Frequently Asked Questions


How can I determine which installer to download?

  1. open the Run dialog by hitting [Windows]+R
  2. type cmd.exe /K echo %PROCESSOR_ARCHITECTURE%
  3. hit the OK button
  4. examine the top-left corner of the opened command prompt window
    • If it reads x86 you download the i386 installer.
    • If it reads AMD64 you download the amd64 installer.
    • If it reads IA64 you download the ia64 installer.

Can I up- or downgrade over an existing installation?

The installer is written to support up- and downgrading without the need to remove a previous version. In addition, usually it is not needed to reboot.

Can I specify a custom installation folder?

Starting with version 5.1.0 it is supported to specify the install location. The installer validates the selected location, since only empty and existing UltraDefrag installation folders are supported.

How can I check what went wrong with my silent installation?

Starting with version 5.1.0 a log file is created at %TMP%\UltraDefrag_Install.log.

General Usage

After defragmentation I see my restore points disappeared, what happens?

This is a normal situation when restore points disappear after an intensive disk processing. Windows limits amount of disk space reserved for restore points. When you perform intensive disk processing, Windows tracks changes through system restore, therefore the mentioned limit may be easily exceeded which results in old restore points deletion.

We would recommend to avoid the use of restore points for serious purposes, because Windows can never guarantee that some point saved in the past will be available in the next moment. Use backup software instead, Windows already has such a program and there are also lots of 3-rd party programs of such kind.

How can I determine the fragmentation percentage of a drive?

Starting with version 5.1.0 the analysis calculates the fragmentation percentage.
It is displayed in the Fragmentation column of the drive list of the GUI and when you run the command line tool using the -v command line parameter.
You can run an analysis of a drive from the Explorer context menu too.

How can I optimize similar to v5.x.x in v6.x.x?

Starting with version 6.0.0 the optimization no longer ignores filters. In addition there is a new filter added that skips files of a specified size when running optimization.
To get a similar behavior of v5 in v6, you need to disable/unset all filters and set the variable UD_OPTIMIZER_FILE_SIZE_THRESHOLD for the boot time and console interfaces respectively the setting optimizer_file_size_threshold for the GUI to 15 EB.

Graphical Interface

Where can I find a legend of the cluster map colors?

The colors are described in the Cluster Map section of the Graphical Interface page.

When will the cluster map become interactive, so I'll be able to know where individual files are located on disk?

When defragmentation algorithms are quite effective, this is not necessary to know location of individual files - anyway you'll get your drive optimized quite well. Maybe we'll implement the discussed feature later, but now we prefer to concentrate our forces on a disk optimization algorithm improvements.

Why configuration files editing is better than one settings window with tabs?

It is much easier and reliable to use the standard Notepad application to edit configuration files.

Why does the progress percentage update irregularly?

The progress percentage measures disk space, not the number of files. So when few big files are analyzed, the progress will increase very fast. Conversely, when thousands of small files are analyzed, progress will be relatively slow.

Why is the progress exceeding 100%, when processing FAT disks?

On FAT disks space is immediately released after a file is moved, so it happens, that more files can be fully defragmented, than initially calculated.

Why is the disk name not displayed?

Explorer replaces an empty disk name by Local Disk or similar, UltraDefrag does not replace an empty disk name with any default.

Why is only the last report displayed, if I choose to display multiple reports?

Browsers which do not support tabbed browsing are reusing the same window. This is a limitation of the way a HTML page is opened from within Explorer.

Why are multiple windows opened, if I choose to display multiple reports?

If your browser supports tabbed browsing open one instance of your default browser before you display the reports. This will open each report in a new tab depending on your browsers configuration.

Command Line Tool

How can I process all disks except a few?

You can use the filter variables to do this. For instance you like to defragment all fixed drives except C and S.
To achieve this you use set UD_EX_FILTER=C:\*;S:\* and execute udefrag --all-fixed.
The analysis will be executed for any drive, but defragmentation will be skipped for drive C and S.
The analysis will not be complete for excluded FAT disks, because the driver does only check the root folder of excluded disks.

Boot time processing

What is the best configuration for boot disks?

For NTFS it should be sufficient to use quick optimization. For FAT it is highly recommended to convert the boot disk into NTFS due to performance and security reasons.

Why are there still some files fragmented?

Some system configurations are locking files even at boot, which can't be prevented. In some cases the size of the free space regions is not big enough to hold the entire file, this can be corrected by using quick optimization, which consolidates free space.


How can I disable the boot time defragmenter manually?

If something goes wrong and the boot-off script does not work properly, remove the defrag_native entry from the following system registry parameter manually:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\BootExecute

I have set UD_LOG_FILE_PATH or log_file_path, but the log file is not created?

If creating the log file fails for any reason, UltraDefrag tries to create the log file in the temporary folder of the current user.
Only if creating the log file in the temporary fails too, there will be no log file created.
The default temporary location for the GUI and console edition is: %TMP%\UltraDefrag_Logs\{filename}
The default temporary location for boot time defrag is: %SystemRoot%\UltraDefrag_Logs\{filename}
The file name is the one from the specified log file path variable.

How many differences are between the Ultra Defragmenter and well known MyDefrag (previously JkDefrag)?

Both programs have similar disk analysis algorithms, but defragmentation is done in different ways. While MyDefrag tends to give more control over a files placement, UltraDefrag is designed to be as simple and fast as possible. So, UltraDefrag never uses a complex disk optimization strategies, because their use often noticeably increases the processing time.

The biggest advantages of UltraDefrag are an ability to defragment system files at boot time, nice graphical interface, handy reports and instant availability of sources licensed under GPL.

The main disadvantage of both applications (UltraDefrag and MyDefrag) is that they are based on the Windows defragmenting interface that has a very ugly implementation. We cannot change this, because it is part of the filesystem drivers (ntfs.sys, fastfat.sys), which are too complex and not open source to modify or replace them.

Previous: Tips and Tricks Next: Reporting Bugs