General :: Backup Script Causing Data To Be Lost On Main Server- RHEL?

i setup the following script ro run each night (12am) as a cron on the main server:

if mount | grep -q '/home';
then
rsync -ranv --delete /home/ 138.73.56.12:/home;

[code]....

the main server is running on a dell poweredge 2600. The script rsyncs to a virtualised duplicate running on a hp dl380. when i set this script up and begn running data started going missing from the main server. if new files had been created the files by staff they would go missing, if data was added to existing files prior to activating the script the new changes made to that file would be lost.i just cant understand why this happened. as soon as i turned the script off after a few days it was all back to normal but the data that had gone missing had gone missing.

i just wanted to know if this could be a disk read/write issue, was the script running too soon not allowing data to be written before it can be backed up? could it bee memory? i just dont know. another developed occured after a few days of all this happening, which was one of our hard disk from the main server started mis behaving and flashing amber (attention).