“文件备份”常见的英文表达是 "file backup" 。
例如：
It's important to regularly perform a file backup to prevent data loss.（定期进行文件备份以防止数据丢失是很重要的。）
Don't forget to make a file backup before you format the hard drive.（格式化硬盘前别忘了做文件备份 。）