Home > Storage > PowerScale (Isilon) > Product Documentation > Data Efficiency > Dell PowerScale OneFS: Data Reduction and Storage Efficiency > Inline data reduction configuration and management
OneFS inline data reduction uses a simple administrative control plane. Configuration is by the command line interface (CLI), using the ‘isi compression’ and ‘isi dedupe inline’ commands. There are also utilities provided to decompress, or rehydrate, compressed and deduplicated files if necessary. Plus, there are tools for viewing on-disk capacity savings that inline data reduction has generated.
The ‘isi_hw_status’ CLI command can be used to confirm and verify the node(s) in a cluster. For example:
# isi_hw_status –i | grep Product
Product: F810-4U-Single-256GB-1x1GE-2x40GE SFP+-24TB SSD
Since compression configuration is binary, either on or off across a cluster, it can be easily controlled by the OneFS command line interface (CLI). For example, the following syntax will enable compression and verify the configuration:
# isi compression settings view
Enabled: No
# isi compression settings modify --enabled=True
# isi compression settings view
Enabled: Yes
Note: In-line compression is enabled by default on new F810 clusters running OneFS 8.2.1 and later, on new H5600 clusters running OneFS 8.2.2 and later, on new F600 and F200 clusters running OneFS 9.0, on F900 clusters running OneFS 9.2, on H700/7000 and A300/3000 clusters running OneFS 9.2.1 and later, F710 and F210 clusters running OneFS 9.7 and later, and F910 clusters running OneFS 9,8 and later.
In a mixed cluster containing other node styles in addition to compression nodes, files will only be stored in a compressed form on F910, F900, F810, F710, F600, F210, F200, H5600, H700/7000, and A300/3000 node pool(s). Data that is written or tiered to storage pools of other hardware styles will be uncompressed on the fly when it moves between pools. A non-inline compression supporting node on the cluster can be an initiator for compressed writes in software to a compression node pool. However, this may generate significant CPU overhead for lower powered nodes, such as the A-series hardware and provide only software fallback based compression with lower compressibility.
While there are no visible user space changes when files are compressed, the ‘isi get’ CLI command provides straightforward method to verify whether a file is compressed. If compression has occurred, both the ‘disk usage’ and the ‘physical blocks’ metric reported by the ‘isi get –DD’ CLI command will be reduced. Also, at the bottom of the command’s output, the logical block statistics will report the number of compressed blocks. For example:
Metatree logical blocks:
zero=260814 shadow=0 ditto=0 prealloc=0 block=2 compressed=1328
For more detailed information, the –O flag, which displays the logical overlay, can be used with the ‘isi get’ command. This command is described in more detail later in this paper.
OneFS inline data compression can be disabled from the CLI with the following syntax:
# isi compression settings modify --enabled=False
# isi compression settings view
Enabled: No
Since inline deduplication configuration is binary, either on or off across a cluster, it can be easily controlled by the OneFS command line interface (CLI). For example, the following syntax will enable inline deduplication and verify the configuration:
# isi dedupe inline settings view
Mode: disabled
# isi dedupe inline settings modify –-mode enabled
# isi dedupe inline settings view
Mode: enabled
Note: In-line deduplication is enabled by default for new clusters running OneFS 9.4 or later. For earlier OneFS releases, inline dedupe is disabled by default
While there are no visible user space changes when files are deduplicated, if deduplication has occurred, both the ‘disk usage’ and the ‘physical blocks’ metric reported by the ‘isi get –DD’ CLI command will be reduced. Also, at the bottom of the command’s output, the logical block statistics will report the number of shadow blocks. For example:
Metatree logical blocks:
zero=260814 shadow=362 ditto=0 prealloc=0 block=2 compressed=0
OneFS inline data deduplication can be disabled from the CLI with the following syntax:
# isi dedupe inline settings modify –-mode disabled
# isi dedupe inline settings view
Mode: disabled
OneFS inline data deduplication can be paused from the CLI with the following syntax:
# isi dedupe inline settings modify –-mode paused
OneFS inline data deduplication can be run in assess mode from the CLI with the following syntax:
# isi dedupe inline settings modify –-mode assess