Is size on disk 512 or 4096 bytes

[hubbobubbo]

Hi

I use a small routine that calculates CRC on files. This routine reads
in 4096 bytes at a time, I assume this is set as the smallest file size
(size on disk) available. This seems to be valid when I check a small
file in my Windows XP installation. However when I check my Windows
2000 installation the size on disk for a small file is only 512 bytes.

Both systems are installed with NTFS.

Can someone explain how this works, is 512 the smallest size on disk on
2000? Can there be other combinations for instance if you use FAT
instead of NTFS etc.

All comments appriciated.

 

[Jerold Schulman]

Hi

I use a small routine that calculates CRC on files. This routine reads
in 4096 bytes at a time, I assume this is set as the smallest file size
(size on disk) available. This seems to be valid when I check a small
file in my Windows XP installation. However when I check my Windows
2000 installation the size on disk for a small file is only 512 bytes.

Both systems are installed with NTFS.

Can someone explain how this works, is 512 the smallest size on disk on
2000? Can there be other combinations for instance if you use FAT
instead of NTFS etc.

All comments appriciated.

If you converted your W2K file system to NTFS, as apposed to installing it, the allocation unit is 512 instead of 4064.
The W2K convert.exe uses 512 byte Allocation Units.

See tip 0862 » Windows NT default allocation unit.
in the 'Tips & Tricks' at http://www.jsifaq.com
for the default allocation unit size when you format a partition.




Jerold Schulman
Windows Server MVP
JSI, Inc.
http://www.jsiinc.com
http://www.jsifaq.com