John from Pigeon, MI asks,
When you backup, how can you update what is new, and not take up a lot of space with duplicates?
When you run a backup, the first time you backup, you always want to do a full backup. This will backup all the files and folders on your hard drive. This should be done on a fairly regular basis. The disadvantages of full backups are that may take a long time and also could take up a lot of disk space. But it is easy to restore from that backup, if needed, as all files are in one location. However, to avoid using all that space, there are options other than a full backup available in most backup software.
One option is an incremental backup. This means that, after the full backup, the backup will only look for the files that have changed since the last incremental backup. So, say you did a full backup on Monday. Then, you do an incremental backup on Tuesday. That backup will look for any files that have changed since Monday. If you then run an incremental backup on Thursday, it will look for any files that have changed since Tuesday.
The advantages of this method are the backups are quicker and take up less disk space. You also could have several versions of the same files in different backup sets. However, the disadvantages come when it comes to restoring the files. This will take longer, because you must search each incremental backup to find the most recent version of each file.
Another option is called a differential backup. Differential backups also look at changes from the full backup. But in this case, it usually only changes the files changed from the last full backup, but sometimes software varies in this area. A typical differential backup looks like this. You perform a full backup on Monday. Then when you perform a differential backup on Tuesday, it will change all the files that have changed since the full backup on Monday. On Thursday, a differential backup will look for all the files that have changed since Monday’s full backup.
The advantages of differential backups are that they take less space than incremental backups and are generally faster than incremental backups. However, restoring requires that you restore both the last differential as well as the full backup, so it will take longer. It also may take longer to find an individual file because you’ll have to look through both the full backup and the differential backup.