HARDY%USC-ISI@sri-unix.UUCP (05/11/84)
I have been using "WINDRIVE" by Tall Tree Systems to split up my hard disk drive into drives C thru K. The documatation talks about upto 50MB. I currently use it to get around using sub-directories. Howerver, you may want to use it to change the cluster size. Depending on the size of each drive, the cluster size changes from 512 to 16k bytes. Rich Hardy.\
broehl@wateng.UUCP (Bernie Roehl) (05/15/84)
Yes and no; simply patching bytes in the BPB will change how the disk
looks to the OS (assuming the driver is well-written and pays attention
to the BPB instead of blithely assuming particular values). However,
make sure that you change *all* the neccessary values in the BPB; changing
only some of them will drive dos nuts.
Needless to say, you should only do such things to a freshly-formatted
volume, less you corrupt what's already out there.
So much for the "yes" part. The reason there's a trade-off between volume
size and cluster size is because you have finite-sized FAT's. Yes, you
can increase the FAT size (i.e. the number of FAT's), but you have to be
*damn* sure that DOS is clever enough to use such big FATS's.
I haven't enough information on the internal workings of DOS to say for
sure if it does or not; perhaps some of the folks at Microsoft would care
to elaborate on all of this for the net?
--
-Bernie Roehl (University of Waterloo)johna@haddock.UUCP (05/17/84)
#R:sri-arpa:-60000:haddock:13600007:000:866 haddock!johna May 16 16:09:00 1984 > So much for the "yes" part. The reason there's a trade-off between volume > size and cluster size is because you have finite-sized FAT's. Yes, you > can increase the FAT size (i.e. the number of FAT's), but you have to be > *damn* sure that DOS is clever enough to use such big FATS's. This information is not correct! The reason for the trade-off is because each FAT entry is only 12 bits. Expanding the number of FATs will do nothing. Only one FAT is normally used, the other is there for recovery procedures. FAT = File Allocation Table Clusters (allocation units) are linked together using the FAT. Reducing the sectors per cluster will just hide part of your drive from DOS. DOS for the PC contains a table on the first real sector of the fixed drive which is used to partition a fixed drive. It is documented in DOS 2.0 . ima!haddock!johna