[p,pn] - optional, the ppn area at which to start the
operation. PAKIT will skip searching of the
lower ppn's for files to move.
/switches - optional, one or more of the following.
/D - process directory blocks only
/Q - do it in the quick mode
/S - process sequential access files only
/R - process random access files only
At any time in the operation of PAKIT, the program can be
terminated (with partial results realized) by hitting control-C.
Page 2
PAKIT
How It Works
PAKIT consolidates all the free space on the disk by
moving all the sequential access files (text files, programs,
etc.) down to the bottom of the disk and moving all the random
access files (data, libraries, etc.) up to the top. This is the
natural distribution of these two types of files since that is the
way AMOS allocates them when they are created. As you, and your
programs, edit and erase files, gaps appear throughout the disk.
PAKIT fills in those gaps by moving files adjacent to the largest
gap into the smaller gaps. It does this in three phases.
1. It reads all the directories and gathers data for the
packing operation.
2. It moves sequential files down to pack against the bottom
of the disk. Only those files that are too high are
actually moved.
3. It moves random access files up, starting at the highest
random access file, and proceeding on down to the lowest.
Only those files that will move up are actually moved.
Files that are imbedded in the sequential files area are
left there; they are already in a good location.
In phase 1, PAKIT adds up the sizes of all the sequential
files, makes a table of all the random access files, and packs the
directory blocks themselves (including all UFDs and the MFD). In
phase 2, using the "high-water" value calculated from the sizes of
the sequential files as a mark, it moves all sequential access
files that are above that mark down under that mark. Then in
phase 3 it squeezes out the space in the random access files area
by shoving all the random access files up.
Page 3
PAKIT
Optional Modes of Operation
Doing a straight PAKIT, with no switches, as in
PAKIT DSK1:
will consolidate all free space into one contiguous area.
There is nothing else you need to do but wait for it to happen.
There are some faster ways to get adequate results, and we will
describe them here.
1. /D - The /D switch causes PAKIT to operate only on the
directory blocks. It will skip the processing of the
files. Although directories do not occupy very many
blocks on a disk, just one directory block in the middle
of a 400 block space will turn that one large area into
two very much smaller areas. /D will get that block out
of the way. /D will also give you a directory of all the
random access files on the disk, and the count and
accumulative space used by the sequential files and the
random access files, respectively.
2. /R - The /R option causes PAKIT to operate only on the
random access files. It will skip the process of
checking the sequential files for position. Directory
blocks will be read, but not moved.
3. /S - The /S switch will cause PAKIT to operate only on
the sequential files. It will skip the processing and
moving of the random access files. Directory blocks will
be read, but not moved.
(continued)
Page 4
PAKIT
Optional Modes of Operation
(continued)
4. /Q - The /Q switch is the most interesting and useful of
the switches. It provides a means of doing an "almost"
pack, in a quicker fashion. Since the location of the
first block in all sequential files is contained in the
directory, you don't need to read a block in order to
make a decision on the first block. If we make the
assumption, often valid, that the rest of the sequential
file will be somewhere nearby, then if the first block
does not need to be moved, then very likely neither does
the rest of the file (and vice-versa). With the /Q
switch on, PAKIT will make a decision based on this
assumption and scan the rest of each sequential file only
if the assumption justifies it. Additionally, for this
decision the high-water mark is moved down to 75% of the
normal mode's value. This way some files that are close
enough to the boundary will be scanned anyway.
5. [p,pn] - Including a P,Pn specification with your disk
specification will cause PAKIT to begin its processing at
that P,Pn, skipping the scanning and relocating of any
files in P,Pn's below that number. This causes faster
but still effective processing because, as experience has
shown, most of the editing and erasing of files occurs in
a few, higher P,Pn areas. Therefore most of the
advantage of relocating files can be found in the files
contained in those P,Pn areas.
As you use PAKIT more often, the disk that is being packed
tends to become "acclimated" to PAKIT. The more frequently you
use it, the quicker and more effective will be the /Q mode. This
is because your less frequently modified files tend to float to
the bottom, and the fewer files that you access frequently will
float around on top. It's a process of sedimentation.
Use the FREE program included with PAKIT to determine the
effectiveness of PAKIT operations in their various modes. You
should not need to use PAKIT more than once a day, even in the
most active environments.
Page 5
PAKIT
Bells and Whistles
As PAKIT does its work, it will type on the screen certain
information about what it is doing. This includes:
1. ' - a quote mark is typed each time PAKIT moves a
directory or MFD block.
2. file name - the file name of a sequential file is type as
PAKIT scans its structure to determine if blocks within
it should be moved.
3. <- - an arrow is typed beside the name of a sequential
file when at least one block in that file is being moved.
4. random access file directory - PAKIT lists a directory of
all the random access files on the disk before it goes
onto process them.
5. file name - again, PAKIT types the name of a file, this
time a random access file, as it processes it.
6. ^ and v - to move a random access file, PAKIT reads as
many blocks of that file as possible into memory, then
writes those blocks back to their new location. This
method minimizes the amount of head movement in the disk
drive itself. Each time a random access block is read,
PAKIT types a v; each time a block is written back, PAKIT
types a ^.
Page 6
PAKIT
! ! ! ! CAUTION ! ! ! !
It is important that no other jobs be accessing the disk
that is being packed. In fact, no other program should have files
open on that disk. Since the process of PAKIT is to move files
around on the disk, those files will not be where other jobs
expect them once PAKIT is finished; the other jobs must look up
their files again. So all programs accessing the disk that is
being packed must be restarted after PAKIT is finished.
One notable example is the DRAVAC software, ANDI and
TSASS. These programs keep pointers to files on the disk in their
local memory. This is one of the reasons that they can access
files and databases so quickly. PAKIT may move one of the files
that they are pointing to; then they'll be looking in the wrong
place for it. The interesting point about this example is that
TSASS is a program that is running all the time! If PAKIT finds it
necessary to move a TSASS file, then you will have to reset your
system in order to continue properly.
So the rule is,
1. Before you run PAKIT, exit all programs that are
accessing files on the disk you are going to pack.
2. If you are running TSASS, then do PAKIT on all disks you
wish to pack, then reset the system.
You should be careful when using PAKIT. This program is
operating on the very structure of your disk and files, so an
abnormal interrupt of the program can be dangerous. (An
interruption by control-C is perfectly safe). If the system fails
while PAKIT is running, some file or some directory may be lost.
If the system fails while PAKIT is moving a random access file,
that file will have bad data in it. If the failure is while PAKIT
is processing a sequential file, then the structure of that file
may be damaged. If the failure is during the first few moments of
PAKIT, while it is operating on the directory blocks, then whole
directories may be lost. A DSKANA m_u_s_t_ be executed if the
system fails in the middle of a PAKIT operation.
