1. Windows Machine
If you use ntfs file system you can use fsutil fsinfo ntfsinfo drivename: to get information of block size.
c:>fsutil fsinfo ntfsinfo f: Microsoft Windows XP [Version 5.1.2600] (C) Copyright 1985-2001 Microsoft Corp. C:Documents and SettingsAdministrator>fsutil fsinfo ntfsinfo D: NTFS Volume Serial Number : 0xc054aec854aec090 Version : 3.1 Number Sectors : 0x000000000c34f28c Total Clusters : 0x0000000001869e51 Free Clusters : 0x00000000015f0419 Total Reserved : 0x0000000000000000 Bytes Per Sector : 512 Bytes Per Cluster : 4096 Bytes Per FileRecord Segment : 1024 Clusters Per FileRecord Segment : 0 Mft Valid Data Length : 0x0000000003528000 Mft Start Lcn : 0x00000000000c0000 Mft2 Start Lcn : 0x0000000000c34f28 Mft Zone Start : 0x00000000000c3520 Mft Zone End : 0x00000000003cd3e0 C:Documents and SettingsAdministrator>