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1. What is FAT16, what is a cluster?
2. Why use my data more space on disk than their size is?
3. Why should I partition my disk?
4. The data of my 450 MB hard disk do not fit on my new 600 MB hard disk!
5. What is FAT32?
6. How can I create a FAT32 partition?
7. Can HD95COPY backup a FAT32 drive?
8. How can I backup a disk containing both FAT16 and FAT32?
9. I want to backup to a Windows 95 network. How can I generate a boot disk and connect to the server?
10. How can I change the drive for the backup file?
11. Can I backup directly to tape or restore from there?
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A file is stored on disk in pieces, so called clusters.
The FAT (file allocation table) is a chain of pointers: The directory entry points to the first cluster (e.g. 27). The corresponding FAT entry (27) contains the number of the next cluster and so on. The last cluster of the file is marked by EOF.
The lowest cluster number is 2. In FAT16 each cluster number is stored as a word (16 bit), so the highest possible cluster number is 65535.
Therefore the highest possible capacity of the drive depends on the cluster size:
127 MB if cluster size is 2 KB
255 MB if cluster size is 4 KB
511 MB if cluster size is 8 KB
1023 MB if cluster size is 16 KB
2 GB if cluster size is 32 KB
You set the cluster size when you partition your hard disk using FDISK. But be careful: deleting a partition means loss of all data!
(There is a little bug in FDISK: if you are asked for the partition size enter a little less than you want - e.g. 1019 instead of 1023)
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Each little file and each directory occupies a whole cluster. And in the average half of a cluster is lost for each file (let's assume a cluster size of 4096 byte and a file size of 13000 byte. this file needs 4 clusters, and 3384 bytes in the last cluster are unused.)
E.g. my C: drive (FAT16) looks like this (use CHKDSK to see it):
1.069.039.616 Bytes disk size
10.321.920 Bytes in 117 hidden files
12.468.224 Bytes in 749 directories
1.003.765.760 Bytes in 16.310 files
42.434.560 Bytes available
16.384 Bytes per cluster
65.249 clusters
2.590 clusters available
So 62.659 used clusters are 1.026.605.056 used bytes, but my data are only about 840.000.000 bytes.
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A partition of - say - 1,4 GB uses a cluster size of 32 KB.
If you divide it into two parts of 1 GB and 400 MB, the cluster sizes are 16 KB and 8 KB. Therefore the unused but occupied space is much less!
If your hard disk has 1048 MB it is much better to set the partition size to 1023 MB and to forget the other 25 MB!
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This could happen because the cluster size has changed from 8 KB to 16 KB.
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FAT32 was introduced with Windows 95 OSR2.
The cluster number is stored in a double word, so there are more cluster numbers available and there is no need to increase the cluster size: Until 4 GB the cluster size is always 4 KB.
Advantages:
You loose less space because the cluster size is only 4 KB
The drive size can be more than 2 GB as for FAT16
Disadvantages:
FAT32 could be slower as FAT16 (overhead because of more clusters per file)
Only Windows 95 OSR2 (and its DOS 7.1) can "see" a FAT32 drive.
(DOS 3.x - DOS 6.x and previous versions of Windows 95 have no access)
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First of all you have to use Windows 95b (OSR2)
When you partition your hard disk with FDISK it will ask you whether to support FAT32 or not. If you choose "yes" all drives bigger than 512 MB will be FAT32, all drives less than 512 MB will be FAT16.
This is the default of FDISK. But if you use the (undocumented!) parameter /FPRMT (don't ask me what it means!) FDISK will ask you whether the default should be changed.
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HD95COPY does not support FAT32. If you start the program you get the message "You can use this program only for FAT16". Use FAT32CP instead.
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If you start the program drive C: is checked for the correct file system. (You can use HD95COPY only for FAT16, FAT32CP only for FAT32).
If your hard drive contains partitions of type FAT16 and FAT32 you can define the "correct" drive by command line parameter /D:.
Example: C: is FAT32, D: and E: are FAT16. You want to back up drive E:. You use HD95COPY with command line parameter /D=E.
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That's what you do to boot from a floppy disk and connect to your Windows 95 network:
Install Windows 95 with network support (without any applications to keep the registry small - it should fit on your floppy disk!). Take a formatted disk and make it bootable by "SYS A:"
Copy the following files from your windows directory to the disk:
(first make system.dat visible by
attrib -r -s -h c:\windows\system.dat)
himem.sys
net.exe
net.msg
neth.msg
ndishlp.sys
protman.dos
protman.exe
xxxxx.dos (your network card, e.g. elnk3.dos or ne2000.dos)
*.pwl
system.dat
protocol.ini
system.ini (search for [password lists] and change the path to a:\)
CONFIG.SYS
device=a:\himem.sys
device=a:\protman.dos /I:a:\
device=a:\ndishlp.sys
device=a:\xxxxx.dos (e.g. elnk3.dos)
AUTOEXEC.BAT
net start workstation
net use [drive] [resource]
(e.g. net use e: \\PC01\BACKUP, if BACKUP on your server PC01 contains the backup file.)
Now you can boot any PC using this floppy disk and restore from the network!
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If you select a backup file the default drive is shown. You can change it by typing the drive (e.g. "E:") and "Enter"
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If your tape drive is supported by the freeware DATMAN (at http://www.datman.com) you can assign a drive letter to your tape drive and use it like a hard disk. It means HD95COPY can directly store the backup file there or restore from there!