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1992-04-03
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S A F E P A C K
===============
The SAFE Disk Defragmenter
User Manual
CONTENTS
========
Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
Why May Your Disk Need to be Defragmented? . . . . . . . . . 2
Why Safety is Important in a Defragmenter . . . . . . . . . . 3
Requirements & Limitations . . . . . . . . . . . . . . . . . 4
Usage Procedure for SAFEPACK . . . . . . . . . . . . . . . . 5
Swap Files . . . . . . . . . . . . . . . . . . . . . . . 6
SAFEPACK Options . . . . . . . . . . . . . . . . . . . . . . 6
Sorting Options . . . . . . . . . . . . . . . . . . . . 7
Individual File vs Sub-directory Based Sorting . . . . . 8
Sorting Optimizations . . . . . . . . . . . . . . . . . 8
Directory Sorting . . . . . . . . . . . . . . . . . . . 9
Immobile Files . . . . . . . . . . . . . . . . . . . . . 9
Running from the Command Line Only . . . . . . . . . . . 11
Miscellaneous Options . . . . . . . . . . . . . . . . . 11
Registration & Support . . . . . . . . . . . . . . . . . . . 12
Payment . . . . . . . . . . . . . . . . . . . . . . . . 13
Disclaimer - Agreement . . . . . . . . . . . . . . . . . . . 14
_______
____|__ | (R)
--| | |-------------------
| ____|__ | Association of
| | |_| Shareware
|__| o | Professionals
-----| | |---------------------
|___|___| MEMBER
D J Harvey
Copyright (C) 1992 D.J.Harvey. All Rights Reserved.
--- SAFEPACK Manual --- Page 1 ---
Introduction
============
SAFEPACK reorganizes the files on a disk, moving them around as
necessary to ensure that each file occupies a single, contiguous
block of disk space, improving the effective performance of the
drive. Apart from this improvement in speed, many users will
benefit from the collection together of all the free space on the
disk, allowing the creation of large, contiguous special files.
An example of this is a Windows 3 permanent swap file, and the
Windows manual suggests that a disk defragmenter be run before
creating a permanent swap file. No such program is supplied,
however, and SAFEPACK is designed to fill this gap. For the user
who wishes to fine-tune the organization of the disk, a large
number of options are provided to control the final arrangement of
the files.
As its name implies, SAFEPACK has been designed with data security
as the most important principle, and it manipulates the disk file
structures such that they are all valid at all times. This means
that no loss of data should occur if the program is interrupted
while running, whether this be due to user break-in, machine
malfunction, or even power failure.
SAFEPACK is distributed as 'Shareware', which means that though
you are free to evaluate and distribute the program, anyone
intending to make continued use of it must register with the
author, and pay the appropriate fee, which for a single user is
nine pounds Sterling. Credit/charge cards are accepted, removing
the need for currency conversions. Full registration details are
given below, and in the file REGISTER.DOC.
Why May Your Disk Need to be Defragmented?
==========================================
If you are fully conversant with the problem of disk
fragmentation, and know exactly why your disk needs to be
defragmented, you can skip this section, and go to the following
section on safety.
In order to understand why a program such as this is required, it
is necessary to understand just a little about how DOS actually
stores files on a disk. Although users generally refer to files
simply by their path & filename, DOS must allocate space for each
file on the disk, and be able to keep track of where each file is.
Is does this by dividing the disk into a number of 'Allocation
Units' or 'Clusters', normally of 512, 1024, 2048 or 4096 bytes,
and when a file is written, DOS allocates as many unused clusters
as are necessary to accommodate it. Where possible, DOS uses
consecutive clusters, as this improves the speed of both reading
and writing, but this is not always possible, especially after a
--- SAFEPACK Manual --- Page 2 ---
disk has been in use for some time, as the unused clusters may be
scattered around the disk in locations previously occupied by
files which have since been deleted.
An example may make this clearer:
Suppose a very small disk with 18 clusters has 6 files, named F1-
F6 on it, and that they are located as in the following map:
Cluster: |1 2 |3 4 5 |6 7 |8 9 10 11 12|13 14|15 16|17 18
File: | F1 | F2 | F3 | F4 | F5 | F6 | FREE
If files F1, F3 & F5 are now deleted, the map becomes:
Cluster: |1 2 |3 4 5 |6 7 |8 9 10 11 12|13 14|15 16|17 18
File: |FREE | F2 |FREE | F4 |FREE | F6 | FREE
There are now 8 free allocation units, and if a file requiring 7
units called F7 were to be written to this disk, it would have to
be put into the free space, which is spread over the disk, making
the new map:
Cluster: |1 2 |3 4 5 |6 7 |8 9 10 11 12|13 14|15 16|17|18
File: | F7 | F2 | F7 | F4 | F7 | F6 |F7|FREE
File F7 is now said to be fragmented, making access to it
significantly slower than if it were in one contiguous section.
Over time, similar fragmentation occurs to many of the files on a
disk, reducing the effective performance of the drive. This
process happens slowly, however, so the gradual degradation in
drive performance is likely to go un-noticed for a long time.
SAFEPACK reorganizes the files on the disk, amalgamating the
scattered parts of each file, restoring the disk to its original
speed.
Why Safety is Important in a Defragmenter
=========================================
As described above, SAFEPACK moves most of your data from one part
of your disk to another, and this takes quite a long time
(typically 2-30 mins depending on machine, disk size etc). During
such an interval there is clearly the possibility of a failure of
either the power supply or of the machine, and it is important to
consider what would happen to the valuable data on the disk if
this were to happen. Some commercial defragmenters can wreck the
file structure of a disk if they are interrupted, but SAFEPACK has
been designed, as its name implies, to be tolerant of
interruptions, and should leave your disk in a fully usable
condition, even if switched off in the middle. SAFEPACK achieves
this by ensuring that the file structures are valid at all times
during the run, and though this may slow the program down
--- SAFEPACK Manual --- Page 3 ---
slightly, what is an extra few minutes running time, compared with
havi