[comp.arch] file systems

royg@ibmpa.UUCP (Roy Gordon) (05/18/89)

Can anyone point me to references, or have ideas, concerning
files systems or other disk management systems that:

	1.  allow sparse disk objects, e.g. files.

	2.  Have a quick lookup for whether a given block is
	    present in a sparse disk object.

	3.  Have a fast access method for retrieving the given
	    block.  

Clearly, Unix file systems satisfy (1) but can fail on (2) and (3)
if the file offset would require double or triple indirection to
determine its presence (and its block # for access).

(2) and (3) are not equivalent.  (2) requires a fast method for
determining if a given block in the sparse object is present,
but not necessarily a fast method for determining where a
given block is.

Thanks in advance.

			-- Roy

			   uunet!ibmsupt!royg
			   (415) 855-4415

Usual disclaimers + not an employee of IBM.  (However, replies
can be to this account.)