PowerScale OneFS 9.3.0.0 CLI Administration Guide

Usage

This command runs on a single node and iterates through all shadow stores serially. The command starts by retrieving the defragmentation global configuration from gconfig and then resets all of the boolean options to false. Use command line options to enable (re-enable) each of the options as needed.

Syntax

isi_sstore defrag [-a] [-b] [-c] [-d] [-e percent]
[-h] [-l level] [-p] [-s] [-v] [-z  size]
[sins]

Options

-a

Runs the shadow store defragmenter in assessment mode.

Assessment mode generates an estimate of the disk space savings that could occur with defragmentation without actually performing the defragmentation. This mode does not move any data or make any other on-disk changes. This is a quick operation that can be used to determine if the defragmentation feature should be fully enabled. The assessment mode must be turned off for the defragmentation process to do any actual work.

-b

Runs the defragmenter against block-based stores.

BSINs are block-based shadow stores, which are stores used by clone and dedupe operations. The defragmentation process on BSINs can be intensive and may take some time.

-c

Runs the defragmenter against containers.

CSINs are small file storage efficiency containers.

-d

Enables defragmentation. This option is always required, even when running the defragmenter in assessment mode.

-e percent

Sets the target efficiency percentage.

The target_efficiency determines the minimum acceptable storage efficiency relative to the maximum storage efficiency achievable by the shadow store based on its current protection level.

A target of 90% is relatively easy to achieve with a large cluster. The value can be set even higher. Smaller clusters, such as a 3-node cluster, may perform better with a lower target, such as 80%.

The percent is a whole number. If a fraction is specified, the digits after the decimal point are ignored.

The installed global configuration value is 90.

For example: -e 95

-h

Displays the command help.

-l level

This parameter is currently not used.

-p

Enables protection group efficiency.

This is a compaction feature. When enabled, this option attempts to reduce the number of protection groups needed by the shadow stores, which in turn reduces restripe time.

-s

Determines whether the defragmenter examines snapshot files for references to the shadow store being defragged. Consider the following:

• When this option is disabled, if snapshot files contain references to shadow store blocks that need to be defragmented, the defragmenter can not move those blocks and the shadow store may remain fragmented.
• When this option is enabled, it can add significant processing overhead for clusters with many snapshots.

Depending on your workflow, it may be preferable to run the defragmenter most frequently without examining files from snapshots, with occasional runs that include the snapshot files.

-v

Sets the output to verbose.

-z size

Sets the defragmentation chunk size, in bytes. The chunk size is the size of each region in the shadow store that is independently evaluated for defragmentation. The optimal size depends on your workflow.

• Setting a value greater than the size of the shadow store (for example, 2GB), forces the entire shadow store to be defragmented only when the efficiency of the entire store is degraded.
• Setting a small value (for example, 1MB) achieves more aggressive gains.

The installed global configuration value is 33554432 which is 32MB. This setting works well in most scenarios.

sins

Provide an optional list of SINs, separated with spaces, on which to apply this command. The default is to include all SINs.

Examples

The following is sample output for isi_sstore defrag -d -b . The command runs the defragmenter on all BSINs without moving files in snapshots.

# isi_sstore defrag -d -b   
Summary:
    Shadows stores total: 1
    Shadows stores processed: 1
    Shadows stores with error: 0
    Chunks needing defrag: 1
    Estimated space savings: 8192K
    Files moved: 2
    Files repacked: 0
    Files missing: 0
    Files skipped: 0
    Blocks needed: 3072
    Blocks rehydrated: 4096
    Blocks deduped: 2048
    Blocks freed: 4096
    Shadows stores removed: 1

The following is sample output for isi_sstore defrag -d -a -b -v . The command runs the shadow store defragmenter in assessment mode. The output shows the disk space that would be reclaimed by defragmenting all block-based shadow stores.

# isi_sstore defrag -d -a -b -v
Configuration:
    Defrag enabled: 1
    BSINs enabled: 1
    CSINs enabled: 0
    Chunk size: 33554432
    Target efficiency: 90
    PG efficiency: 0
    Snapshots enabled: 0
    Log level: 5
Summary:
    Shadows stores total: 1
    Shadows stores processed: 1
    Shadows stores skipped: 0
    Shadows stores with error: 0
    Chunks needing defrag: 1
    Estimated space savings: 8192K 

The following command requests defragmentation on a list of SINs.

# isi_sstore defrag -v -d -a -c -p 
4000:0001:0000:0001 
4000:0001:0000:0002 
4000:0001:0000:0003 
4000:0001:0000:0004 
4000:0001:0000:0005