Frequently Asked Questions

Lasted updated on: 12 April 2002
Back | Home

Question:

Answer:

What is an .SFV file? What can I use .SFV files for?

An .SFV file contains a list of file names and special values called CRC checksums. These checksums can have a value in the range of 0 to around 4 billion (for CRC32 sums). These checksums allow files to be verified. If a file becomes corrupt during transferring, the file's checksum will be different to the checksum contained in the .SFV file. This allows .SFV programs to detect corrupt files.

Here are two scenarios where .SFV files might prove extremely useful:

Scenario 1: I want to transfer 516 files across an FTP server to my one friend. The 516 files are contained in many different folders. I want to make sure that the files have not become corrupt during uploading because I'm going to delete them from my computer after he has received them.

Solution 1: Use Easy SFV Creator's "create tree" feature to create an .SFV file for the 516 files that are going to be transferred. After all 516 files and the .SFV file have been uploaded to the FTP server, tell your friend to download an SFV verifying program (preferably Easy SFV Creator) and tell him to open the SFV file so that the files can be checked. After all the files have been checked by the SFV verifying program, he can then tell you if there are any missing or corrupt files. If there are missing or corrupt files, he can tell you which file(s) you need to re-upload. If all the files have been transferred correctly, you can safely delete them from your system.

Scenario 2: My one friend has a CD-ROM image on his hard-drive. The .ISO file is around 600 MB and he doesn't mind putting it up on his FTP server for me to download. I'm on dial-up and from experience, I know that I'll never be able to get a 600 MB file during a single dial-up session. What can I do?

Solution 2: Ask the friend to use Easy SFV Creator's "split" feature to break the .ISO file into smaller pieces. Easy SFV Creator will split the .ISO file apart and also create an .SFV file to make sure that no files have become corrupt during the downloads. Easy SFV Creator's "combine" feature can then be used to combine and check the smaller split files that were downloaded.

How do I extract the .SFV file I downloaded?

Use Easy SFV Creator's "combine" feature. If you attempt to combine an .SFV file that was not created by Easy SFV Creator, the following dialog will be displayed:

If you see this dialog, you should rather stop the combine process and use one of the programs mentioned below. To find the required program, look at the file extensions of the files that you have received. If you see any of the following file extensions, use the associated program to open it:

.ZIP - WinZip
.RAR - WinRAR
.ACE - WinAce
.000 - WinRAR
.001 - WinRAR

If you can't find any of the preceding file extensions and the .SFV wasn't created with Easy SFV Creator's split feature, you can e-mail me the .SFV file that you received. I'm sure I could tell you what program you require (if you even need a program to extract anything).

I downloaded Easy SFV Creator, but when I run the setup, another program's setup is displayed. What must I do?

This is a small bug in WinZip Self-Extractor. WinZip Self-Extractor is the program I use to distribute my installation programs with. The bug occurs very rarely. It has only happened to me once and I've run hundreds of WinZip Self-Extractor self extracting archives.

To overcome the problem, clean out all the files and folders from your system's Temporary folder and run the setup program again. Another workaround is to manually extract the contents of the package you downloaded. You can, for example, open (esfvc???.exe) with WinZip and extract the setup to a folder. Open that folder in Explorer and run SETUP.EXE.

If your questions are not answered, you can e-mail them to me and I'll attempt to answer them.

Total of hits since 26 July 2001.

Brad Smith
bssite@hotmail.com