# File Destination Defrag

Specifies a maximum batch size used by the destination defrag feature.

Destination defrag improves store file performance by maintaining contiguous space for new messages, while improving server read performance. When persistent pending messages begin to accumulate in a queue, messages are grouped into a batch that is re-written to disk. Messages are written close together, allowing the server to read them more efficiently when later delivering the messages to consumers.

Specify size in bytes, KB, MB or GB.

The size should be set to a size that is known to be acceptable for the disk where the store points to. For instance, if it is set to 2 MB, your disk must be able to write a 2 MB batch efficiently.

If File Destination Defrag is zero or absent, the destination defrag feature is disabled.

## Classic Configuration

Set the destination defrag size using the file_destination_defrag property in the stores.conf file:

    file_destination_defrag=size

For details on the syntax of stores.conf, see File-Based Store Settings.

## Administration Tool

Stores cannot be created or modified using the administration tool.

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