Backing up audit data with growisofs
CD/DVD burner handling on Linux has always been flaky, without much developer or vendor interest in fixing the problems. DVD+R's got the worst of it.
If your drive is the type that can un-eject, do an "eject disk" and "eject -t disk" after each writing operation. I never dared user growisofs to grow an ISO filesystem, just to write to DVD+Rs when dvdrecord/cdrecord stopped working on DVD+R. Both with growisofs and cdrecord, I usually had to eject / uneject to get a freshly written disk to work.