Jump to content

Block allocation map

Edit links
From Wikipedia, the free encyclopedia
This is an old revision of this page, as edited by Hydradix (talk | contribs) at 05:10, 5 February 2013 (add link to block availability map, described block allocation in CP/M, link to CP/M). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

In computer file systems, a block allocation map (BAM) is a data structure used to track disk blocks that are considered "in use".


CP/M used an allocation map in its directory. Each directory entry could list 8 or 16 blocks (depending on disk format) that were allocated to a file. If a file used more blocks, additional directory entries would be needed. Thus, a single file could have multiple directory entries. This method also allowed sparse files to be created by declaring a large file size but only allocating blocks that are actually used.

See also


Stub icon

This computer-storage-related article is a stub. You can help Wikipedia by expanding it.

Retrieved from "https://en.wikipedia.org/w/index.php?title=Block_allocation_map&oldid=536643096"