Administrator Guide

Data Reduction Methods
Data reduction is supported on a per-NAS-volume basis to store data more eciently. The Dell FluidFS cluster supports two types of
data reduction:
• Deduplication — Performed on qualied data when data reduction is enabled on a container. You cannot disable deduplication
when data reduction is enabled. Deduplication (or dedupe) provides data reduction by eliminating redundant copies of data
across les in a volume by keeping only one copy of unique deduplicated data. When the data is read, it is uncompressed and
rehydrated in memory to its original form. The data on the disk remains unchanged.
NOTE: Deduplication is enabled by default. It activates when you enable data reduction, because it is part of the data
reduction process. The Deduplication option shows as being enabled even when Enable data reduction is
not yet selected.
• Compression — Uses a Level Zero Processing System (LZPS) compression algorithm on already deduplicated data to further
enhance data reduction. The next time the data is accessed, it is uncompressed and rehydrated, thereby returning to its original
form. (To utilize this feature, when you create the NAS volume, rst enable data reduction and then enable compression.)
Data Reduction and Snapshot Reserve
The snapshot reserve functionality enables you to reserve a maximum percentage of disk storage space for snapshots. When a
snapshot is created, it serves as a pointer to the data contained within the NAS container. It does not write to or consume any space
in the snapshot reserve until the data is modied or deleted from the container.
The oldest snapshots autodelete in the following instances:
• The data written to the snapshot reserve exceeds the amount of reserved space.
• The number of scheduled snapshots exceeds the specied maximum number of snapshots to keep (max-keep).
The max-keep guideline does not apply to manually created snapshots, only to scheduled snapshots. Manually created snapshots can
coexist with scheduled snapshots. They can also be autodeleted when the snapshot reserve space consumed exceeds the amount
of reserved space if data reduction is not enabled.
The snapshot reserve functionality is permanently disabled after data reduction is enabled, even if data reduction is later disabled on
the container. When you enable data reduction on a container, the only way to automatically delete snapshots when running a
snapshot schedule is to dene a maximum number of snapshots to retain for that schedule.
All other snapshot actions are supported after data reduction is enabled, as shown in Table 47. Data Reduction Eect on Snapshots.
Table 47. Data Reduction Eect on Snapshots
Supported Snapshot Actions Before Data
Reduction
After Data
Reduction
Manually create snapshots Yes Yes
Manually delete snapshots Yes Yes
Automatically create snapshots using snapshot schedules Yes Yes
Automatically delete snapshots when a maximum number of snapshots is exceeded Yes Yes
Automatically delete snapshots when a maximum percentage of container space (snapshot
reserve) is exceeded
Yes No
Yes: Enabled No: Disabled
Enable Data Reduction
You must be logged in as grpadmin to enable data reduction on an existing NAS container.
1. Click NAS, expand NAS Clusters and Local Containers, and then select the NAS container name.
2. In the Activities panel, click Modify settings to open the dialog box.
NAS Container Operations
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