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Windows XP > Windows XP, Installing and Setup > NTFS

Optimize NTFS Performance

By: Arie Slob

Users can determine many of the factors that affect an NTFS volume's performance: choosing important elements such as an NTFS volume's type (SCSI, IDE), speed (RPM of the disk), and the number of disks the volume contains. In addition to these components, the following factors also influence an NTFS volume's performance:

  • The cluster and allocation unit size
  • If the NTFS volume was created from scratch or converted from an existing FAT volume
  • If the volume uses NTFS compression
  • The location and fragmentation level of frequently accessed files, such as the Master File Table (MFT), directories, special files containing NTFS metadata, the paging file, and commonly used user data files
  • Whether you disable unnecessary NTFS behaviors

Cluster Size

Choose a volume's cluster size based on the average type and size of file that the volume will store. Ideally, the volume cluster size should be evenly divisible by the average file size (rounded to the nearest KB). An ideal cluster size minimizes disk I/O overhead and wasted disk space. You should note, however, that using cluster sizes greater than 4KB has several potentially negative side effects:

  • Disk-defragmentation utilities can't defragment the volume
  • NTFS file compression can't be used
  • The amount of wasted disk space increases

There are several options to determine the average file size. One option is to run CHKDSK on the volume (Start > Run type cmd in the Open box, press OK. In the command window type chkdsk, press [Enter]), then divide the total kilobyte disk usage by the number of files on the volume. Another option is to use Performance Monitor (Start > Control Panel > Administrative Tools > Performance) to track the LogicalDisk object's Average Disk Bytes/Transfer counters for the disk in question. This method provides you with a more accurate idea of the average file size as well as the type of data stored on that disk.

In general however, the 4KB default NTFS cluster size used on volumes from 2GB to 2TB will be fine.

Converting from FAT

Volumes that are converted from FAT to NTFS will lack some performance benefits. Fragmentation of the MFT (Master File Table) might occur.

To check the level of fragmentation of the MFT, select Start > All Programs > Accessories > System Tools > Disk Defragmenter. Run an Analyses of the drive, then press View Report. Scroll down to the entry for Master File Table (MFT) fragmentation.

Master File Table fragmentation

The format command in Windows XP Professional now aligns FAT data clusters at the cluster size boundary. This alignment improves the conversion of FAT volumes to NTFS because the convert command can now use a variable cluster size, up to a maximum of 4KB, for converted volumes, instead of a fixed 512-byte cluster size as used in Windows 2000.

The problem is that if the FAT volume was formatted using an operating system other than Windows XP, the cluster size of the converted volume is usually 512 bytes. However, if the FAT clusters happen to be aligned at the cluster size boundary, Windows XP Professional can use the variable cluster size for the converted volume. There has been much discussion on Windows XP forums & newsgroups about which conditions should be met to have "aligned" clusters on a non Windows XP formatted FAT disk. I have personally used the format command of Windows 98 Second Edition Edition to format hard disks on a number of occasions, and when I choose to convert to NTFS during the subsequent Windows XP installation, this resulted in a cluster size of 512 bytes.

512-bytesw clusters after FAT32 > NTFS conversion

When 512 bytes clusters are used, this increases the likelihood of fragmentation, and will cause the Disk Defragmenter to take a significant amount of time to defragment. So, all in all, you are better off formatting a drive as an NTFS drive in the first place. Most people will complain of slow performance, only to find out that their NTFS is running with 512 bytes clusters!

If you have already converted your file system to NTFS, and you notice that you are running with 512 byte clusters, you have to reformat. If you have lots of data and/or installed progrems, make a full system backup. You'll need a 2nd hard drive, or use another (networked) PC's storage. Then reinstall Windows XP (boot from the XP-CD - more info here), and restore the backup (you should make a full system backup anyway before doing the conversion. There's always a minimal chance of corruption or data loss. Don't say I didn't warn you!).

Note: If you upgraded from a previous Windows version to Windows XP, converting to NTFS will mean that you cannot uninstall Windows XP (if you choose to save your previous system files during the upgrade).

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