Metadata Preferences


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Treat reserved metadata sizes as hard limits

Normally, iDefrag will try to place the entirety of the Catalog and Extents Overflow B-Tree files inside the metadata zone. However, the zone is sized based on some calculations that include a maximum size for both the catalog file and the extents file. If this option is selected and one or other file exceeds its allotted size, iDefrag will instead split the file into two, placing the remainder immediately following the end of the metadata zone.

The benefit of this option, if it is necessary, is that the adaptive hot file clustering feature of Mac OS X will still be able to function despite the disk containing a larger than expected amount of volume metadata.

Without this option, a disk with over-size catalog and extents files would probably cause the hot file clustering system to shut down due to a lack of free space in the “Hot Band”

Note that you should not normally need to enable this option. It is only intended to be used when necessary.

Compact B-Tree files

If enabled, when running the Metadata or Full Defrag algorithms, iDefrag will attempt to squeeze unused space out of the B-Tree files that are used to keep track of the locations, names and sizes of files (as well as a variety of other information).

Rebuild rather than just compacting

Instead of simply compacting the existing nodes in a B-Tree file, this option causes iDefrag to completely rebuild the B-Tree files before running the compaction routine on them.