Frequently Asked Questions (FAQ)
 | Which systems are supported? |
All Windows 32 Bit and 64 Bit versions beginning with Windows 2000 up to Windows 7 are supported.
| How many files can be calculated during a single search? |
Dupehunter Professional can calculate more than 7 million files in a single search. The only limitation is the maximum size of 2GB RAM for the Dupehunter process.
| Are the Dupehunter executables digital signed? |
Yes! Beginning with version 6.5.0.3080 the Dupehunter.exe and also the whole setup file called DHPro.exe are digital signed by Globalsign!
If you download a setup from third party sites, pay attention to this certificate. Especially under Vista and the User Access Control (UAC) the user gets a message from the system in a light blue message box, not yellow or red! Also, for the Setup file the description is named as "Dupehunter Professional Installation" by "Carsten Heidtke". Alternatively, you can call the properties of the Setup file by using the right mouse click on the file. On the tab "Digital Signature" you should find our signature. If not, do not hesitate to contact us about where the Setup comes from (Download Site).
| Can I save the results of the search? |
Yes, you can export the results to the formats XML and CSV. Both formats supports Unicode UTF-16 encoding.
We recommend using the XML export format, which offers high speed and supports extremely large lists .
| Interaction with Antivirus programs |
Antivirus programs like Norton AntiVirus or others run in the background to check file operations.
It is a good idea to stop the antivirus checker during a search with Dupehunter Professional. If this is not possible for security reasons, change the settings so that the checker is only activated on "writing files".
This will increase the performance considerably! Tested with one million files and activated antivirus program like Norton Antivirus or H+B EDV AntiVir, Dupehunter Professional takes more than 27 minutes for execution. After changing the settings of AntiVir program, Dupehunter only takes 9.5 minutes.
| How fast is Dupehunter Professional? |
Speed varies depending on various environments, but on a 2.8 GHz Pentium 4 with activated hyper-threading we successfully tested a speed of 165 gigabytes per hour.
The speed for some big files is much better than for thousands of small files. A scan of one million very small files (each size < 100 bytes) was ready within 10 minutes.
| Did you scan huge volumes > 200 GB? |
Sure! We tested Dupehunter Professional with huge data volumes up to 1.8 terabytes (1800 gigabytes) within 11 hours at a speed of 165 gigabytes per hour. But bigger volumes than 1.8 terabyte are also possible.
| Is there any problem on multi-processor machines? |
Multi-processor machines are business computers. These are computers with two or more processors. This means two physical processors and not the hyper-threading technology from Intel. Hyper-threading simulates a second processor by its chipset. Both can be combined. We use a dual-Xeon-Server with 2 x 2 GHz Xeon processors and these CPUs also support hyper-threading (HT). Here Windows XP recognizes four processors and not only the two physical processors.
Dupehunter Professional no longer has problems with hyper-threading and multi-processor machines!
| Does the program support a byte-for-byte scan? |
Yes.
| How secure is Dupehunter professional? |
Absolutely secure. Because, since version 4.0, Dupehunter uses three different algorithms with an additional file size comparison. In newer versions an additional byte-to-byte comparison is done as well.
The recognition is always based on a mathematical calculation of the files and not on other unsecure methods. The algorithms MD5 and SHA1 are the highest level of the technique and are also used by state authorities, police offices and secret services. The additional byte-to-byte comparison runs after calculation of hash values to guarantee 100 percent security. In the newer versions a pure byte-to-byte comparison is available, too.
| Does Dupehunter find zero byte files? |
No!
1. Some programs need files with 0 bytes of file size.
2. A file doesn't have any contents, doesn't have the same content.
3. These files only have negative consequences on older file systems. Such files take up a minimum of one cluster on FAT file systems. All users should change to the better file system NTFS. Here the intelligent routines make sure that these files don't take up any cluster space but are filed directly in the Master File Table (MFT). Therefore the space profit is zero when deleting zero bytes of files at once.
| Which file is the original; which is the copy? |
No idea!
Dupehunter has high secure methods for the recognition of double files. False-positives are impossible with the algorithms MD5 and SHA1 and byte-to-byte comparisons!
However, Dupehunter cannot query in any Windows system for data which would allow saying which file was created first and which was copied. Dupehunter would have to constantly run in the background in order to log all file transactions and collect these data. It gets even more complicated with networks or data carriers that are inserted, if not even impossible!
This is why the ultimate responsibility is left to the user, who decides which files are deleted and which are kept. Dupehunter Professional cannot know which program is used by which file. No duplicate finder in the world can do this.
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