i backup my file on a remote disk available on network and mounted with smbfs, therefore it has a limit size of 2GB. so in webmin i set "tape size" to 1GB and check "Split across multiple files?" but webmin filesystem backup doesn't create file01 file02 etc but create one file and when it reach 1GB size it overwrites it! is it a problem of webmin or a limit of tar splitting on remote filesystem?
Are you backing up to a remote system via SSH or FTP, or to a locally mounted smbfs filesystem?