IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning

Chapter 9. Open system servers - Windows 327

names, bad-cluster remapping, multiple data streams, general indexing of file attributes, and

POSIX. All of these contribute to making NTFS a robust file system.

Windows 2003 uses the following default cluster sizes for NTFS, as shown in Table 9-3,

where the value for number of sectors assumes a standard, 512 byte sector. On systems with

sectors that are not 512 bytes, the number of sectors per cluster may change, but the cluster

size remains fixed.

Table 9-3 NTFS default cluster sizes

These values are only used if an allocation unit size is not specified at format time, using the

/A:<size> switch with the format command.

9.3.2 Disabling short file name generation

By default, for every long file name created in Windows, NTFS generates a corresponding

short file name in the older 8.3 DOS file name convention for compatibility with older

operating systems. In many instances this functionality can be disabled, offering a

performance increase.

If you use large numbers of files in an NTFS folder (300,000 or more), disable short-file name

generation for better performance, and especially if the first six characters of the long file

names are similar.

Before disabling short name generation, make sure that there is no DOS or 16-bit application

running on the server that requires 8.3 file names, nor are there any users accessing the files

on the server via 16-bit applications.

To disable the generation of 8.3 short names, edit the following registry parameter:

HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Control \FileSystem

\NtfsDisable8dot3NameCreation

Change its value from 0 to 1. In Windows Server 2003, this parameter can also be set by

using the command:

fsutil behavior set disable8dot3 1

9.3.3 Disable NTFS last access updates

Each file and folder on an NTFS volume contains an attribute called Last Access Time. This

attribute shows when the file or folder was last accessed, such as when a user performs a

folder listing, adds files to a folder, reads a file, or makes changes to a file. Maintaining this

information creates a performance overhead for the file system especially in environments

Drive size Cluster size Number of sectors

512 MB or less 512 bytes 1

513 MB to 1024 MB (1 GB) 1 K 2

1025 MB to 2048 MB (2 GB) 2 K 4

2049 MB to 2048 GB (2 TB) 4 K 8

Note: The maximum NTFS volume size as implemented in Windows Server 2003 is 2

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clusters minus 1 cluster. For example, using 64-KB clusters, the maximum NTFS volume

size is 256 terabytes minus 64 KB. Using the default cluster size of 4 KB, the maximum

NTFS volume size is 16 terabytes minus 4 KB.