home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Shareware Overload Trio 2
/
Shareware Overload Trio Volume 2 (Chestnut CD-ROM).ISO
/
dir34
/
dos999.zip
/
31603.TXT
< prev
next >
Wrap
Text File
|
1993-06-30
|
7KB
|
182 lines
_______________________________________________________________
STACKER NOTE STACKER NOTE
Title: STACKER DRIVE SPACE REPORTING
(Applies to Stacker for Windows & DOS 2.x & 3.x)
STAC FAX 31603 (6/93)
_______________________________________________________________
BACKGROUND
Stacker 2.0's SCHECK or Stacker 3.0 & 3.1's CHECK /D show
exactly how the space has been used in the Stacker drive.
Here is an example of an SCHECK & CHECK /D report:
Volume in drive C is STACVOL_DSK
No errors found
Stacker Drive Statistics:
Stacker Drive STACVOL File
Drive C: D:\STACVOL.DSK
------------------ -----------------
Total Bytes: 147,095,552 73,550,336
Bytes Used: 60,334,080 (41.0%) 33,004,032 (44.9%)
Bytes Free: 86,761,472 (59.0%) 40,546,304 (55.1%)
Bytes per Cluster 8,192 2,048
Stacker Drive Compression Ratio = 1.8:1
Projected Bytes Free = 74,096,640
Fragmentation Level = 0%
Note:
Not all the lines will be displayed if
Stacker version 2.x SCHECK utility is used.
What does it all mean?
The Left Column: This column contains information about your
"logical" drive's data. The figures are "based on an
anticipated compression ratio of 2.0:1." In this example,
your compressed drive (Total Bytes) has been established at
approximately 147 MB. There are approximately 60 MB used
with enough clusters left on the compressed drive to
accommodate approximately 86 MB of additional data. Utility
programs which have the capability of reporting available
disk space could report either "Bytes Free" or "Projected
Bytes Free."
_______________________________________________________________
Copyright 1993, Stac Electronics Page 1 of 3
The Right Column: This column shows the usage of actual
"physical" hard disk space inside the STACVOL.DSK file. The
Stacvol file contains all of the data and free space for the
Stacker drive C. Its name and location are shown in the
column header. In our example, D:\STACVOL.DSK is about 73 MB
in size and has used only 33,004,032 bytes of storage space.
Therefore, there are 40,546,304 bytes of physical free space
left in D:\STACVOL.DSK.
Compression ratio
The Stacker drive compression ratio indicates the average
compression of all the files in that drive. The
compressibility of the files is generally dependent on their
contents. In the above example, the 1.8:1 ratio is slightly
less than a 2.0:1 ratio you typically get for an average
mixture of files. This tells us that the files in this
Stacker drive are taking up slightly more space than if the
compression rtio was 2.0:1.
A drive full of graphics files may achieve an average
compression of 8.0:1 or more. An 8.0:1 ratio would mean that
the files are taking up 1/8 the space they would on a
standard drive.
Conversely, some files are already compressed, such as
"zipped" files. Stacker will attempt to compress these files
even more however, since these files have already been
previously compressed, little or no additional compression
occurs. Previously compressed files will actually lower the
average compression ratio for the compressed drive in which
they reside. If you used a third party utility to "zip" the
files, you could improve your average compression ratio by
either storing these files on an uncompressed drive/diskette
or by "unzipping" the files and let Stacker compress them.
Note
The drive compression ratio does not display
if the drive is empty.
Projected bytes free
This number is Stacker's "estimate" of the available space
left on the Stacker drive. It is determined by one of the
following methods:
Method 1. By multiplying the physical bytes free (right
side) by the compression ratio if it is less
than 2.0:1. The example shows the compression
ratio rounded off to tenths. The actual
compression ratio used in the calculation is
not rounded off.
-------------------------------------------------------------
Copyright 1993, Stac Electronics Page 2 of 3
Method 2. The logical bytes free (left side) if your
compression ratio is 2.0:1 or greater.
The projected bytes free is limited to the smaller of these
values.
In our example, physical bytes free multiplied by the
compression ratio would be 74,096,640. However, there are
enough unallocated clusters to accommodate the 86,761,472
bytes free from the left side column (based on an anticipated
compression ratio of 2.0:1). The Projected Bytes Free become
the smaller of these two values.
Note
When the number for physical bytes free goes
to zero, the drive is full. You cannot "grow"
the drive to create more physical space.
Also, if the drive is less than 12% full, the
projected bytes free will equal the "logical"
bytes free number (left column).
Expected Compression Ratio
If your average compression ratio significantly varies from
your original compression ratio (default is 2.0:1 unless
modified) established when you installed Stacker, you can
either increase the number of allocation units or decrease
them. You would do this by either adjusting the "Expected
Compression Ratio" from the Stacker Toolbox in version 3.x
or by using "Grow & Shrink" from the Stac Command Assistant
in version 2.x of Stacker. You can only adjust the expected
compression ratio within a range that is either twice or half
the original value established at installation time (normally
2.0:1 unless you originally set it at another value). By
adjusting the Expected Compression Ratio (GROW operation in
version 2.x) you can adjust the figures being reported in the
left column to improve the accuracy of available space.
Since your average compression ratio can fluctuate as you
add, modify or delete files from your drive, modifying the
expected compression ratio should only be done if there is a
"significant deviation" from the original compression ratio
(normally 2.0:1) established when you installed Stacker.
_______________________________________________________________
Copyright 1993, Stac Electronics Page 3 of 3