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If you convert your partitions to NTFS you may wind up with an unoptimal cluster size of 512 bytes instead of the default 4K size for newly formatted NTFS partitions.

You can get an NTFS drive with a 512 byte cluster size to have a 4K cluster size using the cluster changing functionality in Paragon Partition Manager (uses its own FAT to NTFS converter) or the now discontinued Norton Partition Magic 8.0. (uses convert.exe for all NTFS conversions).

If you have Partition Magic 7.0 or 7.01 which only allows for the changing of cluster sizes on FAT16 or FAT32 partitions and which launches convert.exe for all NTFS conversions you can follow these steps which require Windows XP (Home or Professional).

  1. Turn off system restore for the partition to be altered (It will turned back on later.).
  2. Issue compact /u /a /s /i from a command prompt to uncompresses all files.
  3. Remove any sparse data.
  4. Make note of any NTFS permissions beyond your O.S. defaults.
  5. Use P.M. to convert the partition to the FAT32 file system (requires no compressed or sparse data be present on the partition).
  6. Use P.M. to change the cluster size of the partition from 512 bytes to 4K.
  7. Use P.M. to convert the partition to FAT32 (4K aligned).
  8. Use P.M. or covert.exe to convert the partition to NTFS.
  9. Turn system restore back on.
  10. Reinstate the NTFS permissions you noted in step 4.

System restore has to be turned off as it compresses system data that cannot be uncompressed by the compact program.  You will need to apply the changes for the partition alterations in steps 5-6 and reboot as prompted before the P.M. convert dialog box will show the FAT32 (4K aligned) choice referenced in step 7.

After the final conversion you can check the cluster size by running chkdsk in the read only mode (look for bytes in each allocation unit), performing a defragmentation analysis with the XP defragmenter (look at the report), or using the info command in P.M.

Following are the actions that will result in an NTFS partition having a 512 byte cluster size.

  • Using the NTFS file system option when formatting a partition during an NT4 setup.  The NT4 WS, NT4 Server, and NT4 Enterprise Server setups format all partitions as FAT16 and convert them to NTFS later if you opted for the NTFS file system.

    This is why your boot partition is limited to 4 gigabytes (achieved through FAT16 with 64K clusters) even though the maximum allowed is the capacity of the drive's 1st 1024 cylinders (usually 7.8 gigabytes).
  • Running convert.exe for a FAT16 or FAT32 partition on an NT4, a W2K system, or in some cases an XP system.
  • Formatting a partition as FAT32 during a W2K and in some cases an XP setup and running convert.exe for it after the setup.

In Windows XP convert.exe will maintain a partition's existing cluster size if the partition is aligned so that the number of sectors in the system area is a multiple of eight.  If this is not the case a 512 byte cluster size will be used as with the NT4 and W2K convert.exe.

For more information see: