wmp@wperkins.UUCP (William M. Perkins) (10/08/90)
While I was digging around in my new batch of Fred Fish disks, I found some interesting C sources on Fred Fish # 365 for a set of backup and restore archive programs written by Oliver Enselling. The process the software uses is simular to the KwikBackup code that was distributed about two years ago as shareware by Tigress Software. The data is written in a stream format, one disk sector after another. This format is not readable as a regular AmigaDos disk. The process is real fast doing either backups or restores! The code on the Fred Fish disk was C source only, no binaries. No problem! I ran the sources through my SAS 5.10 C compiler with only a couple of snags and proceeded to test the code. The backup was much quicker than a couple of other programs I had tested, like MRBackup. Okey I said, let us see how quick to restore. Restore was fast! I had backed up one of my directories to three floppies and restored them to a different partition. I was satified with the speed and unhappy with the non-standard disk format. Well, you cannot have everything! I decided to do some file comparisons because of some problems I had had with other backup programs. So I started to check the accuracy of the restored files. What I discovered was one BIG problem which currently makes the software unusable. The backup program uses every sector on the disk, which is okey, but a file will most likely overlap from one disk to the next. This overlapping file gets one byte changed to a NULL when it is backed up. Every file that overlapped between disks received this NULL byte. I found out by checking the backup disks with DiskX, a disk editor program by Steve Tibbett, that the same sector on each disk had the same byte set to NULL. The position of the NULL byte on the disk correlated with the NULL byte error on each of the overlapping files. For your information, the location of the errors as given by DiskX was always byte 8 of sector 1749 on the backup disks. I corrected the backup disk byte errors and restored the disks again. All of the files restored correctly. So, there is some kind of a problem with the backup.c source code. The restore.c code works okey. I am working on the problem because I want a quick and *cheap* backup-to-floppy program until I get my scsi tape backup code working on my Hardframe. (I also need a usable scsi tape drive. :-) I could not find an address of any kind for Oliver Enseling, the author of the software, in the documentation or source code. I let you know if I find the bug in the source. I cannot figure out _WHY_ the error is always byte 8 of sector 1749! That is near the end of the disk but not at the end of the disk! *sigh* Happy coding everyone! Bill --- William M. Perkins Of course we run UUCP on an Amiga! The Greenwood wmp@wperkins.UUCP +1 703 590 0207 uunet!pyrdc!wperkins!wmp