Actually..... >I'd like the proper answer to that as well. I guessed that unformatted >capacity represents the total amount of data that can be stored on the disk. > Formatting added extra information (like an [un]allocated sector/cluster >map, root directory, boot info and program, etc) that needs to be stored >somewhere and so comes out of that "unformatted" capacity.
It's worse than that Jim. Basically, the "unformatted capacity" is the total amount of sectors on the disk, including those used by the disk drive itself to store the defect list and, on newer disks, a pool of sectors which can be mapped in to replace defective sectors. There's also usually a couple of sectors used for the drive's configuration settings. Quite often, for ease of use, basically two cylinders are reserved by the firmware for all this. You should also remember that the metric for K, M and G used by hard disk manufacturers is based on powers of 10, i.e. 1000, 1000000 and 1000000000 and multiples of 1024. Now, that's the amount of user available space. Now you have to add the overhead for the boot sector, partition table before even thinking about the data space used by the filesystem. The filesystem's overhead differs with the type but it can be quite large, especially if there are huge numbers of small files. Now, we've not finished yet. Although the raw disk works in sectors the filesystem works in blocks, which may or may not be the same size as a sector. Most filesystems have blocksizes starting at 4K, which is either 8 sectors or 4 sectors on the newer large capacity disks. Some filesystems, such as FAT32, will increase the block size (MS calls it the cluster size) up to 32KB. The problem with this is that the minimum amount of disk space able to be allocated is 1 block, which means that if you have 1024 1 byte long files they will take up a massive 32 megabytes (plus space in the FAT) on a large FAT32 partition instead of the 1KB you thought it would. I hope that gives you some idea about this thorny issue and helps you discover where all that disk space you thought you had has gone to. Steve -- --------------------------------------------------------------------------- Nostalgia isn't as good as it used to be. _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
