Specifications

NetApp Deduplication for FAS and V-Series Deployment and Implementation Guide
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(There are no configurable parameters that can tune the deduplication process; that is, the priority of this
background process in Data ONTAP is fixed.)
IMPACT ON THE SYSTEM DURING THE DEDUPLICATION PROCESS
The deduplication operation runs as a low-priority background process on the system. However, it can still
affect the performance of user I/O and other applications running on the system.
The number of deduplication processes that are running and the phase that each process is running in can
cause performance impacts to other applications running on the system (up to eight deduplication processes
can actively run at any time on a system). The following are some observations made when running
deduplication on a FAS3050 system:
With eight deduplication processes running, and no other processes running, deduplication uses 15% of
the CPU in its least invasive phase, and nearly all the available CPU in its most invasive phase.
When one deduplication process is running, there is a 0% to 15% performance degradation on other
applications.
With eight deduplication processes running, there may be as much as a 15% to 50% performance
penalty on other applications running on the system.
THE I/O PERFORMANCE OF DEDUPLICATED VOLUMES
Write Performance to a Deduplicated Volume
The impact of deduplication on the write performance of a system is a function of the hardware platform that
is being used, as well as the amount of load that is placed on the system.
If the load on a system is low—that is, for systems in which the CPU utilization is around 50% or lower—
there is a negligible difference in performance when writing data to a deduplicated volume, and there is no
noticeable impact on other applications running on the system. On heavily used systems, however, where
the system is nearly saturated with the amount of load on it, the impact on write performance can be
expected to be around 15% for most NetApp systems. The performance impact is more noticeable on
higher-end systems than on lower-end systems. On the FAS6080 system, this performance impact can be
as much as 35%. The higher degradation is usually experienced in association with random writes. Note that
these numbers are for FC drives; if ATA drives are used in a system, the performance impact would be
greater.
Read Performance from a Deduplicated Volume
When data is read from a deduplication-enabled volume, the impact on the read performance varies
depending on the difference between the deduplicated block layout compared to the original block layout.
There is minimal impact on random reads.
Since deduplication alters the data layout on the disk, it can affect the performance of sequential read
applications such as dump source, qtree SnapMirror or SnapVault source, SnapVault restore, and other
sequential read-heavy applications. This impact is more noticeable with data sets that are zero-padded or
data sets that contain blocks with repeating patterns (such as applications that preinitialize data blocks to a
value of zero). Significant performance degradation has been measured in sequential reads with these types
of data patterns. The performance impact is also more significant on sequential reads from SATA drives as
compared to FC drives. Therefore, if an application depends on sequential read performance, the impact of
deduplication on read performance should be carefully considered before implementation.
In cases of random reads on deduplicated volumes, there is usually little impact on performance.
THE PERFORMANCE ACCELERATION MODULE (PAM)
The PAM card is available with Data ONTAP 7.3 and later.
In environments where there are shared blocks that are read repeatedly, the PAM card can help reduce the
number of disk reads, thus improving the read performance.
The amount of performance improvement with the PAM card depends on the duplication rate, the access
rate, the active data set size, and the data layout.
Adding a PAM card to a system does not increase the deduplication maximum volume size for that system.