There are two basic ways to create a copy of a file.
The first relatively simple method is called a periodic dump (or a full-volume dump, a periodic fallback). This approach is to transfer the contents of all the files in the memory to a certain medium, usually a tape or a disk, at a fixed time period.
Advantages:
The file system can re-assemble the files, placing all the blocks of the user scattered throughout the disk in a contiguous manner. This way, when you start the system again, access to the user's files is much faster.
Disadvantages:
1. The file system may be forced to stop working during the entire dump.
2, the dump generally takes a relatively long time, it depends on the size of the system and the speed of the tape drive.
The other is an incremental dump, a technique that dumps only information that has changed since the last dump, that is, only those files that were subsequently created or changed will be dumped.
Advantages:
1. The file system can re-assemble the files.
2, can meet the requirements of rapid recovery and recovery to the state of the failure of the system.
3, can be carried out in a shorter period of time.
Disadvantages:
The updated file must be marked and eliminated after the dump.
What is a full-scale dump, what is an incremental dump, and what are the advantages and disadvantages?