Volume Difference for Same File While Copying

Check the file system on the hard drives. If one is formatted FAT16 or FAT 32 or NTFS and the other one not it could show different files size for same file.

The reason is that the files might need more space on the disk due to cluster size and/or due to level of fragmentation. The system should give you two values for your files:

1. Size of file

2. Size on disk

Check the properties. Number one should be the same but the second one could differ. This is particularly obvious in larger file sizes.

Hope this explains it!

Hard drives when formatted have set sector sizes, and software also sets minimum cluster sizes, based on rotational latency of the drive, buffer memory size of the drive, and data pathway speeds in the interface. Different sizes of drive then, will have different basic sector sizes. In the basic format, write of a file to a sector will fill the sector and any leftover data space in the sector is not released to the OS for available storage. You will see this on small text files where for example the OS will report that the files size is 886.75K and the size on disk is 1000k. this is a 886750 byte file stored on a sector of 1.0Mb. In this case, a file just over 1.0Mb in size will then use 2 sectors, and the second sector will be largely unoccupied by useful data. Clusters of sectors are there to allow really large files to be written in an unfragmented fashion, but the clusters are not set in stone and the unused sectors in the cluster can be released to the OS for other storage. In the same way, files which left large amounts of unused space in a smaller drive will now fit into the larger sector size of the big drive more efficiently, giving a different volume report fot the file and disc space used.

When compression occurs, compression software can use the leftover space in the sector to store the beginning of a second file, and so on, to make the most efficient use of space, however overhead is required to keep track of the exact starting point of the appended file space and where the rest of the file is stored as well. Other compression techniques involve using algorithms to identify patterns in the data; files compressed in this way are usually dedicated to the software and algorithm that compressed it and may not be recoverable by another compression software. ( MP3-64, MP3-128, MPEG, JPG, JPEG, etc. )

You will also see messages from time to time when transferring files from HD to CD/DVD or SD memory that tell you there is additional data at the end of the file that will be lost; this is the unused sector space on the HD which often contains repeated segments of the file, or original formatting pattterns, or other file portions, due to defragmentation reorganizing files into contiguous sectors.

Hope this helps,

L I T.