Browse Prior Art Database

Two Phase File Deletion

IP.com Disclosure Number: IPCOM000104421D
Original Publication Date: 1993-Apr-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 124K

Publishing Venue

IBM

Related People

Pipitone, RM: AUTHOR

Abstract

Disclosed is a method to avoid accidential loss of data by not making file deletion dangerously easy and avoiding annoying bothersome dialogues to determine if the file should really be deleted.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 41% of the total text.

Two Phase File Deletion

      Disclosed is a method to avoid accidential loss of data by not
making file deletion dangerously easy and avoiding annoying
bothersome dialogues to determine if the file should really be
deleted.

      The problem of accidental loss of data because file deletion
was too easy and too permanent has existed since interactive
computing began.  The typical solution has been to make the user of
the computer system confirm the pending deletion by entering into an
annoying dialogue to determine if the file should really be deleted.
Such a dialogue brakes the user's stream of conscience, interfering
with the job at hand.  Also, all too often in an effort to end the
dialogue quickly, additional mistakes are made.  Thus, even this
attempt at a solution is error prone.  This method avoids the pit
falls of a too easy file deletion without the annoyance of an
unnecessary dialogue with a computer.

      The basis of this method is to decompose file deletion into two
phases or steps.  The first phase, called the preparation phase,
prepares a file for deletion by altering its directory information to
indicate that it is ready for deletion.  The second phase, called the
removal phase, completes the deletion processes by actually erasing
the file.  The elapsed time between these two phases is expected to
be long by computer standards.  Days, weeks or even months may elapse
between the preparation phase and the removal phase of a file.  To
accomplish this long elapsed time between phases, certain
requirements must be met by the preparation phase.  The requirements
of the preparation phase are:

      The preparation of a file for deletion must be quick and easy.
It must be so safe that the accidental preparation of file for
deletion is of little consequence to the user.  This implies that the
reversal of the preparation process must also be quick and easy.

      A file that has been prepared for deletion must behave as if it
were not there.  After a file has been prepared for deletion it can
not be accessed.  A new file of the same name may be created.

      All actions must be reversible thus allowing the complete
recovery of the file to its original form.

      The simplest implementation of a two phase delete is to mark
the file prepared for deletion and rename it during the preparation
phase.  In the removal phase only files which have been prepared for
deletion are erased.  No dialogues with the user are necessary.  The
new name of the file can be either a generated name or one derived
from the original name.  In either case the association of the new
name with the original name is required to allow for the UNDELETE
operation.

      The preferred method for implementing two phase deletion would
be with the assistance of the underlying file system.  The file
system would define its directory structure such that entries for
individual files would include a prepared-for-delet...