Thus, this small utility has helped me to avoid possible losses of my data. Only, he had one restriction: can't process subfolders. To process a tree of folders I move in subfolder, launch the md5sum, move in the following subfolder, etc… It was rather tiresome and took away from me a heap of time.

I have decided that this process should be automated. Of course, to make recursive detour of subdirectories in language of scripts in Unix, this utility whence has come, it would be simple enough. Moreover, the version of the utility under Unix already had a feature for work with subdirectories. However, I needed such means under Windows and I still wanted to make some additions for the even greater automation and convenience of use.

In result I have written the program and called it Advanced CheckSum Verifier (in further ACSV). The program has two modes of operation: updating and verifying. In the updating mode it create special files with the checksums of files in the specified folder. In the verifying mode the program read these files and compares these values to the current checksum values of files. And if it finds out discrepancy (or absence of any file) the error event will be logged.

Now I launch the program, it start to scan the specified folders tree, and I quietly am engaged in the affairs. After completion of scanning, I look through the processing log. If I find files which has been damaged, I leave them for the next session of recording to CD - R. And speed of work of the program high enough: on my PII-400 under Windows NT 4.0 with 50-speed ASUS CD-ROM, the checking of the whole compact disc occupies about 2-3 minutes. Earlier when I used the program md5sum, it took away from me almost half an hour (if there were many folders).