.

Deduplication can be run on encrypted data, but capacity savings are expected to be 0%.

Since encryption can be run at the share level, it is possible to create a flexible volume where only part

of the data on the volume is encrypted. If deduplication is run on such a volume, 0% capacity savings is

expected on the encrypted data, but it will still be possible to deduplicate the rest of the volume

effectively.

4.15 DEDUPLICATION AND LUNS

When using NetApp deduplication in a file-based (NFS/CIFS) environment, deduplication is straightforward

and automatic; as duplicate blocks are freed, they are marked as available, and the NetApp system

recognizes these free blocks and makes them available to the volume.

Deduplication in a block-based (FCP/iSCSI) LUN environment is slightly more complicated. This is because

of the space guarantees and fractional reservations often used by LUNs. With space guarantees, for

instance, a 500GB LUN that is created consumes exactly 500GB of physical disk space. If the data in the

LUN is reduced through deduplication, the LUN still reserves the same physical space capacity of 500GB,

and the space savings are not apparent to the user.

LUN space guarantees and fractional reserves can be configured so that the use by the NetApp system of

the freed blocks changes depending on the configuration. By varying the values of certain parameters, freed

blocks can be returned to the LUN overwrite reserve, the volume free pool, or the aggregate free pool, or a

combination.

This section describes five common examples of LUN configurations and deduplication behavior, as

summarized in Table 7.